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In this study, the microstructure of carbon fiber paper is modified through H 3 PO 4 etching to enhance the electrolyzer performance. The effects of different H 3 PO 4 concentrations and different soaking times on the hydrogen evolution reaction are firstly investigated. The electrochemical test results show that the best performance of etched electrodes is achieved at a H 3 PO 4 concentration of 1 M and a soaking time of 12 h, with a significant reduction in charge transfer resistance and overpotential. Subsequently, to explore the change mechanism in electrochemical properties, the microstructure of the carbon paper is investigated using Scanning Electron Microscope (SEM) and Mercury Intrusion Porosimetry (MIP) tests, which show uniformly distributed micropores appear on the surface of the carbon fibers after etching, and the porosity increases from 0.74 to 0.8. Brunauer-Emmett-Teller (BET) tests show that the specific surface area of the carbon paper increases from 0.72 m2/g to 4.06 m2/g, which effectively increases the interfacial contact area between the catalyst layer and the liquid gas diffusion layer. Furthermore, a 3D multi-physics model is established to further elucidate the impact mechanism of changes in porosity, conductivity, and active specific surface area on the performance of anion exchange membrane electrolyzer, with changes in active specific surface area having the greatest effect. • Microporous structure of the carbon paper LGDL is modified by etching. • The etching method effectively improves the performance of AEMEL. • The increase in specific surface area and porosity greatly reduces the resistance. • Numerical modeling to analyze the impact of microscopic parameters on AEMEL. • LGDL with high specific surface area has a positive effect on AEMEL's development. [ABSTRACT FROM AUTHOR]

Carbon fiber paper (CFP) is one of the most widely used gas diffusion layer materials for proton exchange membrane fuel cells (PEMFC) due to its excellent properties such as high conductivity, high strength, high air permeability and corrosion resistance. In this study, CFP was prepared using the phenolic resin (PF) in-pulp addition method. The effect of PF content on the properties of hot-pressed paper (HPP) and CFP was investigated. The results showed that when the dosage of polyethylene oxide (PEO) was 1.5 wt%, the flocculation effect of PEO on PF was basically complete, and the water filterability and retention of carbon fiber pulp were relatively optimal. After HPP was carbonized into CFP, the hydrophobicity, average pore size, porosity, and air permeability increased, while the resistivity and tensile strength decreased. With the increase of PF content, the tensile strength of CFP gradually increased, while the average pore size, porosity, air permeability and resistivity decreased. When the PF content was 250 wt%, the average pore size of CFP was 36.5 μm, the water contact angle was 127°, the porosity was 69.7%, the air permeability was 7.81 × 103 mL mm/(cm2·h·mmHg), the resistivity was 21.1 mΩ cm, and the tensile strength was 15.7 MPa. In addition, the CFP prepared using PF in-pulp addition method had a relativity uniform pore size distribution and high air permeability. Therefore, this work shows that the CFP prepared using this technique exhibits excellent comprehensive performance, and enables the manufacturing of CFP to be more efficient, low-cost, and environmentally friendly. [Display omitted] • Carbon fiber paper was prepared efficiently using the phenolic resin in-pulp addition method. • Polyethylene oxide exhibits strong adsorption ability on phenolic resin in carbon fiber pulp. • The melting temperature of phenolic resin is a critical point in the preparation process of carbon fiber paper. • Carbon fiber paper possesses a relatively uniform pore size distribution and high air permeability. [ABSTRACT FROM AUTHOR]

Carbon paper as a macroporous substrate of gas diffusion layer in proton exchange membrane fuel cells directly impacts the output performance of cells. In this study, we present a straightforward strategy to improve the overall performance of carbon paper by mixing short/long (6mm/10 mm) chopped carbon fibers at an optimal concentration of phenolic resin. The results show that incorporating longer carbon fibers can increase the porosity, conductivity, gas flux, and mechanical properties of carbon paper. The membrane electrode assembly achieved a peak power density of 1182.61 mW cm−2 at 60% RH using carbon paper with a long carbon fiber content of 40 wt% and an impregnation concentration of 10 wt%. This outperforms commercially available carbon paper. Based on electrochemical impedance spectroscopy results, it was confirmed that our carbon paper had a lower mass transfer resistance of only 32.17 mΩ cm−2 under conditions of 2 A cm−2 and 60% RH. This was due to its sparser three−dimensional network-like pore structure which was created by mixing different lengths (6mm/10 mm) of carbon fibers. This work provides new insights into preparing high−performance carbon papers. • The nature of carbon paper is regulated by mixing short/long (6mm/10 mm) CFs ratio. • The long carbon fiber contents of 20–40 wt% present better physical properties. • The optimal carbon papers can mitigate mass transfer resistance. • MEA composed of the optimal CP shows a higher power density than commercial CP. [ABSTRACT FROM AUTHOR]

