Search

Homogeneous solar fuels photocatalytic systems often require several additives in solution with the catalyst to operate, such as a photosensitizer (PS), Brønsted acid/base, and a sacrificial electron donor (SED). Tertiary amines, in particular triethylamine (TEA) and triethanolamine (TEOA), are ubiquitously deployed in photocatalysis applications as SEDs and are capable of reductively quenching the PS's excited state. Upon oxidation, TEA and TEOA form TEA•+ and TEOA•+ radical cations, respectively, which decay by proton transfer to generate redox non-innocent transient radicals, TEA• and TEOA•, respectively, with redox potentials that allow them to participate in an additional electron transfer step, thus resulting in net one-photon/two-electron donation. However, the properties of the TEA• and TEOA• radicals are not well understood, including their reducing powers and kinetics of electron transfer to catalysts. Herein, we have used both pulse radiolysis and laser flash photolysis to generate TEA• and TEOA• radicals in CH3CN, and combined with UV/Vis transient absorption and time-resolved mid-infrared spectroscopies, we have probed the kinetics of reduction of the well-established CO2 reduction photocatalyst, fac-ReCl(bpy)(CO)3 (bpy = 2,2′-bipyridine), by these radicals [kTEA• = (4.4 ± 0.3) × 109 M−1 s−1 and kTEOA• = (9.3 ± 0.6) × 107 M−1 s−1]. The ∼50× smaller rate constant for TEOA• indicates, that in contrast to a previous assumption, TEA• is a more potent reductant than TEOA• (by ∼0.2 V, as estimated using the Marcus cross relation). This knowledge will aid in the design of photocatalytic systems involving SEDs. We also show that TEA can be a useful radiolytic solvent radical scavenger for pulse radiolysis experiments in CH3CN, effectively converting unwanted oxidizing radicals into useful reducing equivalents in the form of TEA• radicals. [ABSTRACT FROM AUTHOR]

Hybrid fuel cell/gas turbine systems provide an efficient means of producing electricity from fossil fuels with ultra low emissions. However, there are many significant challenges involved in integrating the fuel cell with the gas turbine and other components of this type of system. The fuel cell and the gas turbine must maintain efficient operation and electricity production while protecting equipment during perturbations that may occur when the system is connected to the utility grid or in stand-alone mode. This paper presents recent dynamic simulation results from two laboratories focused on developing tools to aid in the design and dynamic analyses of hybrid fuel cell systems. The simulation results present the response of a carbonate fuel cell/gas turbine, or molten carbonate fuel cell/gas turbine, (MCFC/GT) hybrid system to a load demand perturbation. Initial results suggest that creative control strategies will be needed to ensure a flexible system with wide turndown and robust dynamic operation. Paper No. GT2004-53653,

Polymer membrane electrolyzers are a useful tool for producing hydrogen, which is a renewable energy source. Unmanned aerial vehicle (UAV) fuel cells can be powered by the hydrogen and oxygen produced by the electrolyzer. The primary losses of polymer membrane electrolyzers must therefore be identified in order to maximize their performance. A renewable-based multi-energy system considers power, cooling, heating, and hydrogen energy as utility systems for integrated sport buildings. In this study, we investigate the effect of radiation intensity, current density, and other performance factors on the rate of hydrogen production in water electrolysis using a polymer membrane electrolyzer in combination with a solar concentrator. The findings showed that a rise in hydrogen generation led to an increase in current density, which increased the electrolyzer's voltage and decreased its energy and exergy efficiencies. The voltage was also increased, and the electrolyzer's efficiency was enhanced by a rise in temperature, a decrease in pressure, and a reduction in the thickness of the nafion membrane. Additionally, with a 145% increase in radiation intensity, hydrogen production increased by 110% while the electrolyzer's energy and exergy efficiencies decreased by 13.8% as a result of the electrolyzer's high input electric current to hydrogen output ratio. [ABSTRACT FROM AUTHOR]

Anion-exchange membranes (AEMs) are a possible replacement for perfluorosulfonic-acid membranes in energy-conversion devices, primarily due to the hydroxide mobile ion allowing the devices to operate in alkaline conditions with less expensive electrocatalysts. However, the transport properties of AEMs remain understudied, especially electro-osmosis. In this work, an electrochemical technique, where the open-circuit voltage is measured between two ends of a membrane maintained at different relative humidities, is used to determine the water transport number of various ionomers, including Versogen and Sustainion AEMs and Nafion cation-exchange membrane (CEM), as a function of water content and temperature. In addition, the CEMs and AEMs are examined in differing single-ion forms, specifically proton and sodium (CEM) and hydroxide and carbonate (AEM). Carbonate-form AEMs have the highest transport number (∼11), followed by sodium-form CEMs (∼8), hydroxide-form AEMs (∼6), and proton-form CEMs (∼3). Finally, a multicomponent transport model based on the Stefan-Maxwell-Onsager framework of binary interactions is used to develop a link between water transport number and water-transport properties, extracting a range for the unmeasured membrane water permeability of Versogen as a function of water content.

Probing the chemistry and materials science of electrochemical energy materials is a central topic in both chemical physics and energy chemistry due to the increasingly important role of energy devices in the current and future energy system and industry. Especially, understanding the chemical physics of electrochemical energy materials is the key to enhance the performance of energy storage and conversion devices such as batteries, fuel cells, electrolyzers, and supercapacitors. This special topic focuses on the fundamental understanding of electrochemical energy applications, including electrochemistry fundamentals, structural dynamics and degradation mechanism of materials, optimization strategies for improving electrochemical performance of energy devices, and emerging simulation and characterization methods applied to advanced energy materials. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have drawn great attention as potential materials for energy conversion and storage systems such as batteries, supercapacitors, and fuel cells. Among these energy conversion and storage systems, the fuel cells had stood out owing to their high-power density, energy conversion efficiency and zero greenhouse gasses emission. In fuel cells, CNTs have been widely studied as catalyst support, bipolar plates and electrode material due to their outstanding mechanical strength, chemical stability, electrical and thermal conductivity, and high specific surface area. The use of CNT has been shown to enhance the electrocatalytic performance of the catalyst, corrosion resistivity, improve the transmission performance of the fuel cell and reduce the cost of fuel cells. The use of CNTs in fuel cells has drastically reduced the use of noble metals. However, the major drawback to the utilization of pristine CNTs in fuel cells are; poor dispersion, agglomeration, and insolubility of CNTs in most solvents. Surface engineering of CNTs and CNT nanocomposites has proven to remarkably remedy these challenges and significantly enhanced the electrochemical performance of fuel cells. This review discusses the different methods of surface modification of CNTs and their nanocomposite utilized in fuel cell applications. The effect of CNTs in improving the performance of fuel cell catalyst, membrane electrode assembly and bipolar plates of fuel cells. The interaction between the CNTs catalyst support and the catalyst is also reviewed. Lastly, the authors outlined the challenges and recommendations for future study of surface functionalized CNTs composite for fuel cell application.

