Search

To alleviate the energy crisis and achieve green energy conversion, the heterojunctions that can be applied to the photocatalytic decomposition of water have attracted attention. In this paper, we design a novel two-dimensional GeC/SnSe 2 heterostructure and investigate in detail the structural stability, electronic characteristics, photocatalytic activity and optical behavior as well as the effects due to the applied strain based on the first-principles. Firstly, the most stable γ-stacking mode is determined by combining energy comparison, thermodynamic and dynamic studies. Second, the analysis of electronic properties demonstrates that the GeC/SnSe 2 heterostructure exhibits a type-II energy band arrangement and a direct Z-scheme photocatalytic mechanism. This pivotal aspect enhances the separation of photogenerated carriers at the interface and facilitates the active participation of the most proficient materials in oxidation-reduction processes during photocatalytic hydrolysis reactions. The hydrolysis reaction's Gibbs free energy shift demonstrates the GeC/SnSe 2 heterostructure's superior photocatalytic activity in neutral and alkaline environments and can spontaneously carry out the overall hydrolysis reaction, and this outstanding ability is not affected by the −4% to 4% strain range. In addition, the GeC/SnSe 2 heterostructure has outstanding solar-to-hydrogen efficiency (58.18%) and excellent light absorption capability (up to 4 × 1 0 5 cm − 1 ) within visible light. The implications of these discoveries point towards the direct Z-scheme GeC/SnSe 2 heterostructure holds promise as an excellent candidate for photocatalytic water splitting applications. Free energy descriptions of the GeC/SnSe 2 heterostructure participating in water splitting (a) hydrogen evolution reaction and (b) oxygen evolution reaction under different conditions. Top and side views of the most stable adsorption sites for (c) H on the GeC layer and (d) OH, (e) O and (f) OOH on the SnSe 2 layer of the GeC/SnSe 2 heterostructure. The H and O atoms are represented by pink and red balls, respectively. [Display omitted] • The GeC/SnSe 2 heterostructure is thermodynamic, dynamic and thermal stable. • The GeC/SnSe 2 heterostructure exhibits direct Z-scheme mechanism and strong redox capacity. • Gibbs free energy diagram of water splitting demonstrates its excellent spontaneous reaction capability. • The GeC/SnSe 2 heterostructure has excellent light absorption capability within visible light. [ABSTRACT FROM AUTHOR]

Modern energy systems are large distributed systems and, as a rule, contain energy storage systems and, in particular, hydrogen batteries and hydrogen production systems. The use of hydrogen for energy transportation has recently been actively studied in a number of scientific projects. To ensure continuous operation of instrumentation and control equipment on long hydrogen pipelines (gas and cryogenic), it is important to ensure constant autonomous power supply to these systems. This can be solved using micromechanical energy microgeneration systems for the uninterrupted operation of various sensors, which are installed in large numbers on almost all elements of the structure and infrastructure. In addition, an important area of scientific research is the revision of the concepts and appearance of traditional devices of modern renewable energy: windmills, solar cells, turbines, etc. Fundamentally new energy devices are on the agenda, capable of recovering mechanical energy of any power and supplying it to the consumer in the form of a given specific energy flow. Collection of chaotically distributed natural energy of the environment (mechanical energy in the form of: vibrations, acoustic vibrations, wave energy, gusts of wind, tornadoes, precipitation, vibrations of the earth's crust, etc.), as well as collection of dissipated energy from artificial sources (iron and automobile highways, airstrips, spaceports, production facilities, etc.) with the help of mechanical microgenerators will allow the recovery and conversion of mechanical energy of various powers, including low power, into a universal energy carrier - hydrogen. Mechanical vibrations of artificial origin are of particular interest due to their widespread use for domestic and industrial purposes in a wide range of vibrations. The energy of mechanical vibrations can be collected and converted into electrical energy using piezoelectric, electromagnetic, triboelectric or electrostatic (capacitive) energy converters. Electrostatic microelectromechanical energy converters are considered the most promising among other energy converters, since their manufacturing processes are based on standard technology for the production of integrated circuits and microelectromechanical systems. Energy conversion by an electrostatic converter is carried out due to an external mechanical force that does work against the force of attraction of the charged electrodes of a variable capacitor. To transfer the received electrical energy to the load of the consuming device, the electrostatic converter is connected to the corresponding electrical circuits (conditioning circuits). Such a system as a whole is a kind of microgenerator or energy collector. Microenergy flow recovery systems integrated into large energy systems will ensure the collection and recovery of significant amounts of energy for remote energy consumers. At the same time, the concept of a distributed mechanical energy recovery system is quite simple: a mechanical energy receiver - a converter into electrical energy - a preliminary electrical storage device - an energy distributor - an electric energy accumulator - an electrolyser - a hydrogen accumulator - a fuel cell. To optimize the operation of the working circuit, including preliminary electrical systems for energy storage and conversion: capacitors and electric energy accumulators, electrolyzers; To ensure their durability and reliability, flexible automatic control of electrical power distribution is necessary. The real work was done to solve that problem. In addition, for extended and large power facilities it is important to ensure widespread sensory control of system parameters. At the same time, if all sensors receive power from an autonomous energy-generating device, then the costs of creating extended communications for instrumentation will be sharply reduced. In addition, the reliability of the control system will significantly increase. The results of studying operation features of a kinetic microgenerator with reduced output voltage are presented. The performance of a multi-stage modified Bennet doubler is compared to a system including a two-stage modified Bennet doubler and a diode-capacitor voltage divider. It is shown that with an increase of the number of stages in the modified Bennet doubler, the conversion of mechanical energy into electrical energy becomes less and less efficient. At the same time, for achieving the maximum energy accumulation rate (power), a two-stage power amplifier based on the Bennet doubler is preferable. It is established that when analyzing the operation of a diode-capacitor voltage divider, it is necessary to take into account the intrinsic (reverse) capacitances of the discharging diodes affecting the divider operation significantly. The divider behavior features while changing the load resistance and the intrinsic capacitances of the discharge diodes are found and analyzed. Analytical expressions linking the main characteristics of the microgenerator as a whole with the parameters of the electronic components used are derived. It is shown that for expanding the range of the "correct" division of the divider, it is necessary to use discharge diodes with minimal intrinsic capacitances, and also that connecting a load to the Bennet doubler as a voltage divider changes the permissible capacitance modulation depth of the variable capacitor. This paper examines the concepts of creating large energy-generating flows based on arrays of micromechanical energy converters placed on optimal energy-efficient receiving surfaces and analyzes the issues of cryogenic production, storage, consumption and transportation of hydrogen. Stationary and mobile cryogenic storage systems for hydrogen are considered. Much attention is paid to the safety of large cryogenic and gas hydrogen systems. [ABSTRACT FROM AUTHOR]

Hydrogen is a clean energy in the world and by-product hydrogen is an important part of global hydrogen production. The yield of by-product hydrogen accounts for 18% of hydrogen production globally. To analyze the current stage and calculate CO 2 emissions reduction of by-product hydrogen, sources, purification technology, utilization models, comparison of by-product hydrogen and other hydrogen resources, reduction of CO 2 emissions, prospects of industrial by-product hydrogen were analyzed from the respective of industrial utilization. The resources of by-product hydrogen will get expanded further. It can facilitate the utilization of industrial by-product hydrogen to establish industrial zone with the factories producing by-product hydrogen and the downstream factories utilizing by-product hydrogen under the current technology conditions. By analyzing the relevant data, it is calculated that the utilization of industrial by-product hydrogen can reduce CO 2 emissions by 6.11x105 t per year in 2022. With the development of hydrogen purification technology, by-product hydrogen can provide an efficient and economical way to reduce CO 2 emissions for global warming migration before the completion of green hydrogen substitution for other hydrogen. [Display omitted] • CO 2 emissions reduction can reach 6.11x105 t/a through the utilization of by-product hydrogen in 2022. • Hydrogen purification technology plays a significant role in the utilization of industrial by-product hydrogen. • The resources of industrial by-product hydrogen will get expanded in the future. [ABSTRACT FROM AUTHOR]

Liquid oxygen/methane engines have high ignition energy and long ignition delay time. To improve its ignition and combustion performance, this research proposes an online methane reforming technology using dielectric barrier discharge. The performance of methane reforming by single/double layer dielectric barrier discharge plasma with high-frequency AC and nanosecond pulse excitation was comprehensively evaluated and compared through experiments and simulation. To evaluate the feasibility of this technology, numerical simulations were introduced to investigate the potential improvement of reformed methane on rocket engine performance. The results show that compared to high-frequency AC excitation, nanosecond pulse excitation dissipates less discharge energy, resulting in a methane conversion rate of 4%, H 2 selectivity of 13%, and C 2 H 4 selectivity of 6% higher than high-frequency AC excitation. Increasing the excitation voltage and frequency could promote methane cracking from 1.9% to 8% while the energy conversion efficiency decreases from a maximum of 6%–3.8%, and the carbon balance index also decreases from a maximum of 99.7%–97.25%. Double layer dielectric barrier discharge is more uniform than single layer dielectric barrier discharge structure, which can reduce the accumulation of by-products and have higher selectivity for H 2. The nanosecond pulse double layer dielectric barrier discharge plasma technology has ideal methane reforming performance and high energy efficiency, making it suitable for online methane reforming. In addition, methane reforming could improve rocket engine combustion performance by accelerating flame development and expanding the high-temperature area, leading to the engine specific impulse increasing by 3.9%. • DBD plasma methane reforming has rocket engine combustion supporting feasibility. • Excitation parameters optimization can improve methane conversion rate. • The engine specific impulse can be increased by DBD plasma reforming. • Bilayer structure leads to by-products reduction and higher H 2 selectivity. [ABSTRACT FROM AUTHOR]