A facile method is proposed in this work to prepare a carbon paper (CP) with outstanding properties by doping boron to catalyze graphitization at lower temperature. Boron was introduced into CP by impregnating carbon fiber preform into a boron/phenolic resin/ethanol solution, and then CP was obtained after the consecutive procedures of hot pressing, carbonization, and graphitization. Morphology, microstructure, composition, and physical properties of the doped and undoped CPs were thoroughly investigated via various techniques to exam the effects of boron concentration and graphitization temperature. Furthermore, the boron doped CP was fabricated into fuel cell gas diffusion layer (GDL) and membrane electrode assembly (MEA) to evaluate its performance through the single cell performance. The findings indicated CP doping with 2 wt% boron could lower the graphitization temperature by at least 200 °C. The B-doped GDL had a higher power density in comparison with the undoped GDLs made in our lab or from the commercial brands. • The innovative preparation method for carbon paper with high conductivity. • The effect of boron concentration and graphitization temperature on carbon paper. • The single cell performance of B-doped gas diffusion layer. [ABSTRACT FROM AUTHOR]

Development of low-cost, efficient, and stable oxygen evolution electrocatalysts is crucial for the conversion and storage of renewable energy. Therefore, an effective integrated heterostructure catalyst is needed to achieve a lower overpotential during oxygen evolution process. In this paper, cobalt-zinc bimetallic MOF precursors are used as templates to prepare bimetallic cobalt-based selenides with good oxygen evolution catalytic activity and stability on carbon fiber paper. Due to the high specific surface area and porous structure of the coupling structure of nanorods and polyhedra, and the strong electronic coupling between CoSe 2 and ZnSe on nanorods. CoSe 2 -ZnSe/CP exhibits excellent electrocatalytic activity in 1 M KOH solution. It only requires an overpotential of 275 mV to reach the current density of 10 mA cm-2, and the Tafel slope is 68.9 mV dec-1. In addition, after 12 h of continuous operation of CoSe 2 -ZnSe/CP, the activity decay of the catalyst is negligible. This work provides a method for the design of heterogeneous bimetallic selenide integrated oxygen evolution electrocatalysts. [Display omitted] • The CoSe 2 -ZnSe/CP catalyst is obtained by selenization of MOF precursor at high temperature. • The catalyst has unique nanorod-coupled polyhedral morphology and high specific surface area. • The strong electron coupling between CoSe 2 and ZnSe improves the oxygen evolution activity. • CoSe 2 -ZnSe/CP exhibits low overpotential, high exchange current density and fast kinetics. [ABSTRACT FROM AUTHOR]

The solar photocatalytic degradation of pulp and paper mill wastewater has been reported by several scientists. However, this is the first time we are reporting for solar photocatalytic hydrogen production from pulp and paper mill wastewater and simultaneous degradation of pollutants. In this work, CuO based photocatalysts and novel square type photocatalytic reactor of 5 L capacity were used. The result shows that the prepared photocatalysts are solar active, efficient in hydrogen recovery and pollutant degradation from the pulp and paper wastewater. The effects of catalyst loading, sacrificial agent, pollutant removal efficiency and stability check were investigated. At 0.25 g/L of CuO/Fe 2 O 3 , 0.2 M of sacrificial agent (Na 2 SO 3 2−) and hydrogen yield of 1000 mL from 1000 mL of wastewater was achieved. The removal efficiency of TSS, TDS, BOD, COD, turbidity and TOC are around 70, 50, 60, 65, 70 and 45% respectively. Reusability study revealed that CuO/Fe 2 O 3 was chemically stable and could be reused successively (five cycles) without significant changes in its photoactivity and intrinsic properties. [Display omitted] • Visible light active CuO mixed with novel metal oxides were employed. • Hydrogen recovery from black liquor, paper mill wastewater were 1000 mL/h/L and 850 mL/h/L. • Efficiency of degradation of pulp & paper wastewater chemicals were around 50–70%. • AcHieved high recovery of hydrogen from pulp & paper wastewater. [ABSTRACT FROM AUTHOR]

The Proton Exchange Membrane Fuel Cell (PEMFC) performances are strongly impacted by the compression of the Gas Diffusion Layer (GDL). Despite its fibrous microstructure, this material is usually considered as a continuous medium and characterized with uniform loading. However, the GDL is subjected to a heterogeneous compression onto rib/channel patterns in the fuel cell assembly. In the present study, a complex behavior of the GDL response is experimentally revealed when the material is loaded with a rib/channel pattern, compared to uniform compression. The tests are simulated by finite element modeling using a classical strain-dependent elastic law, using parameters fitted from uniform compression experiments. It is shown that the numerical results do not reproduce the effect of pattern observed experimentally. Hypotheses to interpret these results involve mechanisms at the fiber microscale including fiber fracture, cross-link breakage and fiber rearrangement, which are exacerbated by larger material deformation caused by the heterogeneous loading. • Unexpected impact of rib/channel patterns on GDL compression. • Experimental investigation of the effect of rib/channel width on GDL deformation. • Numerical study with classical model unable to reproduce experimental results. • Interpretations based on mechanisms at the fiber microscale. [ABSTRACT FROM AUTHOR]