Trade-off parameters (proton conductivity and chemical stability) among standalone and acceptor-doped proton-conducting electrolytes hinder their practical utility within the fuel cell technology. The physio and electrochemical divergence among the proton conducting electrolytes introduce thermionic singularity (fluctuation) due to multifacet contributions ranging from structural phase transitions to defect-cluster distribution. Meanwhile, lattice disorder (phonon contributions) and defect scattering events distort the charge transport characteristics of the host material. As a result, in the present study we address the thermionic response of standalone and Y3+ doped BaCeO 3 polymorph using first principles and classical molecular dynamics to contemplate proton landscape and dynamical disorder among aristotype and hettotype structures. The outcome of the study illustrates a promising thermionic behaviour among hettotype structures due to desirable potential energy surface with finite tunnelling probability relative to aristotype counterpart. As a result, a favourable response by BaCe 0.75 Y 0.25 O 3-δ (rhombohedral symmetry) at intermediate temperature (400–580 °C) occurs due to phonon aided proton transport, desirable proton landscape (O–O separation), weaker Y–O hybridization and high carrier concentration. However, thermionic fluctuations and contrary response at elevated temperatures (>600 °C) illustrate the advent of ambipolar characteristics (H+/O2−), cationic disorder (Ce4+ → Ce3+), defect scattering (V O.. ) event and local proton traps due to proton-polaron charge redistribution. As a result, the present study is essential to enhance the electrochemical kinetics and performance efficiency of proton conducting electrolytes. [Display omitted] [ABSTRACT FROM AUTHOR]

Bioelectro-Fenton (BEF) utilizes microorganisms to generate electrons at the anode and transfer them to the cathode via an external circuit to generate hydrogen peroxide (H 2 O 2) and drive the Fenton reaction to produce OH•. Response surface methodology was used to optimize the ratio of nano zero-valent iron-containing biochar and conductive carbon black (nZVI-biochar/CCB) with the chitosan-coated on the surface of the cathode material to promote H 2 O 2 production and reduce the internal resistance of the BEF system. The BEF system using the optimized cathode catalysts showed a 2.6-fold increase in power density and a 2.03-fold increase in open-circuit voltage over the BEF reaction using graphite felt cathodes only. This finding demonstrated that the optimized cathode improved the capability of the cathode to receive electrons. The BEF system with the optimized cathodic catalyst completely removed 400 mg/L isopropanol within 24 h, and the treated wastewater was almost nonbiotoxic. [Display omitted] • Microbial fuel cells produce electricity to drive the electro-Fenton (EF) process. • Bioelectro-Fenton (BEF) process removes isopropanol from wastewater. • Optimization of cathodic catalyst ratio improves H 2 O 2 generation in the EF system. • BEF system with optimized cathodic catalyst enhances power and isopropanol removal. [ABSTRACT FROM AUTHOR]

The environmental and societal challenges of our contemporary society are leading us to reconsider our approaches to vehicle design. The aim of this article is to provide the reader with the essential knowledge needed to responsibly design a vehicle equipped with a hydrogen fuel cell system. Two pivotal aspects of hydrogen-electric powertrain eco-design are examined. First, the global warming potential is assessed for both PEMFC systems and Type IV hydrogen tanks, accounting for material extraction, production, and end-of-life considerations. The usage phase was omitted from the study in order to facilitate data adaptation for each type of use. PEMFC exhibits a global warming potential of about 29.2 kgCO 2eq /kW, while the tank records 12.4 kgCO 2eq /kWh, with transportation factors considered. Secondly, the societal and governmental impacts are scrutinized, with the carbon-intensive hydrogen tank emerging as having the most significant societal and governmental risks. In fact, on a scale of 1–5, with 5 representing the highest level of risk, the PEMFC system has a societal impact and governance risk of 2.98. The Type IV tank has a societal impact and governance risk of 3.31. Although uncertainties persist regarding the results presented in this study, the values obtained provide an overview of the societal and governmental impacts of the hydrogen ecosystem in the transportation sector. The next step will be to compare, for the same usage, which solution between hydrogen-electric and 100% battery is more respectful of humans and the environment. • Platinum accounts for less than 0.01% of the mass in a fuel cell system. • A type IV hydrogen tank mass consists of over two-thirds carbon fiber one. • The societal impact of the tank is higher than that of the fuel cell system. • The global warming potential of the tank exceeds that of the fuel cell system. • Assessing societal impacts and governance risks involves inherent uncertainties. [ABSTRACT FROM AUTHOR]