Clean energy devices have a great ability to change the world because they strengthen the economy and preserve society. The continuous improvement and progress in nanomaterials and nanotechnology have a great role in human life. The increasing prevalence of PEM fuel cells makes them one of the most viable sustainable energy sources. Nanostructured materials synthesis methodologies have introduced a breakthrough and found to overcome the obstacles for PEMFC commercialization. Amongst them, wet chemical approaches are rapidly expanding and beneficial for the fabrication of nanoparticles since they contribute toward the attainment of a range of essential nanoparticle characteristics like sizes, morphologies, structures, and phases. Wet chemical manufacturing enables fine-tuning of reaction parameters to generate the desired nanomaterials. This review article focuses on the latest improvements in wet chemical methods to better regulate the quality of nanomaterials. This paper examines how wet chemical approaches (hydrothermal synthesis, spray pyrolysis, sol-gel processing, and co-precipitate synthesis, among others) can contribute to the scalable manufacturing of nanoparticles to uphold rising industrial requirements. And how wet chemical methods have a significant influence on power generation systems (Fuel cells) along with their pros and cons. This review carefully analyzes and summarizes synthetic methods and optimized factors in order to prepare nanoparticles and carefully analyzes the reported data. In this paper, the electrochemical analysis, morphological evaluation, compositional analysis, and performance testing of materials produced using wet chemical techniques have been investigated. Recent signs of progress and innovative techniques used to overcome the complexities of synthetic nanoparticle processing. This article is a holistic approach including social, economic, and ecological aspects in the wet chemical process and will certainly help in the fabrication, and application of nanoparticles for PEM Fuel cells. [Display omitted] • Introduction to the status of materials synthesis in energy generating devices. • Overview of wet chemistry Approaches for PEMFC. • Impact of synthesis parameters on properties of materials. • Pros and Cons of wet chemistry techniques for material synthesis. [ABSTRACT FROM AUTHOR]

Rare earth-based perovskite nanostructures are potential materials for electrocatalytic water splitting and energy storage applications due to their great chemical stability. DyMnO 3 nanoaggregates and DyFeO 3 nanoflakes were synthesized using the polymeric citrate precursor and ethylene glycol-assisted hydrothermal routes, respectively. A comprehensive set of characterization techniques, including X-ray diffraction, scanning and transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and Brunauer–Emmett–Teller (BET) surface area analysis were carried out. Surface area studies showed that DyMnO 3 has higher specific surface area (33 m2/g) than DyFeO 3 nanoflakes (8 m2/g). Electrochemical water splitting and supercapacitor performance revealed DyMnO 3 nanoaggregates displayed remarkable activity for oxygen evolution reaction with an overpotential of 0.22 V vs. RHE and a faster reaction kinetics. DyFeO 3 nanoflakes demonstrated superior pseudo-capacitance behavior, exhibiting a specific capacitance of 97.82 F/g and 100 % coulombic efficiency. These findings contribute to the advancement of materials design for electrochemical energy conversion and storage applications, emphasizing the potential of rare earth-based perovskite nanostructures in sustainable energy technologies. [Display omitted] • Citrate and hydrothermal techniques employed for diverse synthesis approaches. • Studied multiferroic nature; DyMnO 3 NAs exhibits enhanced characteristics-unit e g filling, high specific surface area. • DyMnO 3 NAs showed superior OER performance (0.22 V vs. RHE) in overall electrocatalytic water splitting. • DyFeO 3 NWs showed superior supercapacitor performance of specific capacitance of 97.82 F/g. [ABSTRACT FROM AUTHOR]

Biohydrogen production is influenced by various parameters such as production formation rate, substrates degradation, and biomass utilization. Therefore, it is crucial to predict the kinetics of proper yield. This study was designed to perform a comprehensive kinetic analysis based on several linear or non-linear models. The experimental data analyzed was different co-culture ratios of microalgae and activated sludge with hexitols (glucose, sorbitol, mannitol) as carbon substrates. Results suggest that modified Gompertz model best predicts biohydrogen potential and acetate production in different co-cultures with high R2 values (>0.977 and > 0.982), respectively. A maximum of 9.8 % energy conversion efficiency is achieved in 10 g/L glucose supplemented co-culture, equivalent to traditional fuels. The linearized Luedeking–Piret model also indicates that biohydrogen production is influenced more by substrate degradation/utilization than microalgal biomass. These tools can be utilized to optimize the operational parameters and access the best fit of experimental data for enhanced yield. [Display omitted] • Excellent data fittings of parameters involved in algal activated sludge co-culture. • Biohydrogen and acetate yield can be best predicted by Modified Gompertz model. • Michaelis–Menten model best described kinetic of substrate degradation/utilization. • Relationship of products, substrate, and biomass predicted by Luedeking–Piret model. • Maximum energy conversion efficiency (9.8 %) was achieved in 1:1.5 co-culture ratio. [ABSTRACT FROM AUTHOR]

The development of active, stable, earth-abundant, and cheap catalysts is crucial for renewable energy conversion devices. Catalysts for electrochemical water splitting are prepared using cold uniaxial pressing and consist of a superficial ferrite coating on a nickel substrate. The activity and mechanism of the oxygen (OER) and hydrogen (HER) evolution reactions on powder compacts are investigated. It is found that powder compacts are efficient catalysts for oxygen and hydrogen evolution in a 1 M KOH solution. For Ni/NiFe 2 O 4 , the current density of 10 mAcm−2 in OER and −10 mAcm−2 in HER shows overpotentials of 272 mV and −43 mV, respectively. In turn, for Ni/CoFe 2 O 4 , those overpotentials are 279 mV and −37 mV. Furthermore, using the same material for the anode and cathode in a two-electrode cell configuration, one can achieve a 10 mAcm−2 water splitting current at only 1.55 V for over 48 h without coating degradation. It is stated that the high activity towards OER and HER results from the large electrochemically active surface area and high electrical conductivity of powder compacts. The results also indicate that the most probable rate-determining steps for OER and HER are the formation of the adsorbed oxide atom and H 2 molecule, respectively. [Display omitted] • Pressed nickel and cobalt ferrite powder compacts are prepared. • Kinetics of OER and HER on ferrite electrodes are discussed. • Mechanisms of OER and HER on ferrite electrodes are discussed. • Ferrite electrodes achieve comparable activity to noble metal electrocatalysts. [ABSTRACT FROM AUTHOR]

Electrochemical capacitors and hydrogen production through water splitting into constituent hydrogen (H 2) and oxygen (O 2) molecules are promising methods for long-lasting energy storage. This work presents a simple synthesis of a cobalt ion-doped vanadium carbide MXene (Co@V 2 CT x) nanocomposite, utilized as an effective, durable, and stable electrode for supercapacitors and as an electrocatalyst for water electrolysis. In 1 M KOH, the Co@V 2 CT x nanocomposite produced a capacitance of 1071 Fg-1 at 5 mVs−1 (more than 8 times that of pristine V 2 CT x MXene) and an energy and power density of 26.7 Whkg−1 and 325 Wkg-1 respectively at 1 Ag-1. In addition, the Co@V 2 CT x nanocomposite showed good hydrogen evolution reaction (HER) catalytic activity, exhibiting a minimal overpotential of 103 mV at 10 mAcm−2 and Tafel slope of 83 mVdec−1. The excellent performance of the Co@V 2 CT x nanocomposite is due to the synergistic effects produced when cobalt ions are intercalated into the vanadium carbide MXene, preventing restacking of sheets and boosting ion transfer. This work presents an easy and effective method for synthesizing MXene-based nanocomposites for energy storage and conversion applications. • Co@V 2 CT x electrodes were prepared through simple co-precipitation method. • The anchored Co-intercalated V 2 CT x sheets, prevent restacking and increase surface area. • The Co@V 2 CT x material showed excellent supercapacitive and electrocatalyst for water-splitting. • The proposed material provide adequate conductive pathways for ion movement. [ABSTRACT FROM AUTHOR]

The construction of heterogeneous interface significantly contributes to the boosted electrocatalytic activity for hydrogen evolution reaction (HER). This enhancement is achieved through the modulation of the electronic structure, facilitation of electron redistribution, and optimization of the electrocatalyst's chemisorption towards the reaction intermediates. Herein, NiS 2 /Co 3 S 4 heterojunction was synthesized using a straightforward one-pot hydrothermal method, and the impact of heterogeneous interface on the electrocatalytic HER performances was investigated. The heterogeneous interface and strengthened interfacial effects between NiS 2 and Co 3 S 4 were confirmed by HRTEM and XPS. The NiS 2 /Co 3 S 4 heterojunction demonstrate significantly enhanced HER performance in acidic solutions, owing to their clever structural design and the robust interfacial coupling effects within the heterogeneous interface structure, surpassing that of single-component NiS 2 materials. The optimum NiS 2 /Co 3 S 4 heterojunction presents a low overpotential of 253 mV and a Tafel slope of 62.0 mV dec−1 at 10 mA cm−2 toward HER. Density functional theory (DFT) calculation indicates that NiS 2 /Co 3 S 4 heterostructure exhibit lower ΔG H* values compared to NiS 2 and Co 3 S 4. This suggests that the creation of heterogeneous interface can significantly optimize the adsorption capacity for hydrogen intermediates, thereby enhancing the HER in acidic media. • NiS 2 /Co 3 S 4 heterojunction were synthesized using a straightforward one-pot hydrothermal method. • The optimum NiS 2 /Co 3 S 4 heterojunction presents superior hydrogen evolution reaction than that of their counterparts NiS 2. • Density functional theory reveals a lowered ΔG H* of heterogenous interfaces to boost HER. [ABSTRACT FROM AUTHOR]