The large-scale development of flexible electrode is urgently needed for water electrosplitting. Herein, the common and low-cost filter paper (FP) is utilized as the substrate to adjust the flexible property of the catalytic electrode. Through an electroless plating method, the NiFeP alloys were deposited onto the filter paper, which acted as the flexible and self-supported electrode for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The resultant NiFeP@FPs require low overpotentials of 158 mV for HER and 282 mV for OER to deliver a current density of 10 mA cm−2, and exhibit a good stability of 30 h in 1 M KOH. The synergistic effect of Fe–Ni sites regulates electron structure and boosts the catalytic activity. Benefited from good hydrophilicity and interlaced fiber structure of filter paper, electrolyte penetration and electron transfer in the sample are promoted. The assembled two-electrode electrolyzer only requires 1.814 V to achieve 100 mA cm−2 for overall water splitting and shows excellent stability. This work provides a new strategy for the development of flexible and efficient electrodes for water splitting, which advances the development of wearable electronic devices. [Display omitted] • The flexible filter paper-based electrode was successfully synthesized. • The good hydrophilicity and porous structure facilitated electrolyte permeation. • The sample required low overpotentials of 158 mV for HER and 282 mV for OER. • The two-electrode electrolyzer provided 100 mA cm−2 at a low voltage of 1.814 V. [ABSTRACT FROM AUTHOR]

Black liquor (BL) bioconversion into valuable by-products is essential to develop a bioeconomy strategy; however, its furfural content hinders microbial fermentation activities. Hence, this study utilizes paper mill sludge (PMS) to provide extracellular enzymes, furfural-degrading microbial consortia, and electron donor required for promoting the BL hydrogenesis potential. Three up-flow anaerobic sequential batch reactors (UASBRs) are fed with PMS (UASBR1), BL (UASBR2), and PMS + BL (UASBR3) and operated in parallel at 15 min fill, 72 h reaction, and 4 h settling. The UASBR3 achieves the maximum volumetric H 2 of 1.483 ± 0.088 L/L/d and H 2 yield of 2.06 ± 0.12 mol/mol glucose, which drops by 88% in UASBR2 and 24% in UASBR1. The insufficient H 2 productivity values in UASBR2 could be due to a lack of nutrients availability (C:N = 440:1 and C:P = 19:1), higher furfural concentration (2116 ± 422 mg/L), and involvement of the butyrate fermentation pathway. The synergetic effect between PMS and BL overcomes these limitations and enriches the fermentation medium with Proteobacteria phyla (22.8%) and Acinetobacter sp. degrading furfural (6.1%). The microbial community at the phylum level (e.g., Proteobacteria , Firmicutes , and Actinobacteria) in UASBR3 maximizes the migration of electrons (e−eq = 9.34 ± 0.54%) towards efficient H 2 formation. [Display omitted] • Paper mill sludge (PMS) mitigated inhibitory effect of furfural in black liquor (BL). • PMS improved H 2 yield from the BL by 8.3-folds and accounted for 2.1 mol/mol glucose. • e– eq transferred to H 2 was 9.3% in the PMS:BL, 7.4% in PMS, and 1.27% in BL. • Acinetobacter degrading furfural (6.1%) was abundant with PMS addition. • Bacilli (8.9%) and Clostridia (5.4%) was dominant in the hydrogenesis of PMS:BL. [ABSTRACT FROM AUTHOR]

This research investigated the hydrogen production and energy conversion from automobile shredder residues (ASRs) and paper mill sludge (PMS) co-gasified in a full-scale fluidized bed gasification plant. The results obtained from full-scale tests provided important information on the feasible assessment of ASRs-to-energy and the selection of alternative technologies for ASRs. Based on the analysis results of produced gas composition, H 2 , CO, and CH 4 composition produced from paper-mill sludge gasified were 4.17%–6.01%, 3.08%–4.32%, 1.71%–2.4%, respectively. Another C 2 gas composition ranged from 2.9% to 3.59%. The heating value of produced gas ranged between 1.64 MJ/Nm3 and 2.18 MJ/Nm3. In the case of 10% ASR addition, the heating value of produced gas was slightly increased to 1.84 MJ/Nm3-2.34 MJ/Nm3. The dioxin emission concentration of flue gas was approximately 0.064 ng I-TEQ/Nm3. It can comply with Taiwan regulation thresholds. The dioxin leaching concentrations of residues derived from gasification were also in compliance with regulation limits by the TCLP test. Meanwhile, in the case of 10% ASRs addition, the dioxin equivalence concentration of gasified residue was nearly 0.002 ng I-TEQ/Nm3. It was far below the current regulation standard limit. In summary, the results of this research have proved the performance of ASRs-to-energy by co-gasified with paper mill sludge using a full-scale gasification plant. The results obtained from this research also provided the information for selecting ASRs alternative technologies and operating full-scale gasifiers in the future. [Display omitted] • This study has confirmed the feasibility of co-gasification of calcium-rich PMS and chlorine-rich ASRs. • Adding 5%–15% of ASRs can maintain the regular operation of the full-scale commercial gasifier. • The synthesis gas has a composition of 4.91 vol% H 2 and 2.06 vol% CO, with a LHV of 1.93 MJ/Nm3. • The HCl emission could comply with regulation thresholds in co-gasification. • Dioxin reformation reduced significantly in co-gasification of PMS and ASRs. [ABSTRACT FROM AUTHOR]