Urea oxidation reaction (UOR) has garnered significant attention in recent years as a promising and sustainable clean‐energy technology. Urea‐containing wastewater poses severe threats to the environment and human health. Numerous studies hence focus on developing UOR as a viable process for simultaneously remediating wastewater and converting it into energy. Moreover, UOR, which has a thermodynamic potential of 0.37 V (vs reversible hydrogen electrode, RHE), shows great promise in replacing the energy‐intensive oxygen evolution reaction (OER; 1.23 V vs RHE). The versatility and stability of urea, particularly at ambient temperatures, make it an attractive alternative to hydrogen in fuel cells. Since UOR entails a complex intermediate adsorption/desorption process, many studies are devoted to designing cost‐effective and efficient catalysts. Notably, transition metal‐based materials with regulated d orbitals have demonstrated significant potential for the UOR process. However, comprehensive reviews focusing on transition metal‐based catalysts remain scarce. In light of this, the review aims to bridge the gap by offering an in‐depth and systematic overview of cutting‐edge design strategies for transition metal‐based catalysts and their diverse applications in UOR. Additionally, the review delves into the status quo and future directions, charting the course for further advancements in this exciting field. [ABSTRACT FROM AUTHOR]

Ni-based catalysts have been considered as an efficient anode material for urea fuel cells due to their low cost and high activity in alkaline media. Ni2P/NiCo2S4 catalyst grown on nickel foam was synthesized by hydrothermal synthesis and solid phosphating. The cathode material Pt/C was prepared using the drop-coating method, which has good oxygen reduction reaction (ORR) activity. H-type urea/O2 fuel cell was assembled and showed high energy density in alkaline solution at room temperature. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS) were employed to characterize the Ni2P/NiCo2S4/NF catalyst. Results confirmed the formation of 3D flower-like microspheres from Ni2P/NiCo2S4/NF catalyst nanosheets. Electrochemical testing results indicated that the Ni2P/NiCo2S4/NF catalyst-decorated electrode can effectively promote urea oxidation and plays a leading role in improving the performance of fuel cells in 1 M KOH + 0.33 M urea. The H-type urea/O2 fuel cell possesses a high power density of 0.42 mW cm−2 at a cell potential of 0.45 V. To summarize, this study introduces a cheap but efficient electrode material as an anode catalyst for constructing urea fuel cells. [ABSTRACT FROM AUTHOR]

Core–shell architectures provide great opportunities to improve catalytic activity, but achieving nanoparticle stability under electrochemical cycling remains challenging. Herein, core–shell nanoparticles comprising atomically thin Pt shells over earth‐abundant TaC cores are synthesized and used as highly durable electrocatalysts for the methanol oxidation reaction (MOR) and the oxygen reduction reaction (ORR) needed to drive direct methanol fuel cells (DMFCs). Characterization data show that a thin oxidic passivation layer protects the TaC core from undergoing dissolution in the fuel cell‐relevant potential range, enabling the use of partially covered Pt/TaC core–shell nanoparticles for MOR and ORR with high stability and enhanced catalytic performance. Specifically, at the anode the surface‐oxidized TaC further enhances MOR activity compared to conventional Pt nanoparticles. At the cathode, the Pt/TaC catalyst feature increases tolerance to methanol crossover. These results show unique synergistic advantages of the core–shell particles and open opportunities to tailor catalytic properties for electrocatalytic reactions. [ABSTRACT FROM AUTHOR]

A series of imidazolium-functionalized poly(phenylene oxide) (QPPO) cross-linked with polybenzimidazole (PBI) (cQPPOx-PBI) membranes were prepared. Compared to the pure PBI membrane without a cross-linked structure nor imidazolium groups, the cQPPOx-PBI membranes showed enhanced toughness, phosphoric acid (PA) retention, and chemical stability. The cQPPOx-PBI membranes showed a enhanced PA uptake than that of PBI membranes, and the cQPPO35-PBI membrane achieves a high conductivity of 139 mS cm−1 at 160 °C, which is much higher than that of PBI membrane under the same conditions (26 mS cm−1). The performance of the single fuel cell assembled with the obtained membranes showed a similar trend as their conductivity, and the cell with cQPPO35-PBI showed a maximum power density of 344 mW cm−2 at 140 °C, while the value for PBI membrane was only 175 mW cm−2 under the same conditions. Herein, a straightforward method was developed for introducing imidazolium groups and cross-linked structures, which can be employed to prepare PEMs with enhanced performance for HT-PEMFCs application. [Display omitted] • Poly(phenylene oxide) crosslinked with polybenzimidazole was designed and prepared. • The cross-linked membranes showed enhanced toughness, PA retention, and chemical stability. • The fuel cell comprising cQPPO35-PBI exhibited a maximum power density of 344 mW cm−2. [ABSTRACT FROM AUTHOR]

The integration of reformers into high-temperature polymer electrolyte membrane (HT-PEM) fuel cells presents a significant opportunity to improve fuel flexibility and cost-effectiveness. To understand their degradation, we applied two start–stop cycling procedures: one with pure H 2 and another with an 80 vol % H 2 and 20 vol % N 2 mix to simulate reformate gas. We also performed a load cycling test with H 2 as anode gas. The results indicated that degradation rate of pure H 2 start–stop cycling showed 306 μ V h−1, while load cycling demonstrated a degradation rate of 19.7 μ V h−1 for the current density of 0.2 A cm−2, and 88.2 μ V h−1 for the current density of 0.4 A cm−2. Start–stop cycling with diluted gas resulted in a constant voltage drop with a degradation rate of 3.129 mV h−1. Electrochemical impedance spectroscopy (EIS) indicated an increased ohmic resistance during start–stop cycling and higher charge transfer (high-frequency) and mass transport (low-frequency) resistance with nitrogen introduction. Scanning electron microscope results confirmed MEA degradation. In conclusion, start–stop cycling and anode gas dilution are stressors that accelerate HT-PEM fuel cell degradation, reducing its lifetime. • Start–stop and anode gas dilution degrade HT-PEM cells. • Degradation jumps from 306 μ V/h to 3.129 mV/h with dilution. • Low degradation (88.2 μ V/h) at 0.4 A/cm² under load cycling. • Anode dilution with nitrogen amplifies resistive effects. • SEM analysis confirmed physical degradation of MEA. [ABSTRACT FROM AUTHOR]