Solid Oxide Fuel Cell (SOFC) stacks are one of the most critical modules in industrial SOFC energy conversion systems. Although the detailed multiphysics distribution has been elaborately studied with accurate 3-dimensional (3D) models, development and validation of agile stack model is yet inadequate. Due to slow and tedious meshing and simulation, fast prototyping of stacks remains a challenge. Therefore, a 30-cell stack was tested at varied temperatures and gas flowrates and a real-time transient layer-resolved stack model is established and calibrated using the measured data, which gives a Root-Mean-Square (RMS) prediction error of 2.21% for measured voltages and 1.53 °C for measured temperatures. With layer resolution, the stack model shows the voltage, average temperature, as well as fuel and air flowrates of each cell. Moreover, the stack model reveals the relation of voltage distribution at varied fuel flowrates with temperature distribution. Furthermore, the stack model is potentially applicable to stack scaling effects, or designing Balance of Plant (BoP). [Display omitted] • An accurate layer-resolved stack model for voltage/temperature distributions. • Low computational cost of the model enabling agile and real-time applications. • Explained the role of operating conditions on flowrate inhomogeneity. • Revealed strong impact of temperature on stack voltage distribution. [ABSTRACT FROM AUTHOR]

We report the structure analysis and electrocatalytic application toward overall water splitting of atomically precise Au 15 Ag 23 ( t BuC ≡ C) 18 Br 6 nanoclusters (Au 15 Ag 23 in short). Au 15 Ag 23 possesses a triple-layered core-shell-shell metal core structure of Au 6 @Au 6 Ag 23 @Au 3 , with the core centre being a tetragonal bipyramidal Au 6 structure unit, and the outer layer of one Ag atom linked with two alkynyl ligands to form a linear structural motif covering the surface of the metal nucleus. Au 15 Ag 23 is a superatom with 14 free electrons and it displays a unique absorption profile. Remarkably, the Au 15 Ag 23 catalyst exhibits excellent electrocatalytic properties in hydrogen evolution reaction (HER), manifested by a low overpotential of 125 mV at 10 mA cm−2 and a negligible current decrease for 16 h in 0.5 M H 2 SO 4 , while the Au 15 Ag 23 /NiFe-LDH catalyst demonstrates outstanding electrocatalytic performance in oxygen evolution reaction (OER), evidenced by an ultralow overpotential of 250 mV at 10 mA cm−2 and a ∼5% current decrease for 30 h in 1.0 M KOH. Such promoting effect is ascribed by the electron transfer from NiFe-LDH to the Au 15 Ag 23 clusters, which results in generating high valent Fe species as active sites. When using the two catalysts for overall water splitting (OWS), only 1.51 V was required to achieve a current density of 10 mA cm−2, and it performed well in the 50 h's stability test. This study enriches the family member of alkynyl-protected AuAg bimetallic nanoclusters, and further highlights the dual functionalities (catalyzing HER and promoting OER) that metal nanoclusters can make contribution for electrochemical energy conversion and beyond. [Display omitted] • A novel atomically precise Au 15 Ag 23 ( t BuC ≡ C) 18 Br 6 nanocluster is reported. • Au 15 Ag 23 cluster possess intriguing HER catalytic properties. • Au 15 Ag 23 cluster can significantly promote the OER performance of NiFe-LDH. • The electron transfer from NiFe-LDH to Au 15 Ag 23 cluster boosted the OER performance. [ABSTRACT FROM AUTHOR]

The high temperature batch and continuous pyrolysis of rice husk, sewage sludge, composite waste, hazelnut and apricot kernel shell were performed at 850 °C in a rotating batch reactor and a continuous reactor with a modified ribbon screw conveyor. Batch results were used in the continuous reactor design and comparison. At the continuous pyrolysis experiments, mixing and conveying efficiency of screw and thermal cracking performance of reactor, heated gas line and cyclone were investigated. Each material was fed into the reactor continuously with a feed rate of 4.5 kg/h for 3.5 h, and then the pipelines and reactor were monitored and collected tar and char were analyzed. The mixing unit and uninterrupted heated system showed excellent performance on tar reduction and tar yields were lower than 1.7 % for all materials. Separation of char dust from the gas without tar condensation in a heated cyclone prevented blocking in gas lines. With the secondary reactions syngas energy conversion efficiency for rice husk, sewage sludge, composite waste, hazelnut shell, and apricot kernel shell were 67.76 %, 59.22 %, 76.35 %, 56.96 %, 61.98 % respectively. With the new design with a modified ribbon screw, different types of materials were decomposed with minimum char yield in less than 15 min without mechanical problems. The high capacity of the installed reactor as 1–10 kg/h moved the technology readiness level (TRL) to 5 and set an example for demonstration in operational environment. [Display omitted] • Continuous reactor with modified screw was designed and operated for five different biomass and waste. • Tar minimization up to 0,4 % and useful conversion efficiency up to 91,5 % was achieved. • Hydrogen and methane enriched clean syngas production was provided. • The high-capacity semi-pilot system of 10 kg/h shed light on demo scale designs. • Novel conveying system was operated without sticking, fouling or blocking. [ABSTRACT FROM AUTHOR]

In order to improve the energy efficiency of the Sabatier reactor-based power-to-gas process, molten carbonate fuel cells and solid oxide electrolyzers were installed instead of a conventional amine CO 2 capture system and a classical alkaline electrolyzer. The plant is a multi-module prototype with a nominal capacity of 50 kW consisting of two SOE-MCFC units. The system was commissioned in 2022. The article describes the theoretical basis. The initial assumptions that were formulated at the stage of preparing for the research investment, as well as the deviations from them that became the result of detailed design were presented. The developed startup and shutdown procedures, as well as the first results of pioneering research were shown. The trial operation of the system was intended to provide information on integrated SOE-MCFC module and its performance and efficiency. The basic barriers for market implementation and recommendations for future research were discussed. The optimal operating point for hydrogen production needed 35.8 kWh/kgH 2. Thus, electrical energy conversion to chemical energy efficiency is 93.9%. Flow preheating and electrical auxiliary heater power are not included. An MCFC at its ideal functioning point (around 4 kW el) outputs 5.4 kg/h of CO 2 separated. • Operational experience of upgraded novel P2G installation is reported. • A start-up procedure of MCFC-SOE tandem in proposed and experimentally verified. • Energy required for synthesis of a kilogram of hydrogen was 35.8 kWh/kgH 2. [ABSTRACT FROM AUTHOR]

In this work, the effect of ash particle size on the sequential production of bioH 2 and bioCH 4 for biohythane recovery from the organic fraction of municipal solid waste (OFMSW) was investigated for the first time using micro- and nano-sized biomass fly ash (FA). In the first hydrogenogenic stage, the highest bioH 2 yield of 215 mL/g VS added was noticed in the reactor added with micro-sized FA. On the contrary, in the second methanogenic stage, the maximum bioCH 4 yield of 676 mL/g VS added was witnessed in the reactor fed with acidogenic effluent containing nano-sized FA. In the integrated two-stage process, the addition of FA with nano-sized particles showed superiority over micro-sized FA supplementation and led to an increase of about 582 and 595% in organic matter conversion and energy yield, respectively, compared to the control test, as well as achieving biohythane with an optimal hydrogen content of 15% v/v. • The particle size of FA additive affected the two-stage biohythane production. • The maximum bioH 2 yield in the 1st stage was obtained by adding micro-sized FA. • The highest bioCH 4 yield in the 2nd stage was related to the nano-sized FA addition. • The best performance of the two integrated stages was attained using nano-sized FA. [ABSTRACT FROM AUTHOR]

A microbial fuel cell (MFC) is an eco-friendly device that uses living microorganisms' catalytic activity for energy harvesting. The power output of this device is still far from the targeted one. An improvement to the power can be accessed via the use of biocompatible high surface area anode materials. Metal-organic frameworks (MOFs) have a high surface area, crystalline, and can be prepared in different morphologies. MOF demonstrated excellent performance in various energy conversion/storage devices. For the first time, a standalone carbon fiber brush electrode modified with Zn-MOF is constructed via a simple hydrothermal approach. The prepared electrodes were investigated as the anode of yeast-based MFC. The MFC with Zn-MOF carbon fiber brush exhibited maximum current and power densities of 317 mA/m2 and 73.7 mW/m2, which are twofold those obtained using bare carbon brush anodes. The significant improvement in the MFC performance with modified carbon fiber brush would be related to the role of the Zn-MOF in facilitating the electron transfer between the anode and the yeast cells and thus promoting bio electrocatalytic activity as confirmed from the redox peaks that appeared during the cyclic voltammetry (CV) of the modified electrodes and supported by electrochemical impedance spectroscopy (EIS). • In-situ Zn-MOF/CB was prepared via hydrothermal method in one-step. • Zn-MOF/CB was investigated for the first time in yeast based MFC. • The modified electrode showed twofold higher power output than the unmodified one. [ABSTRACT FROM AUTHOR]

As a new 2D material, MXenes are anticipated to impact future energy storage and conversion technologies significantly. This article reviews recent progress in MXene-based nanomaterials for oxygen evolution reaction (OER). In addition, the method of synthesizing these materials as an OER and essential concepts to motivate future research were highlighted, and obstacles to the sustainable development of this field were presented. A-layer selective etching with aqueous solutions containing fluoride ions is now the preferred method for developing MXenes. Until now, the difficulty in synthesizing a wide variety of MXenes has been attributed to Al high reactivity with fluoride-based aqueous media, which is particularly potent for those produced from MAX-phase precursors of containing Al. • Recent progress in MXene-based nanomaterials for oxygen evolution reaction is assessed. • Method of synthesizing these materials as an OER and essential concepts were highlighted. • Obstacles to the sustainable development of this field were presented. [ABSTRACT FROM AUTHOR]