In this study, practical application for the industrial-scale hydrogen evolution reaction (HER) process is established using sustainable Cu 2 CoSnS 4 embedded in paper-working electrodes. The Cu 2 CoSnS 4 is produced using a solvent-free solid-phase approach. The effect of a wide pH range of electrolytes on working electrodes for hydrogen evolution reactions is also investigated. The Cu 2 CoSnS 4 embedded paper-working electrodes exhibit goodelectrocatalytic activity for hydrogen evolution reaction with low overpotential values of 233, 310, and 261 mV vs RHE at 10 mA/cm 2 in 0.5 M H 2 SO 4 ,1 M KOH, and 1 M PBS, respectively. These designed electrodes exhibit high double-layer capacitance and electrochemical surface area for a wide pH range. In acidic, alkaline and neutral environments, the catalyst-embedded paper electrodes explicit high turnover frequencies of 2.15 s−1, 2.75 s−1, and 2.11 s−1, respectively. The temperature-dependent hydrogen evolution reaction is studied to calculate the activation energy of the cathodic electrode. Utilising chrono-amperometry for about 118 h in an acidic media, which shows that electrodes have a high degree of stability. In comparison to other previously reported work on catalyst-embedded electrodes, the Cu 2 CoSnS 4 embedded paper-working electrodes offer excellentpotential for HER activity across a wide pH range and are suitable for industrial application. • Cu 2 CoSnS 4 embedded paper working electrodes are developed for hydrogen generation. • The electrodes exhibit universal pH hydrogen evolution reaction. • Electrodes shows excellent stability upto 40hr for continuous hydrogen generation. • The electrode displays good stability at current density more than 200 mA/cm2. [ABSTRACT FROM AUTHOR]

Active and stable electrocatalysts with low precious metal loading is essential for the widespread application of proton-exchange water electrolyzers. Construction of core-shell structure offers the possibility to achieve high catalytic activity and good stability, and simultaneously to reduce the precious-metal loading. Here, Co 3 O 4 -core IrO x -shell nanoparticles (Co 3 O 4 @IrO x) are synthesized by immersing the solvothermal synthesized Co 3 O 4 in alkaline IrCl 3 aqueous solution, followed by annealing at 350 °C for 2 h. The Co 3 O 4 @IrO x -10, which exhibits the highest oxygen evolution reaction (OER) activity when supported on carbon paper, are 9.76 nm in average diameter, and the surface IrO x layer is about 0.97 nm. Only 337 mV overpotentials are required to reach the 10 mA cm−2 OER current densities in 0.1 M HClO 4 for the Co 3 O 4 @IrO x -10, with the mass activity reaches 1.44 A mg−1 Ir at 370 mV overpotentials. The high OER activity is originated from the increased number of active sites and more facile kinetics, demonstrated by the lower charge transfer resistance, lower activation energy and lower Tafel slope values. The optimized adsorption energy of OH* intermediates caused by the electronic interaction between the Co 3 O 4 core and the IrO x shell facilitates the OER kinetics. The Co 3 O 4 @IrO x -10 supported on carbon paper is stable towards the long-term OER in acid, and the IrO x shell layer can effectively protect the Co 3 O 4 core. The Co 3 O 4 @IrO x -10 are promising candidates as the low precious metal electrocatalysts for OER in acid. • The Co 3 O 4 @IrO x -y core-shell nanoparticles are synthesized successfully. • The core-shell structure enhanced the activity and stability of the catalyst. • The core-shell structure significantly reduced the amount of IrO x addition. • The electron interaction between Co 3 O 4 and IrO x optimizes the adsorption energy of OH* intermediates. [ABSTRACT FROM AUTHOR]

The plasma treatment method, which is a simple and ecologically benign procedure, is used to treat the gas diffusion layer (GDL) surface for proton exchange membrane fuel cell (PEMFC) application. The surface plasma treatment greatly aids in the uniform in situ growth of platinum (Pt) nanowires on the GDL surface to fabricate gas diffusion electrodes (GDEs). Helium (He) and nitrogen (N 2) are used, and the outcomes from utilising each gas independently are compared at four different durations between 30 s, 60 s, 90 s, and 120 s. Membrane Electrode Assemblies (MEAs) are fabricated with the as-prepared GDEs and tested in H 2 /air PEMFC single cells. The testing results show the nitrogen plasma applied to the GDE surface for 60 s produces the best power performance with a current density of 1372.7 mA/cm2 at 0.6V. [Display omitted] • The surface of the gas diffusion layer (GDL) was activated using the plasma treatment method. • Carbon papers, whose surface was activated by He and N2 in plasma, were immersed in the prepared Pt solution. • Pt nanowires were allowed to grow on carbon papers. • Membrane Electrode Assemblies (MEAs) were created using as-prepared GDEs as the cathode and purchased GDL as the anode. • As a result of testing the created MEAs, it was seen that the GDL surface activated using N 2 plasma gave better results. [ABSTRACT FROM AUTHOR]