The durability of Polymer Electrolyte Membrane Fuel Cells under dynamic operation still needs to be improved. To understand the automotive voltage cycling-induced catalyst degradation, the loss of the electrochemically active surface area (ECSA) is investigated through an experimental campaign on Membrane Electrode Assemblies. Ad-hoc hydrogen/air accelerated protocols were designed to evaluate the voltage profile impact in a range relevant for both automotive and heavy duty transport application (<0.90 V). Besides the well-known aging dependence on the upper potential limit, this work evidences the critical role of the short-stops, characterized by low voltage transients. Effort was spent in studying this procedure parameters (voltage level, duration, scan rate, humidification). The accelerated ECSA loss is due to Pt nanoparticles coarsening as proved by transmission electron microscopy and is suspected dominated by Pt cathodic dissolution, incentivized during excursions towards very low potentials (<0.4 V). These findings help the development of system mitigation strategies. [Display omitted] • ASTs designed to test voltage profiles in automotive-representative conditions; • Voltage window and voltage transitions studied under hydrogen/air; • The critical role of the short-stops is attested; • The LPL is crucial for Pt oxides removal and nanoparticles coarsening even at <0.6V; • Tuning of the cathodic potential transient can be a valuable mitigation strategy. [ABSTRACT FROM AUTHOR]

Autothermal reactors can sustain the reactor operation without heat addition or removal. Catalyst is used in autothermal reactors to improve selectivity and minimize energy demand. The autothermal reactors can provide an energy-saving route for conducting chemical processes. The autothermal operation may reduce energy demands by 25%. The autothermal operation of the reactor is achieved by conducting heat transfer from an exothermic reaction mixture to an endothermic reaction mixture or by using a cold inlet to the reactor without an intermediate cooling/heating fluid. Catalytic autothermal reactors are used in several industrial applications. Academic and industrial researchers are working on developing innovative catalytic autothermal reactors for additional applications. The catalytic autothermal reactors are widely used in the Ammonia, automotive post-catalytic treatment, and syngas industries. Several pilot and lab-scale units were developed for hydrogen production, hydrocarbon reforming, and bioenergy applications. Several advanced catalytic autothermal systems were designed using recirculating, membrane, electrochemical, and micro-channel reactors. Catalytic autothermal reactors can be coupled with fuel cells to produce clean electricity using reforming products. This article examines autothermal reactor designs, catalysts, advanced methodologies, and economic considerations that position autothermal reactors as a compelling and innovative solution for reducing energy demand and achieving sustainable industrial practices. • Recent advances in autothermal reactors are reviewed. • Autothermal reactors represent an efficient solution for reducing energy demand and achieving sustainable industrial practices. • The reactor design and catalysts used are discussed in detail. • Innovative processes that employ autothermal reactors are reviewed. • Recommendations for future work that can further improve the feasibility of catalytic autothermal reactors are provided. [ABSTRACT FROM AUTHOR]

Catalytic formate decomposition under mild conditions is a promising strategy for hydrogen production as an efficient hydrogen carrier. Most of previous studies performed formate decomposition for hydrogen generation in liquid phase or using formate as a promoter for formic acid decomposition, which exhibits relatively low hydrogen energy density by mass. Here, we reported a gel-like formate system for catalytic hydrogen generation under mild conditions. A H 2 yield of 100% with hydrogen energy density by weight of 2.38 wt% was achieved, and the palladium catalyst shows high stability and recyclability for KCOOH gel decomposition. Moreover, the constructed gel-like formate filled in an aluminum cylinder could continuously and steadily supply hydrogen to a 12V/35W fuel cell to drive a LED display. This work may provide a new thought for safe hydrogen storage and production system for hydrogen energy usage in the future. • A gel-like KCOOH system was constructed for hydrogen generation under mild condition. • H 2 yield of 100% with hydrogen energy density by weight of 2.38 wt% was achieved. • The palladium catalyst shows high stability for decomposition of KCOOH gel. • The magnified KCOOH gel can be applied on a fuel cell system. [ABSTRACT FROM AUTHOR]

The recovery and utilization of oxygen in residential hydrogen energy storage systems significantly impact economic factors. This study introduces an algorithm tailored to optimize oxygen concentration (fraction) across varied operational conditions, encompassing considerations for both efficiency (positive aspect) and lifetime (negative aspect). Initially, an enhanced air supply system (ASS), functioning with oxygen-enriched cathode air, is devised following the forefront scheme. Moreover, a dynamic model is formulated based on MATLAB/Simulink® software for the proton exchange membrane fuel cell (PEMFC) system. The model enables quantitative assessment of system gains in relation to various current densities and oxygen fractions, and its accuracy is partially validated through experimental data. Further, a model correlating stack lifetime to oxygen concentration (fraction) is established using experimental data obtained from other researchers. Finally, the optimal oxygen fractions are determined and managed, with a comparison of the effects before and after optimization. The optimized results indicate a 13% improvement in stack net power at rated operating conditions and a 24% improvement at peak operating conditions, and the system efficiency is improved by 24% and 43% at rated and peak operating conditions, respectively. In addition, the minimum value of system efficiency is observed to be 54%, and there is a notable attenuation of the concentration polarization phenomenon. This approach contributes to mitigating the challenge of lower system efficiency in normal PEMFCs for residential hydrogen energy storage systems (RHESSs) attributed to inadequate gas supply pressure. • Oxygen utilization for residential hydrogen energy storage systems is considered. • An improved air supply system with oxygen-enriched cathode air is proposed. • An algorithm for optimizing oxygen concentration(fraction) is introduced. [ABSTRACT FROM AUTHOR]