Multigenerational energy conversion plants are one of the most promising solutions for tackling environmental challenges and making efficient use of energy sources. In this regard, a newly designed multigeneration plant integrated with a methane-based Brayton cycle, a steam Rankine cycle, a supercritical CO 2 -based Brayton cycle, a multi-effect desalination process, a PEM unit, a domestic water heater process, and two thermoelectric generators is integrated, proposed and analyzed. The thermodynamic and environmental assessments of the developed paper are conducted and examined with energy and exergy efficiencies as well as CO 2 emission rate. Similarly, a parametric study is executed and reported, by the way, to define the impact of the various significant factors on the developed plant's efficiency. In the end, the CO 2 emission rate is determined and compared according to different energy conversion plants. In light of the analysis results, the net power, hydrogen, and freshwater production capacities of the reference study are calculated to be 1336 kW, 0.002004 kgs−1, and 0.954 kgs−1, respectively. Additionally, it is found that the developed study's energetic and exergetic performances are 55.76% and 52.17%. According to emission analysis results, the multigeneration system emits 272.2 k g / M W h less CO 2 emissions than the single energy conversion system. • A newly designed multigeneration plant is suggested. • Combination of a superciritical CO 2 based Brayton cycle is proposed. • Thermodynamic and environmental analysis of the multigeneration plant is conducted. • Freshwater, hydrogen, power and heating purposes are fulfilled. • The overall energy and exergy efficiencies are 55.76% and 52.17%, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a novel energy management strategy (EMS) to control a wind-hydrogen microgrid which includes a wind turbine paired with a hydrogen-based energy storage system (HESS), i.e., hydrogen production, storage and re-electrification facilities, and a local load. This complies with the mini-grid use case as per the IEA-HIA Task 24 Final Report, where three different use cases and configurations of wind farms paired with HESS are proposed in order to promote the integration of wind energy into the grid. Hydrogen production surpluses by wind generation are stored and used to provide a demand-side management solution for energy supply to the local and contractual loads, both in the grid-islanded and connected modes, with corresponding different control objectives. The EMS is based on a hierarchical model predictive control (MPC) in which long-term and short-term operations are addressed. The long-term operations are managed by a high-level MPC, in which power production by wind generation and load demand forecasts are considered in combination with day-ahead market participation. Accordingly, the hydrogen production and re-electrification are scheduled so as to jointly track the load demand, maximize the revenue through electricity market participation and minimize the HESS operating costs. Instead, the management of the short-term operations is entrusted to a low-level MPC, which compensates for any deviations of the actual conditions from the forecasts and refines the power production so as to address the real-time market participation and the short time-scale equipment dynamics and constraints. Both levels also take into account operation requirements and devices' operating ranges through appropriate constraints. The mathematical modeling relies on the mixed-logic dynamic (MLD) framework so that the various logic states and corresponding continuous dynamics of the HESS are considered. This results in a mixed-integer linear program which is solved numerically. The effectiveness of the controller is analyzed by simulations which are carried out using wind forecasts and spot prices of a wind farm in center-south of Italy. • Design of control algorithms for islanded and grid-connected microgrids. • Development of hierarchical MPCs to target long-term and short-term operations. • Tracking the load demand and maximizing the revenue via electricity markets. • Minimization of the HESS operational costs. [ABSTRACT FROM AUTHOR]

The hydrogen compressed natural gas (HCNG) blends play a key role in the European Hydrogen Roadmap targets achievement. The HCNG refuelling stations can be built up by upgrading the existing compressed natural gas stations. This work investigates the thermodynamic of HCNG refuelling processes to determine the impact on gas temperature due to the Joule-Thomson effect, heat transfer through the cylinder wall, the kinetic energy conversion in internal energy, and compression contribution during the fast fill-up. Specifically, the vehicle tank initial conditions and the refuelling parameters have been analysed, evaluating how they affect the final refuelling temperatures, filled mass, relative states of charge, and refuelling times. With an average pressure ramp rate of 0.18 MPa/s, at initial cylinder conditions of 10 °C and 9 MPa, the 0.065 m3 and 0.15 m3 tanks reach a SOC of 93.83% and 65.32% and final temperature of 82.5 °C and 44.5 °C, respectively. • Light duty HCNG vehicle refuelling investigation via thermodynamic analysis. • HCNG blend Joule-Thomson effect on the final refuelling temperature. • Initial cylinder temperatures and pressures impact on the HCNG fast fill up. • Pressure ramp rate impact on final refuelling temperatures and filled mass. • Vehicle tank volume influence on final temperatures and state of charge. [ABSTRACT FROM AUTHOR]

At present, energy shortage and environmental pollution are becoming more and more serious. If environmental governance and energy supply can be combined, it will be more consistent with the long-term concept of sustainable development. Urea electrooxidation may achieve the degradation of pollutants and the conversion of energy supply, urea oxidation occurs at the anode and hydrogen evolution occurs at the cathode. However, the electrochemical oxidation process of urea requires the transfer of six electrons, and the reaction rate is slow. The electrocatalyst is a key factor in improving the reaction kinetics. In this context, catalysts used in urea electrocatalytic oxidation in recent years are reviewed in this paper. The application of the electrocatalyst in electrolytic hydrogen production, urea wastewater treatment, urea fuel cells and urea sensors are described in detail. In addition, the future research directions, research emphases and areas needing improvement of these catalysts are discussed. [Display omitted] • Urea electrooxidation has double benefits of environmental protection and energy supply. • Electrocatalysts for urea electrooxidation in alkaline electrolytes are reviewed. • The applications of electrocatalyst in the electrooxidation of urea are demonstrated. [ABSTRACT FROM AUTHOR]

Constructing efficient and stable photocatalysts are quite crucial for solar-to-hydrogen energy conversion, which remains a great challenge. Nowadays, many photocatalysts still suffer from low solar energy conversion efficiency due to the rapid recombination of photoirradiated carriers mainly caused by their random flow. Regulating charge separation and transport is essential to improve the catalytic activity of photocatalysts toward highly efficient photocatalytic hydrogen production. Herein, a S-scheme In 2 S 3 –ZnIn 2 S 4 /Au heterojunction with coherent interfaces were constructed. Particularly, as a reduction cocatalyst, the plasmonic metallic Au nanoparticles were loading on the outer surface of S-scheme In 2 S 3 –ZnIn 2 S 4 heterojunction. The coordination of S-scheme heterojunction and reductive cocatalyst can produce a directional spatial charge separation and transfer in In 2 S 3 –ZnIn 2 S 4 /Au heterojunction, leading to a highly efficient photocatalytic hydrogen production. As expected, the well-designed S-scheme In 2 S 3 –ZnIn 2 S 4 /Au heterojunction presents a remarkable H 2 production rate of 12,369 μmol h−1 g−1. This charge transfer modulation mechanism may be applied to design other remarkable photocatalytic materials for efficient solar energy conversion. [Display omitted] • In 2 S 3 –ZnIn 2 S 4 /Au can produce a directional spatial charge separation and transfer. • The self-templated fabrication guarantees a chemical interface connection. • In 2 S 3 –ZnIn 2 S 4 /Au presents a remarkable H 2 production rate of 12,369 μmol h−1 g−1. [ABSTRACT FROM AUTHOR]

Rationally designing cost-efficient, high-activity and durable electrocatalysts are used for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is sense to solve the energy crisis and conversion. Herein, the heterostructure superwetting Co–MoS 2 /Ni 3 S 2 -GO/NF electrode is successfully fabricated by a typical hydrothermal reaction and it's electrocatalytic performance is also systematically studied. Thanks to the establishment of Co doped MoS 2 /Ni 3 S 2 heterojunction, the improvement conductivity by the addition of graphene oxide (GO), and the superhydrophilicity and superaerophobicity of microstructure, the electrode shows excellent catalytic characteristics and only need an overpotential of 123 mV for OER and 161 mV for HER to reach 10 mA cm−2 and can work steadily for 15 h in alkaline solution. Remarkebly, the superwetting heterojunction electrode demonstrated excellent overall water decomposition ability when used as bifunctional electrocatalyst in 1.0 M KOH and only 1.47 V is required to achieve 10 mA cm−2. Density functional theory (DFT) calculations show the constructed heterogeneous interface and Co doping are conducive to optimizing the chemisorption energy of hydrogen-containing intermediates. This work provides a new way of thinking that collaborative optimization of electrode structure and surface wettability regulation to increase the active area of reaction and accelerate the bubble release toward high-performance OER and HER electrodes. [Display omitted] • The heterojunction structure Co–MoS 2 /Ni 3 S 2 -GO/NF electrode can be prepared by simple hydrothermal method. • The electrode has superhydrophilicity and underwater superaerophobicity. • The electrode has excellent electrochemical performance and stability. • DFT calculation is used to analyze the efficient catalytic mechanism of the electrode. [ABSTRACT FROM AUTHOR]

This study delves into the exploration of B′ site arranged Cs 2 NaB′Cl 5 perovskites (B′ = Ni, Mn, Fe) as prospective alternatives to lead-based perovskites, given the environmental concerns associated with lead toxicity and material instability. Structural analysis using X-ray diffraction revealed a stable tetragonal crystal structure with the P4/mmm space group. Electronic properties, assessed via density functional theory (DFT) calculations, identified these materials as p-type semiconductors with tunable band gaps, and this finding supported by optical experimental data. Thermogravimetric analysis (TGA) demonstrated decomposition temperatures up to 750 °C, with Cs 2 NaMnCl 5 exhibiting superior thermal stability. Field emission scanning electron microscopy (FESEM) unveiled distinct morphologies influenced by the transition metal in the B′ site, while elemental analysis confirmed material purity. The optical analysis revealed strong light absorption in the visible spectrum, highlighting the potential of these materials for sustainable energy conversion applications. Overall, this research contributes valuable insights into the environmental-friendly potential of B′ site arranged Cs 2 NaB′Cl 5 perovskites in photoelectrochemical and solar cell application. [Display omitted] • Theoretical and experimental studies were carried out for Cs 2 Na B′ Cl 5. • Band structure was stimulated using DFT. • Cs 2 Na B′ Cl 5 (B′ = Ni, Mn, Fe) was synthesized using a simple solution method. • Band gaps of the Cs 2 Na B′ Cl 5 (B′ = Ni, Mn, Fe) were found to be 1.6–2 eV. • Dielectric constants, extinction coefficient, and refractive index are conferred. [ABSTRACT FROM AUTHOR]