Molybdenum sulphide (2D-MoS 2) promises great potential as a hydrogen evolution (HER) catalyst, especially, when combined with conductive carbon supports like graphene oxide (GO) and carbon nanotubes (CNT). However, the hydrophobic nature of these carbon supports limits the catalytic potential of MoS 2. To overcome this, we introduced hydrophilic Nickel Boride (Ni 2 B) into GO/CNT electrodes (Ni 2 B-GO/CNT), enhancing wettability (Contact angle-25.3°) and HER activity. By hydrothermally depositing MoS 2 onto the hydrophilic Ni 2 B-GO/CNT electrode, we fabricated a self-supporting MoS 2 @Ni 2 B-GO/CNT electrode. The MoS 2 deposition led to the formation of MoS 2 @Ni 2 B-GO/CNT heterostructure with multiple interfaces, favoring interfacial electronic redistribution (XPS) to significantly improve the HER activity. Thus, the proposed MoS 2 @Ni 2 B-GO/CNT electrode exhibited an excellent durability of 100 h (97%) and an overpotential of 224 mV at 10 mA cm−2 in acidic medium. [Display omitted] • Hydrothermal growth of MoS 2 on Ni 2 B-GO/CNT to form a self-supporting electrode. • Hydrophilic Ni 2 B was incorporated into the GO/CNT matrix to enhance electrode wettability. • Enhanced HER catalytic activity from a heterostructure of MoS 2 with Ni 2 B, GO and CNT. • Excellent durability of MoS 2 @ Ni 2 B-GO/CNT was achieved for 100 h in acidic medium. [ABSTRACT FROM AUTHOR]

The surface properties of the anode porous transport layer (PTL) significantly impact the performance of a proton exchange membrane water electrolyzer (PEMWE). The pretreatment (ultrasonic cleaning and acid etching) of a pristine titanium (Ti) felt before it is used as the anode PTL and the surface structural modification of a PTL are two critical methods to improve the performance of an electrolyzer. However, the mechanisms for the pretreatment and surface modification need to be clarified. In this paper, five electrolyzers with five different-fabricated-ways anode PTLs are tested and compared based on I–V curves, EIS curves, and physical characterization techniques. X-ray photoelectron spectroscopy (XPS) results show that the ultrasonic cleaning pretreatment of PTL can improve hydrophilicity by increasing the amount of hydroxyl. In addition, EIS results indicate the significant charge transfer resistance of electrolyzer taking pristine titanium felt as PTL. Adopting the carbon paper as a microporous layer (MPL) or treated titanium felt with acid etching can eliminate or reduce the charge transfer resistance of the electrolyzer. Finally, the mechanism of surface pretreatment and modification of PTL are disclosed to cast light on the improvement of PTLs in further study. • Mechanisms of pretreatments and surface modifications for PTLs are investigated. • Electrolyzers with different-fabricated-ways anode PTLs are tested and compared. • Ultrasonic cleaning strengthens the hydrophilicity of the PTL. • Supplementing MPL or acid pretreatments can improve the anode charge transfer. • Improved mass and electron transport are the reasons for the improved performance. [ABSTRACT FROM AUTHOR]

The development of effective and inexpensive electrocatalysts for hydrogen evolution reaction (HER) plays a key role in future energy system. Herein, we report a series of NiS x composited with polypyrrole (PPy) hollow nanospheres on carbon papers (CPs) to promote the HER performance. The crystal phase and lattice configuration of the in-situ grown NiS x can be tuned through unipolar pulse electrodeposition. The PPy with high conductivity is conducive to prevent the NiS x from collapse and improve the stability of the HER. As a result, the optimized Ni 3 S 2 /PPy/CP electrode manifests a low overpotential of 149 mV (vs. RHE) at 10 mA cm−2, an exceptional long-term stability over 100 h, and a large electrochemically active surface area of 1173.75 cm2. Furthermore, it is found that the exposure of (110), (122) and (300) planes of Ni 3 S 2 facilitates to increase the number of active sites. The precise lattice regulation contributes to achieve high HER performance. [Display omitted] • A series of NiS x /PPy/CP composite electrocatalysts were prepared for HER. • The crystalline phase of NiS x can be tuned by controlling the lattice structure. • The (110), (122) and (300) lattice planes of Ni 3 S 2 provide rich active sites for HER. • The optimal Ni 3 S 2 /PPy/CP showed a low overpotential of 149 mV at 10 mA cm−2. • PPy is able to protect active substance from loss and improve long-term stability. [ABSTRACT FROM AUTHOR]