This study presents the facile synthesis of CoO/PtPd and CoO/PtPd/reduced‐graphene oxide (r‐GO) nanocomposites, highlighting their significant role in methanol fuel cells. To create a CoO/PtPd thin film at the toluene/water interface, we employed NaBH4 to effectively reduce PtCl2(COD), PdCl2(COD), and Co (acac)3 (COD = cis,cis‐1,5‐ cyclooctadiene, acac = acetylacetonate). The two nanocomposites were analyzed using XRD, FE‐SEM, AFM, XPS, BET, and TEM techniques. In the electrooxidation of methanol in the anodic part of fuel cell, cobalt (II) oxide can serve as an oxygen source in the catalytic oxidation of carbon monoxide (CO) or it can play a role in producing the HO‐CoO intermediate to facilitate the oxidation of CO‐PtPd to carbon dioxide (CO2). This reaction can help eliminate CO, which is a common poison for Pt‐based catalysts in methanol oxidation. Our research reveals significant improvements in current densities and catalyst tolerance when using the CoO/PtPd/r‐GO nanocomposite thin film. The observed current density for CoO/PtPd/r‐GO is 263.33 mA.cm−2, surpassing the reported value of 30.00 mA.cm−2 for PtPd/r‐GO. The jf/jb ratios, commonly used to evaluate catalyst tolerance, are approximately 2.80 for CoO/PtPd and 4.98 for CoO/PtPd/r‐GO, in contrast to ratios larger than 0.99 for ETEK Pt and 0.58 for other types of commercial Pt/C. These findings indicate that the CoO/PtPd/r‐GO thin film exhibits enhanced catalytic performance and improved tolerance to CO poisoning. Furthermore, the power output calculated for CoO/PtPd/r‐GO is 104.5 mW·cm−2, which is comparable to the reported value of 48.03 mW·cm−2 for commercial Pt/C. These results demonstrate the potential of the CoO/PtPd/r‐GO nanocomposite thin film as a promising alternative to traditional catalyst materials in methanol fuel cells. [ABSTRACT FROM AUTHOR]

In this study, the most promising technology available, a fuel cell stack called a "Polymer-Electrolyte Membrane (PEMFC)," is used to power a brushless DC motor. To enhance the PEMFC's functionality, a robust "maximum power point tracking" (MPPT) algorithm was used in the DC/DC boost circuit. The "perturbation and observation" (P&O) method was developed for this purpose. In this paper, we present a self-tuning PI-fuzzy logic controller (FLC) for the speed of brushless DC (BLDC) motors. The effectiveness of the proposed controller was evaluated using simulated load disturbances and reference speed fluctuations. Hence, the rise time (R.T), settling time (S.T), steady-state error (S.S.E), overshoot (OVER), undershoot (UNDER), peak time (P.T), and peak value (P.V) are computed and examined as part of the required control performance characteristics. PEMFC source optimization with load variation and BLDC speed regulation is the key contribution of this study. The findings of this study have the potential to lead to the development of more efficient, sustainable energy systems that would be good for the planet and cheaper to operate. The results further demonstrate that the controller performs admirably across a wide range of speeds and loads since the PEMFC battery reliably supplies the power required for the BLDC motor. [ABSTRACT FROM AUTHOR]

Innovations in fuel cells bring important developments in obtaining energy. Especially with the anodic reactions of fuel cells and the catalysts used in the anodic part, it provides an increase in energy efficiency. With this study, modification of durable and high catalytic activity targeted carbon nanofibers (CNFs) with Platinum nanostructures (CNF@Pt) developed for alcohol oxidation was provided. Further, CNF@Pt was characterized by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD). According to Debye Scherrer, the crystalline particle size was approximately 2.27 nm, and the CNF diameter was measured as 161.57 nm according to the TEM results. Besides, the anodic reactions of methanol, ethanol, and 2-Propanol for direct alcohol fuel cells (DAFC) were investigated. Cyclic Voltammetry (CV), Chronoamperimetry (CA), and recycling performance tests were demonstrated in ideal operating rates of the catalyst. One of the highest anodic peak currents were measured as 145.43, 101.56, and 34.54 mA.cm− 2 for methanol, ethanol, and 2-propanol at a scanning speed of 50 mV/s, respectively. The CNF@Pt catalyst was also very stable and durable in stability tests. In this study, it has been seen that carbon-based fiber materials are an ideal catalyst to increase efficiency in fuel cells and to make sense of the results obtained in their use in different alcohol types. [ABSTRACT FROM AUTHOR]

Triple-conducting perovskites are the focus of extensive research and have emerged as high-performance cathode materials for proton-conducting solid oxide fuel cells (H–SOFCs). Notably, BaCe 0.36 Fe 0.64 O 3-δ (BCF36) has recently garnered attention for its ability to provide suitable oxygen ion conductivity and proton conductivity, all through skillful composition tuning. Here, A-site deficient BaCe 0.3 Fe 0.7 O 3-δ (D-BCF30) is prepared to further boost the cathode activity. The composition content is modified by introducing Ba cation deficiency according to XRD and calculation results. Remarkably, the single cell equipped with D-BCF30 cathode demonstrates a significantly enhancement in performance, featuring a high power density of 1425 mW cm−2 and a low polarization resistance of 0.045 Ω cm2 at 700 °C compared to stoichiometric BCF30. Moreover, the cell operation durability has markedly improved which is further substantiated through experiments and density functional theory (DFT) calculations, suggesting a promising avenue to improve performance and stability of H–SOFCs. [ABSTRACT FROM AUTHOR]

Carbon corrosion in a catalyst layer (CL) deteriorates the performance and durability of proton-exchange membrane fuel cells (PEMFCs), which are closely related to water management within these cells. This study investigates the characteristics of water behavior of two gas diffusion layers (GDLs) and compares their influence on degrees of degradation in the CL. First, the properties of the GDLs, including their thickness, pore size distribution, gas permeability, electrical resistance, contact angle, and polytetrafluoroethylene (PTFE) content, are evaluated. The dynamic behavior of liquid water is observed using a visualization cell and synchrotron X-ray imaging. Second, a modified accelerated stress test (AST), which includes a water generation reaction within the catalyst support protocol of the US Department of Energy (DOE), is performed. For assessing the degradation, we utilize polarization curves, electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, and field emission transmission electron microscopy. The results reveal that, even though GDL B contains a higher hydrophobic content than GDL A, it exhibits lower water discharge, indicating a reduced performance at high relative humidity (RH) levels. This is attributed to a low capillary pressure gradient, which is influenced not only by PTFE but also by the overall pore structure (i.e., porosity and pore size). Consequently, a high capillary pressure gradient can enhance water discharge and thereby mitigate carbon corrosion and Pt agglomeration in the CL. In addition, the application of the modified AST induces carbon corrosion with fewer cycles than that achieved using the DOE carbon support protocol. [ABSTRACT FROM AUTHOR]