Designing highly-efficient, stable and low-cost catalysts for electrocatalytic hydrogen evolution reaction (HER) plays an important role in renewable energy conversion technology. The particularly ultrathin and porous 2D architecture can provide plentiful activation sites, short delivery channels to improve reaction kinetic and promote HER procedure. High-performance transition metal phosphide (CoP) combined with unique and holey 2D ultrathin nanosheet structure is prepared by successively hydrothermal reaction, oxidation and phosphorization techniques, which presents remarkable stability and electrocatalytic HER properties in a wide pH range. The thickness and pore dimension of ultrathin and porous CoP nanosheets are ∼15 and 3–17 nm. The optimized CoP nanosheets only require 60, 128, 90 mV overpotentials to drive the current density of 10 mA cm−2 in acidic, neutral and alkaline environment, respectively, much better than those of oxide counterpart and the previously reported transition metal-based electrocatalysts. Moreover, the small Tafel slopes of porous CoP nanosheets are 54, 69.9 and 62.9 mV dec−1 in acidic, neutral and alkaline media. CoP nanosheets also exhibit high conductivity, large C dl , and long-term stability for 20 h in pH-universal electrolyte. • The unique and neoteric CoP nanosheets were successfully synthesized. • The CoP nanosheets possess ultrathin and porous architecture. • The thickness and pore dimension of ultrathin CoP nanosheets are ∼15 and 3–17 nm. • The optimized CoP nanosheets displayed outstanding HER activity in a wide pH range. [ABSTRACT FROM AUTHOR]

An energy system based on water for creating hydrogen energy might be less globally restricted than one that uses the available fossil fuels today. Therefore, creating an efficient catalyst and electrolyzer system is necessary to effectively convert renewable energy into chemical energy (hydrogen). In this study, a model based on kinetic reaction rate parameters is proposed for estimating energy efficiency and energy conversion for hydrogen generation in a high-voltage alkaline electrolyzer. Three complementary models, including the thermal, electrochemical, and thermodynamic, are conducted to forecast the thermal time constant, overall thermal resistance, operating temperature, electrolyzer voltage, energy consumption, and energy loss. To ensure that they can operate directly with renewable energy sources, the modeling was expanded to incorporate hydrogen production at a voltage level of 6 V. The model's various parameters were computed using non-linear regression presented in Engineering Equation Solver (EES) utilizing experimental data gathered in a high-voltage alkaline test rig. From their precursors and coated on Ti substrates, nanoparticles of Ag, TiO 2 , and Ag + TiO 2 are created as electrocatalysts for the production of hydrogen. In comparison with the bare Ti electrode, the results revealed that energy efficiencies of the Ag, TiO 2 , and Ag + TiO 2 electrodes have increased by 23%, 28%, and 28%, respectively. The largest improvement in hydrogen energy conversion achieved with TiO 2 electrodes over Ti electrodes was 84%. Thermodynamic-thermal models that were integrated showed that the coated electrodes decreased the thermal energy loss (TΔS) and useable energy (ΔG) simultaneously during the electrolysis process. The electrochemical model demonstrated a strong fit to the data from those experiments, indicating that the coated nanomaterials are the most important factor in increasing the electrolyzer energy efficiency-based production of hydrogen. The models presented in this research offered a practical method for increasing hydrogen energy production and energy conversion using nanomaterial to build effective electrolyzer devices. The models described in this study are appropriate for the dynamic simulation of renewable energy-hydrogen systems. As a result, these models are easily connected to economic theories that account for both financial and operation expenses. • A model based on kinetic reaction rates is developed for hydrogen generation in a high-voltage alkaline electrolyzer. • The model demonstrated the efficiency of converting renewable energy into hydrogen. • Hydrogen evolution reaction was primarily limited by the reaction rate constant. • TiO 2 system has the highest energy efficiency (28%) and energy conversion (84%). [ABSTRACT FROM AUTHOR]

Noble metal Rh has been emerged as a potential candidate for energy-related electrocatalytic reactions due to its appropriate adsorption strength with key intermediates and strong resistance in harsh reaction conditions. Although Rh possesses a series of exceptional physiochemical properties, its electrocatalytic performance still can't meet the high requirements for industrial application. To this end, enormous efforts have been devoted to enabling the electrocatalytic performance of Rh to approach to the industrial standard. In this review, we discuss the latest research advances of Rh-based nanostructures for electrocatalytic energy conversion. We first provide an overview of the factors governing the electrocatalytic performance of Rh and Rh-based electrocatalysts, followed by highlighting four efficient strategies to significantly improve the electrocatalytic performance of Rh-based nanostructures, including atomic size design, composition optimization, morphology design, and surface/interface engineering. Finally, the challenges and future perspectives of Rh-based nanocatalysts are also presented to provide valuable insights for promoting the electrocatalytic performance for Rh-based electrocatalysts toward energy-conversion-related electrocatalytic reactions. [Display omitted] • A comprehensive review of the recent progress of Rh electrocatalysts is organized. • An overview of the factor governing the electrocatalytic performance of Rh-based electrocatalyst is summarized. • Five strategies to improve the electrocatalytic performance of Rh-based nanostructures are also discussed. • The future direction and perspective of this interesting field are also manifested. [ABSTRACT FROM AUTHOR]

The utilization of heterostructures as photocatalysts for water decomposition is a promising method to tackle contemporary environmental challenges. This research paper presents the design of a direct Z-scheme heterostructure utilizing a monolayer of GeC and a monolayer of arsenene, based on first-principle calculations. The photocatalytic efficiency of this GeC/arsenene van der Waals (vdW) heterostructure in a direct Z scheme has been investigated. The presence of a built-in electric field from the GeC monolayer to the arsenene monolayer has been established through an analysis of band alignment, work function, charge density, and Bader charge. The GeC/arsenene heterostructure exhibits excellent and robust optical absorption efficiency for the sunlight, alongside achieving the maximum solar-to-hydrogen (STH) energy conversion efficiency, amounting to 7.28%, under a biaxial strain of +4%. Furthermore, the Gibbs free energy changes in the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) of the GeC/arsenene heterostructure have been calculated. The outcomes indicate that the GeC/arsenene heterostructure is a feasible semiconductor for photocatalytic water splitting. Band edge positions and Z-scheme photocatalytic mechanism of the GeC/arsenene heterojunction. [Display omitted] • GeC/arsenene heterostructure has a built-in electric field from GeC to arsenene layer. • GeC/arsenene heterostructure exhibits a high optical absorption under biaxial tensile strain. • The highest solar-to-hydrogen efficiency of 7.28% is obtained under +4% strain. • High catalytic activity for the hydrogen evolution reaction is confirmed by free energy calculations. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFCs) are promising devices for clean and efficient energy conversion. However, SOFCs require high-quality electrolytes that can transport ions and separate gases. Pulsed laser deposition (PLD) is a physical vapor deposition (PVD) technique that can produce thin and dense films with tailored microstructure and composition. In this review, the advantages of PLD over other techniques are highlighted, such as reducing pinholes, forming columnar electrolyte particles, and creating heterogeneous structures. Different types of electrolytes fabricated by PLD for SOFCs are reviewed, such as oxygen ion conducting and proton conducting electrolytes. The influence factors of PLD in the electrolyte deposition process, such as substrate temperature, chamber pressure, and lattice strain, are discussed. The structure, function, and performance of different types of electrolytes made by PLD in SOFCs, such as oxygen ion conducting and proton conducting electrolytes are overviewed. We provide a comprehensive overview of PLD technology for SOFC electrolyte fabrication and optimization, and suggest future directions for research. [Display omitted] The pulsed laser deposition (PLD) technology for producing various types of thin and dense electrolyte films with different structures and functions are overviewed for improving the performance and durability of solid oxide fuel cells (SOFCs). • Provided a comprehensive overview of PLD technology for SOFC electrolyte fabrication and optimization. • Reviewed the advantages and applications of pulsed laser deposition (PLD) for SOFC electrolyte fabrication and optimization. • Discussed different types of electrolytes fabricated by PLD for SOFCs and their structure, function, and performance. • Analyzed the influence factors of PLD in the electrolyte deposition process. [ABSTRACT FROM AUTHOR]

The utilization of isopropanol-butanol-ethanol (IBE) to clean energy effectively mitigated the problems of environmental pollution and sustainable energy regeneration. In order to improve the utilization efficiency of ethanol and isopropanol in IBE, a liquid double-layer porous media burner was designed. And the combustion characteristics with different porous pellets and isopropanol ratios were studied. The results indicated that the mole fraction of hydrogen decreased with the increasing pellet diameter, and the lower heating value of syngas reached the highest value of 82.0 MJ/Nm3 when the pellets possessed two holes. Meanwhile, the peak temperature reached the maximum of 1009 K when the water content was 20% due to the sufficient combustion. And the isopropanol was conducive to the improvement of the total energy conversion efficiency. In addition, the yields of hydrogen and carbon monoxide were improved by 23.7% and 30.5% when the velocity increased from 10 to 12 cm/s. These results showed that the combustion of ethanol and isopropanol in porous media burners achieved the sustainable production of hydrogen and efficient utilization of IBE biofuels. [Display omitted] • Isopropanol and ethanol were combined with porous media for hydrogen production. • Hydrogen production was greatly improved with isopropanol addition than n-propanol. • 15% isopropanol and 85% ethanol obtained the energy conversion efficiency of 96.0%. • Increasing the hole number in porous pellet reduced the combustion temperature. [ABSTRACT FROM AUTHOR]