Currently, developing highly active and low-cost electrocatalytic materials for oxygen evolution reaction (OER) is an enormously grand challenge. Herein, we developed a novel and highly active Mn doped Co 2 Fe layer double hydroxide (LDH) electrocatalyst for OER. We discovered that these electrocatalytic materials can be directly grown on carbon papers to construct high-specific-surface-area electrode, which shows the lowest overpotential of 266 mV at 10 mA cm−2. Furthermore, after introducing Mn element, DFT + U calculation found that the ∗OOH of Fe-site on Co 2 Fe 0.67 Mn 0.33 LDH could draw more electrons than Co 2 Fe LDH due to the electronegativity differences between Fe-site on Co 2 Fe 0.67 Mn 0.33 LDH and Fe-site on Co 2 Fe LDH, which is reason that the energy level of Fe 3d (e g) was obviously downshifted by d-d repulsion of Mn 3d and Fe 3d in the neighboring sites of Co 2 Fe 0.67 Mn 0.33 LDH after doped Mn element, which leads to reduce charge-transfer energy from O 2p to Fe 3d (e g) to promote oxygen evolution processes for OER. Meanwhile, the band gap is also decreased after doped Mn element in Co 2 Fe LDH due to the downshifted e g orbital energy of Fe 3d. This study gives a general avenue to design and developing efficiently active LDH electrocatalysts for OER in the future. • Both bimetallic CoFe LDH and Mn doped CoFe LDHs directly grown on carbon paper are successfully synthesized. • The Co 2 Fe 0.67 Mn 0.33 LDH@NFs exhibits a small overpotential of 236 mV at 10 mA cm−1 for OER. • DFT + U studies reveal that the observed superb OER activity could be attributed to d-d repulsion of Mn 3d and Fe 3d. [ABSTRACT FROM AUTHOR]

One of the biggest challenges to the sustainable manufacture of liquid ammonia and the prevention of worldwide water contamination is the development of effective electrocatalysts for the electrochemical reduction of nitrate (NO 3 −) to NH 3 with high stability. Herein, a highly active and serviceable electrocatalyst is synthesized by pyrolysis, composed of nanostructure nickel phosphide (Ni 2 P) embedded in nitrogen phosphide doped carbon (NPC) followed by deposition on carbon paper (CP) to improve the electrocatalytic nitrate reduction. Various characterization techniques investigate the crystallinity, morphology, and chemical components of the Ni 2 P-NPC/CP nanoparticles. The results support the formation of nanostructure Ni 2 P and strong synergistic interactions between Ni 2 P and NPC, which resulted in substantial active sites and high electrical conductivity. Excellent performance of Ni 2 P-NPC/CP nanoparticles is achieved for electrocatalytic NO 3 − reduction with an NH 4 + yield rate of 2.468 mg h−1 mg cat. −1 and Faradaic efficiency (FE) of 84.6% at −1.2 V vs. RHE. Additionally, Ni 2 P-NPC/CP nanoparticles exhibit exceptional robustness and endurance. Studies using isotope labeling have been carried out, and the results show that nitrate reduction produces ammonia. Ni 2 P-based electrocatalysts can effectively treat nitrate wastewater to recover ammonia and facilitate its use in diverse industrial applications. • Ni 2 P-NPC/CP offers a highly active and durable electrocatalyst for the conversion of nitrate to ammonia. • Ni 2 P-NPC/CP achieved NH 4 + yield rate of 2.468 mmol h−1 mgcat−1 and Faradaic efficiency of 84.6% at −1.2 V. • The unique Ni 2 P-NPC/CP ensures robustness and practical options for continuous nitrate reduction processes. • Ni 2 P-NPC/CP offers a carbon-free energy solution through the selective conversion of nitrate to NH 3. [ABSTRACT FROM AUTHOR]

Hydrogen fuel is a non-toxic and source-abundant energetic system, but for its applications in the industry, several issues related to its storage must be resolved. Compounds like NaBH 4 appear as promising hydrogen sources, while can release the latter rapidly under controllable conditions with the use of heterogeneous catalyst systems. In this work, we synthesized a Ni–CoP catalyst by electrodeposition in a three-step process on carbon paper as support. The materials were characterized via SEM-EDS, XRD, and XPS techniques, while the hydrogen evolution reaction (HER) from alkaline NaBH 4 solutions was tested as a batch experiment. Ni–CoP catalyst showed a high amount of H 2 generated in a short time (∼550 mL in 1 min) and remained at 78 and 54% of its initial performance after respectively 100 and 300 h of a continuous hydrolysis process. Our catalyst revealed exceptional performance and stability at higher temperatures and a long process time, which have been a rare subject of investigation in other reports for NaBH 4 hydrolysis in the past. This work paves a new perspective in studying catalysts for hydrogen generation from borohydrides. [Display omitted] • Ni–CoP catalyst was electrodeposited on a carbon support. • Material characterization proved the formation of desired active layers. • High efficiency and stability of the catalyst for a long-term NaBH 4 hydrolysis was revealed. [ABSTRACT FROM AUTHOR]