The IrRh@C ZIF-8 catalysts capable of oxidizing H 2 , CO, or a combination of the two is fabricated through the secondary high temperature annealing. Benefiting from the closely located single atom sites to the nanoparticles, CO on the metal nanoparticles could be efficiently removed, thus conferring the catalysts with excellent H 2 oxidation performance in CO presence that has not been possible before. This work opens up a new avenue to conquer the formidable poisoning issue of PEMFCs. [Display omitted] Nanosized Pt catalysts are the catalyst-of-choice for proton exchange membrane fuel cell (PEMFC) anode, but are limited by their extreme sensitivity to CO in parts per million (ppm) level, thereby making the use of ultrapure H 2 a prerequisite to ensure acceptable performance. Herein, we confront the CO poisoning issue by bringing the Ir/Rh single atom sites to synergistically working with their metallic counterparts. In presence of 1000 ppm CO, the catalyst represents not only undisturbed H 2 oxidation reaction (HOR) catalytic behavior in electrochemical cell, but also unparalleled peak power density at 643 mW cm−2 in single cell, 27-fold in mass activity of the best PtRu/C catalysts available. Pre-poisoning experiments and surface-enhanced Raman scattering spectroscopy (SERS) and calculation results in combine suggest the presence of adjacent Ir/Rh single atom sites (SASs) to the nanoparticles (NPs) as the origin for this prominent catalytic behavior. The single sites not only exhibit superb CO oxidation performance by themselves, but can also scavenge the CO adsorbed on approximated NPs via supplying reactive OH* species. We open up a new route here to conquer the formidable CO poisoning issue through single atom and nanoparticle synergistic catalysis, and pave the way towards a more robust PEMFC future. [ABSTRACT FROM AUTHOR]

The sustainable chemical energy of H2O2 as a fuel and an oxidant in an advantageous single-compartment fuel cell design can be converted into electric energy, which requires molecular engineering to design suitable cathodes for lowering the high overpotential associated with H2O2 reduction. The present work covers the synthesis and structural characterization of a novel cathode material, [Fe III2 (hnmh-PLY)3] complex, 1, designed from a PLY-derived Schiff base ligand (E)-9-(2-((2-hydroxynaphthalen-1-yl)methylene)hydrazineyl)-1H-phenalen-1-one, hnmh-PLYH2. Complex 1, when coated on the surface of a glassy carbon electrode (GC-1) significantly catalyzed the reduction of H2O2 in an acidic medium. Therefore, a complex 1 modified glassy carbon electrode was employed in a one-compartment H2O2 fuel cell operated in 0.1 M HCl with Ni foam as the corresponding anode to produce a high open circuit potential (OCP) of 0.65 V and a peak power density (PPD) of 2.84 mW cm−2. CV studies of complex 1 revealed the crucial participation of two Fe(III) centers for initiating H2O2 reduction, and the role of coordinated redox-active PLY units is also highlighted. In the solid state, the π-conjugated network of coordinating (hnmh-PLY) ligands in complex 1 has manifested interesting face-to-face π–π stacking interactions, which have helped the reduction of the complex and facilitated the overall catalytic performance. [ABSTRACT FROM AUTHOR]

Pd and TiO2 supported on functionalized multiwall carbon nanotubes (f-MWCNTs) catalysts were investigated in formic acid electrooxidation reaction in direct formic acid fuel cell. TiO2 (5–60 wt.% loading) on f-MWCNTs was deposited using microwave-assisted hydrothermal method. 20 wt.% of Pd was deposited on TiO2/f-MWCNTs by reduction of palladium (II) chloride salt with sodium borohydride. Catalysts' structure and composition were characterized by XRD, STEM, HR-TEM, TGA, XPS/XAES (Pd, Ti, O spectra features, density of valence states, Auger parameters). Average crystallite size of Pd and TiO2 from XRD (3–4 nm) agrees with those by HR-TEM (3–5 nm). Low TiO2 coverages (below 32wt.%) show smaller crystallites due to increased surface hydrophilicity, higher amount of TiO2 oxygen vacancies with attached Pd nanoparticles, increased density of valence states of strong Pd–TiO2 interface. In contrary, the higher coverages indicate lower amount of Pd–O–Ti, Ti–O–C, Pd–O–C interfaces, with electron charge transfer from TiO2 to f-MWCNTs, and to Pd. Catalysts activity (40–106 mWmgPd−1) and stability (5–240 h) are enhanced at low TiO2 coverages (4–8 wt.%) due to a strong Pd-TiO2 interface on oxygen vacancies, improved electron transport and a high active surface area. Oscillatory self-cleaning mechanism of Pd is due to oxidation by -OH groups (TiO2, f-MWCNTs), and hydrogen and CO spillover. [ABSTRACT FROM AUTHOR]

Developing Fe-based high active and stable oxygen electrode materials is essential for commercializing solid oxide cells (SOC). Herein, La 0.5-x Bi x Sr 0.5 Fe 0.9 Mo 0.1 O 3-δ (x = 0–0.3) oxides are synthesized and used as oxygen electrodes for oxygen reduction/evolution reaction (ORR/OER). Bi-doping at La-site significantly improves the ORR/OER activity, producing high cell performance in fuel cell and electrolysis modes. At 800 °C, the polarization resistance of La 0.3 Bi 0.2 Sr 0.5 Fe 0.9 Mo 0.1 O 3-δ is only 0.09 Ω cm2, which is almost 3.5 times lower than undoped La 0.5 Sr 0.5 Fe 0.9 Mo 0.1 O 3-δ electrode. Moreover, the Ni-YSZ-supported full cell delivers a peak power density of 1237 mW cm−2 in fuel cell mode and a current density of −2717 mA cm−2 @ 1.5 V in electrolysis mode. The electrolysis cell demonstrates an excellent durable operation for ∼130 h under 500 mA cm−2 and 750 °C. Therefore, the Bi doping strategy is effective for designing highly active oxygen electrodes of solid oxide cells. [Display omitted] • Bi doping improves the ORR/OER activity of La 0.5-x Bi x Sr 0.5 Fe 0.9 Mo 0.1 O 3-δ oxyen electrode. • The R p of La 0.3 Bi 0.2 Sr 0.5 Fe 0.9 Mo 0.1 O 3-δ electrode is as low as 0.09 Ω cm2 at 800 °C. • High current density of −2.72 A cm−2 is obtained under 1.5 V and 50%H 2 O–H 2. [ABSTRACT FROM AUTHOR]