Solid Oxide Fuel Cell (SOFC) is an energy conversion technology featuring high efficiency, power density, durability, and fuel compatibility. In practice, however, SOFCs reach high power and high efficiency at different operating conditions. Hence, the optimal feasible operating condition is not straightforward and requires optimization. To resolve this problem, an accurate pretrained Physics-Informed Neural Network (PINN) model was developed as a surrogate of a 2D multi-physics model. For calibration, a planar SOFC with a 10 × 10 cm2 active area was tested at varied operating conditions. The resulting voltage error of the surrogate model was as low as 0.513%. The average runtime of the PINN model was 0.5 ms per case. Moreover, the PINN model accepts cell performance parameters as input and is therefore highly flexible. The surrogate was thereafter employed to generate performance maps that visualize the steady operating states at each combination of H 2 flowrate and operating voltage. The voltages of peak power points and anode-safety boundaries were plotted as functions of H 2 flowrate, so that the optimal operating conditions are shown graphically and can be tracked conveniently as the cell degrades. Further studies involving hydrocarbon fuels will be carried out in the future. [Display omitted] • An accurate pre-trained PINN model for real-time operating condition optimization. • Flexibility of the PINN model accepting cell performance parameters as input. • Straightforward visualization of operating states with performance maps. • Operating condition optimization with respect to anode-oxidation safety boundary. [ABSTRACT FROM AUTHOR]

Electrochemical energy conversion (via water splitting) and storage (via supercapacitors) are emerging strategies for developing the renewable energy sector; nevertheless, the hunt for low-cost and effective electrode material is a bottleneck issue. Herein, a bimetallic manganese nickel hydroxide was electrodeposited on Ni-foam without polymeric binder, followed by calcination to reveal its oxide configuration. As prepared, manganese nickel hydroxide (MnNi-hydroxide) displayed low Oxygen evolution reaction (OER) and Hydrogen evolution reaction (HER) overpotentials of 231 mV and 327 mV at 10 mA/cm2 during electrochemical water splitting, along with a superior turnover frequency of 0.12 sec−1 and 0.056 sec−1, respectively. Theoretical investigations revealed an increase in MnNi-hydroxide activity due to synergistic electronic interaction between Mn and Ni. Further, the MnNi-hydroxide, having high specific capacitances of 1174 mF/cm2 at 2 mV/s and 308 mF/cm2 at 1 mA/cm2, demonstrated a retention capacity of 98.9% over 5000 cycles. [Display omitted] • A bimetallic Mn-Ni hydroxide was electrodeposited on Ni-foam without polymeric binder. • Mn-Ni hydroxide displayed low OER and HER overpotentials of 231 mV and 327 mV at 10 mA/cm2. • This material also showed high specific capacitances of 1174 mF/cm2 at 2 mV/s and 308 mF/cm2 at 1 mA/cm2. • The synergistic interaction between Mn and Ni is a crucial factor in the efficient bifunctional activity. [ABSTRACT FROM AUTHOR]

Here in, we report a new methodology for the fabrication of free template ternary ZnO-CdS-Ag 2 S nanohybrids with superior photocatalyst properties for the hydrogen evolution reaction (HER) and dye degradation. Firstly, ZnO nanorods (NRs) were synthesized using a solvothermal method and used as a seed template for the growth of CdS-Ag 2 S QDs. The CdS-Ag 2 S QDs were grown using two different methods of microwave irradiation and photochemical treatment using thioglycolic acid (TGA) as both capping agent and digestive reactant. Structural characterizations proved the formation of the ternary structure with both methods of synthesis. XPS analyses revealed that photochemical approach results in the formation of a ternary composite with higher ZnO nanoparticles concentration. Electrochemical studies inferred that samples prepared using photochemical treatment have the least of charge transfer resistance, large surface area of 132 m2/g, large electrochemical surface area and higher electrochemical performance. Linear sweep voltammetry obtained current densities of magnitude of 100 mA cm−2 at bias −0.475 V vs. RHE, onset potential of −0.238 V, and Tafel slope of 45 mV/dec. Moreover, samples prepared using photochemical approach showed also high cyclic HER stability and reproducibility of the same results from the same ink after storing for six months. This method of synthesis can be applied for the synthesis of multi-functional ternary metal oxide-QD-QD nanocomposites for energy conversion applications. A S-scheme band diagram is suggested to infer the internal charge separation mechanism and high HER and photocatalyst activities of the ternary compound. [Display omitted] • New methodology for the synthesis of ZnO-CdS-Ag 2 S nanohybrids. • Nanohybrids show excellent Jsc of −100 mA cm−2 at 0.475 V vs. RHE, and Tafel slope of 45mV/dec. • Electrophotocatalyst activities of samples synthesized with UV treatment were superior. • Thioglycolic acid is a dual agent: capping agent for CdS/Ag2S and digestive for ZnO nanorods. • Prepared ink of the samples stored for 6 months showed high stability in their HER activity. [ABSTRACT FROM AUTHOR]

Al-based alloy ingots are a highly promising material for on-demand hydrogen supply. However, the use of Sn in them restricts the recovery and reuse of alloying elements, and also decreases the purity of byproducts, resulting in a significant increase in the application cost. Herein, a series of Sn-free ternary Al-alloys are prepared and their hydrogen production performance are investigated. Experimental results indicate that the Sn-free Al-Ga-In alloys maintain good hydrogen production performance, and the hydrolysis reaction is more stable and sustained than that of Al-Ga-In-Sn alloys. As the optimized formula, the 94Al-4.73Ga-1.27In alloy exhibits a high hydrogen conversion efficiency of 97.3% and an extremely stable average hydrogen production rate of 0.01423 L/min at 50 °C. In addition, a semi-coherent phase boundary-derived activation mechanism during Al hydrolysis was proposed. This study opens up a prospect for the development and large-scale using of recyclable Al-based on-demand hydrogen supply materials. [Display omitted] • Recyclable Sn-free Al-based alloys are developed for on-demand hydrogen supply. • Optimized alloys show stable H 2 production rate and achieve 97.3% energy conversion. • The hydrolysis reaction of Sn-free Al alloys is activated by the liquid phase. • Semi-coherent phase boundaries promote the hydrolysis reaction of alloys. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials have driven great interest due to a large specific surface area to volume ratio and adjustable surface behaviors, which show huge potentials for enhancing the activity of energy conversion and property optimization. In order to regulate the physicochemical properties of photocatalyst for water splitting reaction, defect engineering on 2D materials have drawn great attention. Meanwhile, a widely used strategy to improve the H 2 evolution rate kinetics has been achieved. In this paper, we prepared AgBr/g-C 3 N 4 catalyst by chemical precipitation. The obtained photocatalyst shows a unique charge transfer pathway. In addition, a deep understanding of the proton shuttle during H 2 evolution reactions can offer profound opinion into heterostructure construction and property optimization. It is found that the enhanced performance is correlated to the superiority of the S-scheme heterojunction and defect engineering on graphitic carbon nitride 2D materials. This work offers a novel method for improving efficiency in terms of energy conversion and property optimization. [Display omitted] • Surface nitrogen vacancy is instrumental in the chemisorption and activation of H 2 O. • S-scheme band of AgBr/g-C 3 N 4 is conjectured by the experiments and DFT calculations. • The prolonged photocarrier lifetime has increased H 2 production. • The results of XPS are consistent with the mechanism of S-scheme heterojunction. [ABSTRACT FROM AUTHOR]

The detrimental impact of human activity on the global ecological situation has resulted in the active exploration and development of alternative energy sources. Efficient solar energy utilization can significantly contribute to resolving the current energy crisis, because approximately 1.36 kW m−2 of solar radiation reaches the Earth's surface, and this can be used to satisfy the global energy requirements. Among various prevalent sunlight conversion technologies, photocatalytic materials are potentially useful for hydrogen production and other relevant applications. Existing technologies for the production and use of photocatalysts do not sufficiently address the target characteristics owing to the low solar conversion efficiency and service life in addition to high costs. However, recent advances in SrTiO 3 -based heterostructures indicate that photocatalysts can potentially compete with modern solar energy technologies in terms of their practical application. In this review, we systematically consider the advancement in the production and application of SrTiO 3 -based photocatalysts in various fields. The methods for obtaining complex heterostructures with different classes of nanomaterials are comprehensively discussed. The aim of this review is to highlight the advantages and limitations of using SrTiO 3 -based photocatalytic systems. Finally, the future prospects of using SrTiO 3 -based photocatalysts are considered from the perspective of their practical applications. [Display omitted] • The main strategies to overcome the limitations of SrTiO 3 based photocatalysts in various applications are presented. • The synthesis methods of composites based on SrTiO 3 for photocatalytic applications were discussed. • The potential applications of SrTiO 3 -based composites in solving environmental and energy-related problems are explored. [ABSTRACT FROM AUTHOR]

The core of this work is a comprehensive investigation of ethanol oxidative reforming kinetics over a Pt–Ni/CeO 2 –Al 2 O 3 catalyst in the presence of fuel grade bioethanol, which has been very rarely investigated in the past. The developed kinetic model also included the formation of solid carbon. The results show that the reaction scheme involving ethylene and acetaldehyde formation from ethanol, their subsequent decomposition, methane oxidation as well as steam reforming and water gas shift reaction is able to assure a satisfactory fitting of the experimental data. Moreover, the above formulation, deposited on a porous support (Ni–Fe foam), was employed for a very long stability test (almost 400 h) and subjected to several oxidation-reduction cycles: at 600 °C, after 170 h of time-on-stream, a stable ethanol conversion of 95% and hydrogen yield of 35% were recorded, with near-zero carbon emission during its thermochemical conversion for energy generation. • Investigation of Pt–Ni/CeO 2 –Al 2 O 3 kinetics for fuel grade ethanol reforming. • Integration of solid carbon and low-concentrated species in the kinetic model. • Very satisfactory fitting of the experimental data between 300 and 550 °C. • Considerable stability of the catalytic formulation deposited on a foam carrier. [ABSTRACT FROM AUTHOR]