Metal hydride (MH) suffers from strong thermal effects during hydrogen absorption. To fully utilize the reaction heat during hydrogen absorption, phase change material (PCM) can be used to achieve efficient thermal management in the reactor. A novel MH-PCM reactor with the partition arrangement of MH and PCM was proposed in this paper. Then, the two-dimensional multiphysics coupled model of the reactor was developed, and the effects of the number of partitions n , the mass of PCM and the hydrogen absorption pressure P a on the hydrogen absorption performance were discussed detailedly. The results indicated that the novel MH-PCM reactor not only increases the heat transfer area and boots the hydrogen absorption rate, but also improves the uniformity of temperature distribution. As the n increases from 2 to 5, the hydrogen absorption time gradually shortens. Compared to the conventional MH-PCM reactor, the time for 90% hydrogen absorption shortens by 67.13%. Furthermore, the hydrogen absorption rate can be enhanced with the increasing mass of PCM and P a. However, the larger these values are, the weaker the enhancement effect becomes. The results of this paper may provide a new direction for the optimized design and engineering application of MH-PCM reactors. • A novel reactor with the partition arrangement of MH and PCM is proposed. • Effects of partition number, hydrogen storage pressure and PCM mass are examined. • Novel reactor boosts hydrogen absorption rate and improves temperature uniformity. • The hydrogen absorption time is shortened by 67.13% via a partition number of 5. • Absorption enhancement ratio reduces as hydrogen pressure and PCM mass increase. [ABSTRACT FROM AUTHOR]

Given that SOF materials have both inorganic and organic properties and are easy to prepare and structurally designable, this paper carries out the microbehavioral analysis and membrane design of SOF-8, SOF-9, and SOF-10 membranes for the hydrogen purification process of RMFCs. Since three materials have complementary performance characteristics for hydrogen purification, this paper focuses on the gas separation behavior of these three composite membranes using molecular dynamics simulations. Results showed that the SOF-9a+10a composite membranes could 100% block CO 2 and CO, and displayed an excellent H 2 permeability of 6.118 × 105 GPU during H 2 /CO 2 separation, which exceeded the industry standard by nearly 105 times. Additionally, the SOF-9a+8 and SOF-10a+8 composite membranes improved gas selectivity and maintained high H 2 permeability. Moreover, microdiffusion analyses revealed that the small pore sizes and irregular-shaped pore channels effectively hindered CO 2 and CO transport. Microscopic analysis shows the potential of SOF composite membranes for gas separation. [Display omitted] • SOF composite membranes can effectively improve gas selectivity. • Small pore sizes and irregular pore channels can effectively block CO 2 transport. • SOF-9a+10 can 100% intercept CO 2 and CO. • The interaction between gas and membrane affects the gas separation performance. [ABSTRACT FROM AUTHOR]

With the wide application of hydrogen, the research related to 70 MPa pressure level hydrogen storage tank is very important. This paper takes the 70 MPa hydrogen storage tank in the hydrogen refueling station as the research object, and analyses the diffusion characteristics of hydrogen after leakage from the tank under different wind conditions by FLUENT. Studies find that after hydrogen ejects to the obstacle by the effect of high-pressure, it transforms to be dominated by the simple diffusion and the wind condition. The ambient wind helps to reduce the volume fraction of hydrogen. This paper proposes risk mitigation measures based on the distribution of the flammable clouds — installing nitrogen outlets and reducing the height of the enclosure. The volume of flammable clouds is reduced from about 2.72 m3 to less than 0.045 m3 after adding measures, which proves the feasibility of the measures. • A hydrogenation station model is established to simulate the leakage of a 70 MPa hydrogen storage tank. • The diffusion of hydrogen under different wind conditions is compared. • Risk mitigation measures based on the distribution of flammable clouds are proposed and validated. [ABSTRACT FROM AUTHOR]

The global pursuit of sustainable energy solutions has led to an increased interest in green hydrogen as a significant contributor to the transition towards a low-carbon economy. This comprehensive analysis delves into the progress made in green hydrogen production using alkaline water electrolysis, shedding light on the fundamental principles, materials, design, operational conditions, and integration with renewable energy sources. The paper critically evaluates the economic and environmental aspects, providing valuable insights into the challenges, future prospects, and real-world applications. The importance of green hydrogen as a clean energy carrier is emphasized in the context of mitigating climate change and achieving energy independence. The paper outlines various methods for hydrogen production, with a focus on alkaline water electrolysis, highlighting its role in sustainable hydrogen generation. The structure of the review paper is well-detailed, guiding the reader through a systematic exploration of key aspects related to green hydrogen production. The fundamentals of alkaline water electrolysis are explained in detail, covering the basic principles, reactions at electrodes, components, working mechanisms, efficiency calculations, and existing challenges. An in-depth examination of materials and electrodes is presented, showcasing recent innovations that enhance performance. Electrolysers design and system configurations are discussed, incorporating recent developments aimed at improving efficiency and scalability. The paper explores operating conditions and optimization strategies, emphasizing the impact of temperature, pressure, and current density on electrolysis efficiency. The integration of renewable energy sources, such as wind and solar power, with alkaline water electrolysis is analyzed, addressing both the benefits and challenges. The economic feasibility of green hydrogen production and its environmental impacts, including life cycle assessments and carbon footprint, are meticulously examined. The paper concludes with an overview of current challenges and limitations, ongoing research insights, and future prospects for alkaline water electrolysis technology. Real-world case studies are presented to showcase the practical applications of this technology in industries, transportation, and energy storage. In summary, this review highlights the pivotal role of alkaline water electrolysis in advancing green hydrogen production, offering a promising pathway towards a sustainable and decarbonized energy future. [ABSTRACT FROM AUTHOR]