As the development of hydrogen fuel cell cars moves from concept to mass production, customers need safe, practical, and easy refueling experiences. The performance and lifetime of fuel cell stacks, as well as other operational factors like valve functioning, are greatly influenced by the purity of hydrogen. The advances achieved by earlier researchers in promoting hydrogen as a possible significant fuel source for the future are fully examined in this publication. Hydrogen is an energy carrier that has the potential to replace fossil fuels. It may be used as a fuel source for cars that run on fuel cells as well as internal combustion engines. To minimize aberrant combustion, extra consideration has to be given to engine design when considering hydrogen as a fuel for internal combustion engines. This strategy may result in higher power output, lower nitrogen oxide (NOx) emissions, and enhanced engine efficiency. The research explores the designs of fuel cell cars that use hydrogen by converting it into energy as well as the designs of internal combustion vehicles fueled by hydrogen via combustion. In addition, hybrid variants of these cars are shown for a thorough comprehension of the topic. The article also looks at the structure and future possible benefits of hydrogen fuel cell electric cars in the context of the automotive sector; these topics are covered in a separate section. [ABSTRACT FROM AUTHOR]

Schedule maintenance activities for hydrogen fuel cell vehicles are aimed to keep them in better condition in long-term operation. In this paper, we develop a reinforcement learning based schedule maintenance strategy, which is used to comprehensively consider the balance between safety and maintenance cost, so as to find the optimal maintenance strategy. A multi-level framework is established with remaining useful life of key components, fault tree analysis, and logistics cost model to generate an exploration environment that can express the operational stability, the failure rate of components, and the cost of repair and storage. The trained agent combines a deep neural network to explore the optimal strategy under the dynamic reliability of key components. Finite steps are the constraints. Safety rates, maintenance cost, and episode of operation are incorporated into a multi-objective reward function. The hydrogen supply circuit of fuel cell vehicle is simulated via Python. The trained agent is compared with traditional time-based schedule maintenance strategy and corrective maintenance strategy. The results show that the reinforcement learning based schedule maintenance agent has optimized the total reward, cost control and accident rate by 77%, 59% and 5%, respectively, compared with the traditional time-based schedule maintenance strategy. In the safe operation management of fuel cell vehicles, efficient and stable decision-making ability has been achieved. • An adaptive maintenance strategy of deep reinforcement learning is proposed. • An exploration environment of FCV is established. • The deep Q network is proposed to solve the maintenance problem. • The efficient and stable decision-making ability is much better than time-based scheduled maintenance strategy. [ABSTRACT FROM AUTHOR]

Proton-conducting solid oxide fuel cells (H-SOFCs) are appealing for low-to-intermediate temperature operation due to their intrinsic lower activation energy and better ionic conductivity. Unfortunately, there are currently few acceptable and high-performing cathode materials available for H-SOFCs. Herein, we present a novel high performance multicomponent Ruddlesden-Popper (RP) type cathode Pr 3 Ni 1.5 Cu 0.3 Nb 0.05 Ta 0.05 Zr 0.05 Y 0.05 O 7-δ (PNCNTZY) with superior triple conducting property. The multicomponent co-doping of Nb, Ta, Zr, and Y brings about the enhancement of configurational entropy and cocktail effect for improving H+/O2-/e- triple conductivity and oxygen vacancy concentration. Naturally, the ORR activity is improved by facilitated charge transfer and oxygen surface exchange, exhibiting reduced polarization resistance to just 0.24 Ω cm2 at 550 °C. When used as the cathode in H-SOFC single cells, excellent power production is demonstrated at 550 °C, with a peak power density of up to 0.84 W cm-2. Furthermore, the PNCNTZY sample shows adequate thermal compatibility with proton conductor electrolytes BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) and then appropriate endurance durability (0.8 A cm-2 at 550 °C for about 250 h) due to their match of thermal expansion coefficient (TEC) brought about by the Co-free and partial replacement of larger-size elements. This extremely promising Co-free RP perovskite cathode for H-SOFCs produced by this work might provide a new type candidate and novel strategy for the commercialization of H-SOFCs. [Display omitted] • Multicomponent Co-free Pr 3 Ni 1.5 Cu 0.3 Nb 0.05 Ta 0.05 Zr 0.05 Y 0.05 O 7-δ (PNCNTZY) was developed as H-SOFCs cathode. • PNCNTZY cathode has RP structure and triple-conductivity (H+/O2-/e-). • Multicomponent co-doping significantly improved ORR activity and triple conductivity. • Single cell with PNCNTZY cathode shows excellent peak power densities (0.84 W cm-2 at 550 °C) and durability. [ABSTRACT FROM AUTHOR]