Logistic fuels such as JP-8 diesel continue to hold importance as energy carriers for strategic applications due to their energy density and wide availability. For fuel cell system applications, such logistic fuels must be reformed on board to syngas; whereas, the catalytic reforming of commercial or military grade liquid fuels presents numerous challenges. In this study, we examine the possibility of increasing the conversion and energy efficiency of a non-catalytic diesel autothermal reformer by introducing a relatively homogenous mixture into the reactor. We achieve the mixing through two methods: one involving a reacting pre-mixer and the other with a non-reacting pre-mixer. Results demonstrate that a non-reacting pre-mixer enhances energy efficiency by up to 12% points, while increasing the conversion efficiency to nearly 88%. We expect further improvement in both conversion and energy efficiencies once design modifications are carried out to the pre-mixer such that lower residence times and higher ignition delays can be achieved. • Experiments on non-catalytic autothermal reformer with pre-mixer enhances efficiency. • Non-catalytic ATR can reform liquid fuel with sulfur, unlike catalytic reformers. • Results demonstrate that pre-mixer can significantly improve efficiency. [ABSTRACT FROM AUTHOR]

The development of electrocatalysts for electrochemical water splitting has received considerable attention in response to the growing demand for renewable energy sources and environmental concerns. In this study, a simple hydrothermal growth approach was developed for the in-situ growth of non-stoichiometric CrO 0.87 and Co 3 O 4 hybrid materials. It is apparent that the morphology of the prepared material shows a heterogeneous aggregate of irregularly shaped nanoparticles. Both CrO 0.87 and Co 3 O 4 have cubic crystal structures. Its chemical composition was governed by the presence of Co, Cr, and O as its main constituents. For understanding the role CrO 0.87 plays in the half-cell oxygen evolution reaction (OER) in alkaline conditions, CrO 0.87 was optimized into Co 3 O 4 nanostructures. The hybrid material with the highest concentration of CrO 0.87 was found to be highly efficient at driving OER reactions at 255 mV and 20 mA cm−2. The optimized material demonstrated excellent durability for 45 h and a Tafel slope of 56 mV dec−1. Several factors may explain the outstanding performance of CrO 0.87 and Co 3 O 4 hybrid materials, including multiple metallic oxidation states, tailored surface properties, fast charge transport, and surface defects. An alternative method is proposed for the preparation of new generations of electrocatalysts for the conversion and storage of energy. • Hydrothermally non-stoichiometric CrO 0.87 and Co 3 O 4 hybrid system was prepared. • CrO 0.87 and Co 3 O 4 hybrid system showed an enhanced OER activity. • A low overpotential for OER reaction was about 255 mV at 20 mA/cm2. • The CrO 0.87 and Co 3 O 4 hybrid system was highly durable for 45 h. [ABSTRACT FROM AUTHOR]

The development of earth abundant electrocatalysts for high performance hydrogen evolution reaction (HER) is highly desirable in energy conversion system. Transition metal phosphide has been exploited to promote electrochemical performance due to its unique heterointerface, outstanding conductivity, and a wide pH range tolerance. Herein, we employ a facile hydrothermal approach to build a heterojunction interface modulated coral-like NiCoP electrocatalyst with favorable crystalline surface, minimal charge transfer resistance, and excellent electron transfer for outstanding HER. In alkaline media, the optimum NiCoP electrocatalyst demonstrates excellent HER performance with an overpotential of 215 mV and Tafel slope of 82 mV dec−1 at 10 mA cm−2. This benefits from the formation of heterojunction with exposed active sites, redistributed electrons and altered coordination environment. The combined experimental results and density functional theory (DFT) investigations demonstrate that heterojunction interfaces are beneficial for lowering the Gibbs free energy of hydrogen adsorption (ΔG H∗), hence boosting HER dynamics process. This study presents a feasible approach for the preparation of low-cost, high-efficiency NiCoP electrocatalysts for HER, which is particularly appealing for practical applications. • Coral-shaped NiCoP electrocatalyst was prepared from one-step hydrothermal method. • NiCoP heterojunctions shows a superior hydrogen evolution reaction than Ni 2 P, Co 2 P. • The favorable (111) crystal plane was exploited to enhance HER performance. • Density functional theory reveals a lowered ΔG H ∗ of heterojunction interfaces to boost HER. [ABSTRACT FROM AUTHOR]

The scientific community is currently very interested in energy and environmental concerns. Due to their distinctive features, two-dimensional materials have drawn a lot of interest for technological applications. The MXene family of 2D materials, which is expanding quickly, has many advantages in energy and storage due to its excellent physiochemical properties. This study covers important developments in the area of 2D MXene and talks about how design, synthetic methods, and stability have changed over time. In addition to emphasizing the state-of-the-art applications, we also discuss the challenges and limitations facing the scientific community in the development of functional MXene with controlled structures and properties for renewable clean energy conversion and storage applications. Finally, the key issues and considerations that will shape the future of these 2D MXene-based materials in energy storage applications are described. [ABSTRACT FROM AUTHOR]

Conversion of renewable energy sources like bioethanol to electricity using solid oxide fuel cells (SOFCs) is promising to reduce the consumption of fossil fuels and to mitigate global warming. However, direct ethanol-fed SOFCs are susceptible to carbon deposition on Ni-based anode. In this study, the power generation from and degradation mechanism of large-scale flat-tube SOFCs by direct internal reforming of ethanol are investigated. The steam/carbon (S/C) ratio causes minor influence on the cell performance but considerably affects the long-term durability. Elevating temperature improves ethanol conversion rate and cell performance. Ethanol is efficiently reformed by the thick anode support and long anode channels, with low selectivity for CH 4 and C 2 H 4. Stable power generation with current density of 200 mA/cm2 is obtained over 300 h under S/C = 2 and 3 at 800 °C. Due to the high operating temperature and complex cell structure, the in-situ measurements of the temperature and gas compositions within the cell, related to carbon deposition, are difficult. The distributions of the gas compositions and temperature within the cell before and after the durability test are clarified by simulation. Simulation results reveal that, in addition to CH 4 and C 2 H 4 , the cold zone near inlet contributes to carbon formation. • Power generation of large-scale direct ethanol-fed flat-tube SOFCs were studied. • Over 300 h stable operation was achieved under S/C = 2 and 3 at 800 °C. • The coking distribution and fields of temperature and composition were clarified. • The performance degradation was derived from coking and Ni agglomeration. • The decrease of local temperature near the inlet aggravated the carbon deposition. [ABSTRACT FROM AUTHOR]

To enhance the efficiency of energy utilization, a novel combined system incorporating a high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC), an intermediate band thermoradiative device (IBTRD), and a regenerator is established, where the IBTRD can efficiently exploit the exhaust heat from HT-PEMFC to produce extra power. Based on electrochemistry, semiconductor theory, and the non-equilibrium thermodynamics the mathematical expressions for power density and energy conversion efficiency (ECE) for the integrated device are gained. Meanwhile, considering the multiple irreversible losses, the relationship between the IBTRD voltage and the HT-PEMFC operating current is obtained, and the optimal working regions for key parameters about the presented model are identified. The numerical results demonstrate that the combined model's maximum power density (MPD) and its corresponding energy conversion efficiency are 0.49 W/cm2 and 24.57%, which are respectively 25.61% and 27.52% bigger than those of the single HT-PEMFC. Additionally, it is revealed how vital parameters affect the performance characteristics of the combined model, including the doping level, operating temperature, relative humidity, operating pressure, and the bandgap of IBTRD. The conclusion indicates that an enhancement in MPD from 0.428 W/cm2 to 0.538 W/cm2 and an increase in ECE from 0.224% to 0.255% as the temperature enhances from 423 K to 463 K. The outcomes acquired may be valuable for the design and development of such a true combination system. • A hybrid system consisting of a HT-PEMFC and an IBTRD is established. • The HT-PEMFC waste heat is recycled to produce extra power by IBTRD. • Performance indicators for the hybrid system are mathematically formulated. • The effect of some operating parameters on the system performance is revealed. • The overall performance is significantly improved compared to the single HT-PEMFC. [ABSTRACT FROM AUTHOR]

The development of multifunctional electrocatalysts is crucial for enhancing the efficiency of electrochemical conversion in energy devices. Here we have synthesized TiO 2-x nanosheets (NSs) supported metallic Pd nanoparticles (Pd/TiO 2-x NSs) as an electrocatalyst using a simple impregnation process. High electrochemical surface areas (ECSAs) and strong metal support interactions (SMSI) of the electrocatalyst showed improved ORR performance throughout a wide pH range under ambient conditions. The outstanding durability of the catalyst was proven by the square-wave potential cycling experiment at 60 °C. Additionally, it was shown that Pd/TiO 2-x NSs showed improved HER activity and stability in 0.5 M H 2 SO 4. The catalyst had an overpotential of 19.5 mV for the 10 mA cm−2 and a low Tafel slope of 41 mV dec−1. The catalyst also showed higher stability for about 30 h in HER performance. This work will help in rationally building nanostructured electrocatalysts loaded on carbon-free support for efficient electrochemical energy storage devices. [Display omitted] • We developed a TiO 2-x nanosheet (NS) coupled Pd nanoparticle electrocatalyst. • SMSI effect improved the electrocatalytic performance of the Pd/TiO 2-x NSs catalyst. • The catalyst demonstrated remarkable bifunctionality in both ORR and HER. • Additionally, the material displayed an exceptional long-trem performance. • For energy storage devices, TiO 2-x nanosheets serve as an alternate carbon-free support. [ABSTRACT FROM AUTHOR]