The present article introduces an innovative solution to improve performance efficiency while shaving the demand during peak hours. The idea focuses on efficient gas turbine and Rankine cycle hybridization for power and hydrogen production based on high-temperature heliostat solar towers. The proposed model is simulated via TRNSYS software to assess the performance transiently and then optimized through the artificial neural network in MATLAB program to minimize the calculation time. The key economic, environmental, and energy indicators are evaluated, compared, and optimized for this. According to the effect of main design parameters, including gas turbine inlet temperature, mass flow rate, and heliostat area, on the system's indicators, there is a conflictive trend among the power productivity, cost, and emission index, signifying the optimization significance. The optimization results show that the net power, efficiency, cost, and CO 2 emissions are 298,300 GJ, 30.7%, 3.6 M$, and 20,760 tonnes under optimal conditions. This working condition is obtained by electing turbine inlet temperature, solar area, and airflow rate of 1087 °C, 91,200 m2, and 68,817, respectively. At this condition, while 71.18% of the yearly primary energy is provided by the sun, biomass meets the rest, showing the importance of renewable combination to achieve the highest independence from the grid. Finally, the system can generate an additional 585 kg/day of hydrogen that could be used in relevant industries. • A novel smart system based on biomass and solar hybridization is introduced. • A new hydrogen production/injection method is applied to improve the efficiency. • An artificial neural network model is added to the optimization to reduce the time. • The proposed smart system can generate an extra hydrogen of 585 kg per day. • The optimization achieves an efficiency of 30.7% and emissions of 20,760 tonnes. [ABSTRACT FROM AUTHOR]

A viable alternative to non‐renewable hydrocarbon fuels is hydrogen gas, created using a safe, environmentally friendly process like water splitting. An important role in water‐splitting applications is played by the development of two‐dimensional (2D) layered transition metal chalcogenides (TMDCs), transition metal carbides (MXenes), graphene‐derived 2D layered nanomaterials, phosphorene, and hexagonal boron nitride. Advanced synthesis methods and characterization instruments enabled an effective application for improved electrocatalytic water splitting and sustainable hydrogen production. Enhancing active sites, modifying the phase and electronic structure, adding conductive elements like transition metals, forming heterostructures, altering the defect state, etc., can improve the catalytic activity of 2D stacked hybrid monolayer nanomaterials. The majority of global research and development is focused on finding safer substitutes for petrochemical fuels, and this review summarizes recent advancements in the field of 2D monolayer nanomaterials in water splitting for industrial‐scale green hydrogen production and fuel cell applications. [ABSTRACT FROM AUTHOR]

Lignocellulose flow fuel cells are promising technologies for large scale generation of renewable electricity at low temperature. However, most of them have low electron transfer kinetics and require pre-reaction and redox mediators in anolytes for a liquid-phase catalytic reaction, which leads to low power density, energy consumption and resource waste. Herein, we develop a new low temperature and high-power density lignin flow fuel cell (LFFC) catalyzed by CoMn-LDH electrocatalysts with superhydrophilic intercalation on the anode to efficiently degrade lignin and transfer electrons rapidly. The experiments and DFT calculations show that CoMn-LDH exhibits high adsorption capacity for lignin due to its superhydrophilic intercalation, and has good electrical conductivity due to the greater overlap of antibonding orbitals and high continuity at the Fermi level. Moreover, the abundant oxygen defects of CoMn-LDH can depolymerize lignin effectively. Thus, the prepared CoMn-LDH electrocatalyst enables fast charge transfer and high catalytic efficiency. The power density of the designed LFFC reached 269.3 mW cm−2, and the generated electrical energy is 294.7 mW h based on 1.0 g of lignin, which are obviously higher than those of the reported LFFCs. Furthermore, it can work stably for more than 9 h at 0.3 V and 413.5 mA cm−2, and successfully power a 1.5 V LED pattern with only a 1 cm2 active membrane. It presents a promising approach for developing high-power density LFFCs towards a sustainable society. [ABSTRACT FROM AUTHOR]

We introduce a straightforward, yet effective strategy to combat the performance decline of proton-exchange membrane fuel cells in low-humidity environments. Our method centers on air-oxidizing carbon supports, significantly improving proton and oxygen transport within the cathode catalyst layer. [ABSTRACT FROM AUTHOR]

Designing an electrocatalyst with low Pt content is an immediate need for essential reactions in low temperature fuel cell systems. In the present work, La0.9925Ba0.0075Al0.995Pt0.005O3 is aimed at using with low (only 0.5%) Pt doping as an electrocatalyst for oxygen reduction reaction (ORR). The low doping level renders exsolution of 1–2 nm nanoparticles with uniform dispersion upon reduction in H2/N2 at low temperatures. Pt exsolved perovskite oxides deliver significantly enhanced catalytic activity for ORR and improved stability in alkaline media. This study demonstrates that LaAlO3 with low noble metal content holds immense potential as an electrocatalyst in real fuel cell systems. [ABSTRACT FROM AUTHOR]

This work proposes an original method for tailoring the microstructure and electrical properties of Ni/GDC anodes by using 3D inkjet printing of high-viscosity functional compositions with intermediate laser treatment of each layer after each printing pass. Based on a mixture of highly dispersed oxides NiO and CeO 2 doped with gadolinium (GDC), paste formulations for 3D inkjet printing have been developed. The effects of 3D printing and laser treatment conditions on the porosity and shrinkage ratio of the NiO/GDC anodes during sintering were investigated. The reduction of the anode support workpieces to produce Ni/GDC cermet was carried out and the effect of laser exposure on the morphology and electrical characteristics of the resulting samples was studied. It was found that an increase in the laser exposure values during layer-by-layer laser treatment of printing compositions leads to a two-fold increase in the porosity of the solid oxide fuel cell components, an increase in the average pore size from 0.2 to 0.3 to 2–5 μm, and to a five-fold decrease in the sintering shrinkage ratio. It was also found that the electrical conductivity of the Ni/GDC cermet, produced by the reduction of the laser treated NiO/GDC, increased by 5–10 times as the laser exposure values increased. The influence mechanism of the layer-by-layer laser treatment of the original NiO/GDC samples on the electrical conductivity of their reduced counterparts, Ni/GDC cermet anodes, has been proposed. An increase in the electrical conductivity was shown to be due to in situ reduction of NiO, partial sintering of Ni nanoparticles and the formation of a percolation network. This new method of hybrid 3D printing opens up great prospects for tailoring the morphological and electrical characteristics of SOFC anode supports. [ABSTRACT FROM AUTHOR]