Towards the next-gen energy solutions, Nafion, as a state-of-the-art polymer electrolyte to low temperature fuel cell (LTFC) application has been one of the most demanding hydrogen to clean energy conversion device ever achieved. However, the inherent issue of limiting chemical durability and restricted proton conductivity have always been a topic of concern with pure Nafion membranes. To tackle this, we report a mixed-ceria reinforced phosphorylated graphene oxide (sPGO)/Nafion membrane as a potential electrolyte to simultaneously improve the chemical durability and proton conductivity of bare Nafion by utilizing the redox property of ceria nanoparticles and acidic sites of sPGO for accelerated proton transfer. As a progressive method, the single-step phosphorylation of GO introduced short chain branching along with enhanced number of acidic sites in the Nafion matrix whereas incorporation of mixed-ceria nanoparticles improved the chemical durability of the membrane due to its superior radical scavenging property. As a result, mixed-ceria reinforced sPGO/Nafion (Ce-sPGO/NF) electrolyte membrane showed higher proton conductivity (1.2-times) and chemical durability (8.1-times) than bare Nafion. Furthermore, the polymer electrolyte membrane (PEM) was also showcased high enough thermomechanical and electrochemical stability at 80 °C and 100% relative humidity (RH). • A novel mixed ceria decorated sPGO nanocomposite was prepared. • Ce-sPGO incorporation to Nafion uplifted the membrane chemical durability. • Enhanced physicochemical, thermomechanical, and electrochemical properties noticed. • Comparatively enhanced proton conductivity at actual fuel cell conditions. • Detailed demonstration of possible mechanism behind enhanced performance. [ABSTRACT FROM AUTHOR]

A simple oxidative polymerization approach has been used to synthesize MoO 3 /PANI hybrid composite for energy conversion and storage application. In this carbon-free energy conversion process, as-developed electrocatalyst (MoO 3 /PANI hybrid composite) has significantly improved the molecular hydrogen generation via electro-reduction of protons. The hydrogen evolution kinetics parameters, overpotential at 10 mA cm−2 is ∼110 mV and Tafel slope 132 mV/dec have been obtained for the as-developed catalyst which suggests the reaction is controlled by Volmer-limited reaction step. Further the as-developed material has been tested for energy storage application and exhibited specific capacitance of 680 F. g−1. [Display omitted] • Development of MoO 3 /PANI hybrid composite involves facile one step oxidative polymerization. • MoO 3 /PANI Hybrid Composite exhibited significant dual function in HER and supercapacitor. • MoO 3 /PANI needs merely 110 overpotential to deliver 10 mA/cm2 with small Tafel slope (132 mV/dec) and improved specific capacity (680 F/g). • Efficient HER and supercapacitor performance observed due to harmonious relation between MoO 3 and conducting polymer. [ABSTRACT FROM AUTHOR]

MnO 2 is considered to be one of the most promising electrocatalysts for oxygen reduction reactions (ORR) in alkaline media and can be applied to various electrochemical energy conversion and storage devices. However, it is limited by the relatively slow kinetics of the cathodic electrochemical reactions. In addition, it is difficult to control the presence state of Ag during the modification of MnO 2. To this end, an efficient ORR electrocatalyst of Ag nanoparticles supported by MnO 2 nanorods was successfully synthesized by using NH 3 ·H 2 O as a complexing agent to inhibit the Ag+ intercalating into the tunnels of MnO 2. The half-wave potential (E 1/2) and limiting current density (J lim) of the obtained Ag/MnO 2 electrocatalysts are 0.81 V and −5.6 mA cm−2, respectively, showing comparable ORR catalytic activity to commercial Pt/C catalysts. The excellent catalytic performances can be attributed to the presence of abundant oxygen vacancies and Mn3+ species on the MnO 2 surface, as well as the synergistic effect between MnO 2 substrates and Ag nanoparticles. Among them, oxygen vacancies enhances the adsorption of O 2 , Mn3+ facilitates the displacement of O 2 2−/OH−, MnO 2 inhibits the accumulation of peroxide species to improving the oxygen environment on the Ag surface and Ag accelerates the electron transfer in the whole process. This work provides a useful guide for the design of efficient Mn-based ORR electrocatalysts. [Display omitted] • NH 3 ·H 2 O inhibits the diffusion of Ag+ and facilitates the synthesis of Ag/MnO 2. • The excellent activity is due to the synergistic effect between MnO 2 and Ag. • O V improves the O 2 adsorption and Mn3+ facilitates the O 2 2−/OH− displacement. • A green and efficient way was adopted to the scale synthesis of ORR catalyst. [ABSTRACT FROM AUTHOR]

The development of high-performance and stable trifunctional electrocatalysts is a pressing challenge for the practical application of water splitting and regenerative Zn-air batteries. Herein, bamboo-like N-doped carbon tubes encapsulated Co 2 P–Fe 2 P nanoparticles (CoFe-PN/C) was fabricated via a facile template-sacrificial approach by using CoZn-ZIF trapping Fe3+ (CoFeZn/C) as the precursor. The incorporation of Fe3+ was achieved by the one-pot synthesis approach during crystallization of ZIF, which led to the generation of the unique bamboo-like tube structure under the condition of simultaneous phosphating and carbonization. Benefiting from the large surface area, the optimized electronic structure of active sites and the unique bamboo-like nanotube, the resultant CoFe-PN/C can be used as the trifunctional electrocatalyst possessing a small overpotential at 10 mA cm−2 for the HER (178 mV) and OER (300 mV), as well as a high half-wave potential of 0.884 V for ORR (40 mV more positive than that of commercial 20 wt% Pt/C). Moreover, the self-designed CoFe-PN/C||CoFe-PN/C alkaline electrolyzer driving 50 mA cm−2 only need operating potential of 1.84 V and the maximum discharge power density of the CoFe-PN/C-assembled ZABs could achieve 152.0 mW cm−2, superior to those of Pt/RuO 2 couple. This work will facilitate the development and application of trifunctional electrocatalysts based on bi-transition metallic phosphides for energy conversion and storage technology. [Display omitted] • A facile method is reported for preparing bamboo-like nanoparticles. • One-pot synthesis is demonstrated to trap Fe3+ into CoZn-ZIF. • Bamboo-like tube structure is more favorable for exposing active species. • Optimized catalyst shows trifunctional activity to HER, OER and ORR. [ABSTRACT FROM AUTHOR]

Alkaline Earth free spinel oxides provide a potential benefit over Sr-doped perovskite-based materials commonly used as electrodes in high-temperature electrochemical energy conversion devices, e.g., solid oxide fuel cells (SOFCs). Sr-segregation is a known issue leading to performance degradation. In this study, Cu x Mn 3-x O 4 (x = 1, 1.2, and 1.5) porous electrodes were examined as SOFC cathodes using electrochemical impedance spectroscopy to investigate the oxygen reduction reaction (ORR) kinetics in relation to the material's intrinsic conductivity, the extrinsic electrode structure, and the cell test design. Similar to the electronic conducting (La,Sr)MnO 3 SOFC cathodes, the ORR kinetics of Cu x Mn 3-x O 4 spinel electrodes was governed by the oxygen adsorption and diffusion at the particle surface as well as the charge transfer at the triple phase boundaries. The overall electrode polarization resistance was highly dependent on contact density with the metallic current collector, active material particle connectivity, electrode thickness, and the intrinsic electronic materials conductivity. We describe the importance of effective electronic charge transport parallel to the electrode surface in maximizing the electrochemically active electrode volume and enhancing electrode performance. We discuss an approach to optimize cell and electrode design with respect to active materials properties. This aspect is critical to ensure reliable evaluation of new materials, since laboratory-scale button-cells typically exhibit a high degree of electrode microstructure (e.g. porosity, thickness) and electrical contact density variation from sample to sample. • Understanding of oxygen reduction reaction kinetics in porous spinel electrode. • Influence of electronic transport on oxygen reduction reaction kinetics. • More electrical contact points for enhanced oxygen reduction activity. • Higher particle electronic conductivity for enhanced oxygen reduction activity. • Better particle connectivity for enhanced oxygen reduction activity. [ABSTRACT FROM AUTHOR]

As clean energy conversion devices with the functions of power generation and hydrogen evolution, solid oxide cells (SOCs) are facing the obstacle of insufficient catalytic activity of traditional electrode materials under the trend of lower operation temperature. Here a double-perovskite material PrBa 0.5 Sr 0·5 Co 2-x Fe x O 5+δ (PBSCF, x = 0.5, 1.0, 1.5, 2.0) is reported and its application as oxygen electrode of symmetrical cells on the proton conductor BaZr 0·1 Ce 0·7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb1711) is investigated. The tests are carried out under atmospheres with different water content (0, 20% and 40%), showing the influence of Fe/Co molar ratio on the crystal structure, conductivity, electrochemical properties and micro morphology of PBSCF series materials. With the increasing of Fe substitution content, the polarization resistance of PBSCF series symmetrical cells decreases. PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ (PBSCF05) symmetrical cell always shows the optimal performance and exhibits area-specific polarization resistance (ASR) of 0.08 Ω cm2 at 700 °C under 20%H 2 O+80%air. Further experimental results and the distribution of relaxation times (DRT) analysis show that the presence of an appropriate amount of steam in atmosphere would optimize the conductive mechanism and promote proton migration, while the presence of excessive steam would hinder the diffusion of oxygen molecule. For the electrochemical reaction on the PBSCF electrode, the adsorption, dissociation and precipitation of oxygen are always the crucial rate-limiting steps, which is a direction worthy of further optimization. [Display omitted] • PrBa 0.5 Sr 0·5 Co 2-x Fe x O 5+δ (x = 0.5, 1.0, 1.5, 2.0) is promising oxygen electrode of H–SOC. • The series materials were synthesized successfully by GNP. • The series materials' conductivity were tested under air with different water content (0, 20% and 40%). • PrBa 0.5 Sr 0·5 Co 1·5 Fe 0·5 O 5+δ (PBSCF05) symmetrical cell always shows the best performance. [ABSTRACT FROM AUTHOR]