Currently, hydrogen generation is considered a crucial aspect of sustainable energy production. This paper disscusses the hypothesis that hydrogen generation occurs during the operation of the membrane electrode assembly and is an acceptable and eco-friendly method for producing hydrogen without carbon dioxide. This paper considers the hypothesis by simulating hydrogen generation in fuel cells that rely on fossil fuels using proton fuel cells. The O ptimized H ydrogen G eneration-based R egression (OHGR) model is based on a deep learning architecture. The architecture is based on stacking multiple neural networks with crossover connections that feed information through a pool of activation functions. The OHGR predicts the amount of hydrogen generated in 1 mA cm−2 and can exceed 10–20 mA cm−2 after long-term operation. For given temperatures, pressures, and humidity, which are considered fundamental factors in the hydrogen crossing phenomenon.The OHGR uses a stochastic gradient as an optimization engine that informs the most-recommended values for temperature, pressure, and humidity to generate the optimal amount of hydrogen. In addition, the OHGR model is interoperated to accept the same number of most significant features obtained from the principal component analysis. The OHGR was evaluated using empirical regression evaluation metrics, including the root mean square error, R2, Mean Square Error, and Mean Absolute Error. The optimization process was designed to include the hypothesis and hyperparameters to determine the most significant values for the OGHR and its outcomes. The introduced OHGR model is sufficiently efficient to predict the generated hydrogen with RMSE = 0.220 and R2 = 0.564, indicating an enhancement of the OHGR model compared to recently reported models. Since the sustainability of hydrogen generation is important for energy availability and reducing climate change, the OHGR model is justified using the SHapley Additive exPlanations (SHAP) method to ensure that the model is transparent, reliable, and trustworthy. [Display omitted] • Optimized Hydrogen Generation-based Regression (OHGR) model using a custom architecture. • OHGR predicts generated hydrogen PEM by optimizing temp, pressure & humidity of CNN structure. • OHGR uses an optimization engine to detect most recommended to generate hydrogen. • OHGR accepts same number of significant features by principal component analysis. • XAI is used to ensure transparent, reliable, and trusted of OHGR using SHAP. [ABSTRACT FROM AUTHOR]

Hydrogen is emerging as a critical player in transitioning to sustainable and renewable energy systems, serving roles in energy storage, grid balancing, and decarbonization. This paper explores various aspects of hydrogen, including its production through renewable-electricity-driven electrolysis, advanced storage techniques, and incorporation into current energy systems. It highlights primary electrolysis methods like PEM and alkaline, noting their improved efficiency and cost-effectiveness. Various hydrogen storage methods, such as physical, chemical, and advanced porous materials, are examined for their benefits and limitations. The review further explores hydrogen's integration into grid storage systems and microgrids to enhance energy reliability. It discusses hydrogen's application in fuel cells for electricity generation, focusing on technological advancements that improve efficiency and reduce costs. Additionally, the paper underscores hydrogen's crucial role in reducing CO 2 emissions in industrial processes like steel production and its use in residential and commercial energy supply through combined heat and power systems. Economic aspects and supportive policies from regions are analyzed, highlighting the global efforts and policies supporting the potential hydrogen in renewable energy systems. This analysis emphasizes hydrogen's comprehensive role in enhancing renewable energy systems and achieving global sustainability objectives, providing a thorough review of recent progress and challenges. • Identifies PEM and alkaline as efficient electrolysis methods. • Analyzes varied H 2 storage options for mobility and stationarity. • Highlights advancements in H 2 fuel cells for vehicles. • Discusses global policies supporting H 2 integration. • Reviews economic impacts of scaling H 2 infrastructure. [ABSTRACT FROM AUTHOR]

Green hydrogen is typically produced by water electrolysis. In this process, water is split into hydrogen and oxygen by an electric current. Different technologies exist to produce hydrogen by electrolysis, including the four best recognized: Anion Exchange Membrane (AEM), Solid Oxide Electrolysis Cell (SOEC), Polymer Electrolyte Membrane (PEM) and Alkaline Water Electrolysis (AWE). While the latter two are commercially available, SOEC shows promise for efficient hydrogen production, and AEM combines advantages from both AWE and PEM systems. However, the most mature technology remains the most mature and cost-effective technology for industrial and large-scale hydrogen production. This review provides a comprehensive overview of recent advances in alkaline water electrolysis (A-WE) for hydrogen production, including a comparative assessment of the four commonly used electrolysis technologies. The paper covers the current status, recent research advances, and commercialization challenges of A-WE technology, offering insight into its potential and outlining future research directions. • The paper comprehensively assesses A-WE, PEM, SOEC, and AEM technologies for green hydrogen production. • Alkaline Water Electrolysis (A-WE) is the most cost-effective and mature technology for large-scale hydrogen production. • A-WE's limitations include low current density, corrosivity, gas permeation, slow response, and sensitivity to impurities. • Advanced materials, optimized electrolytes, membranes, and innovative electrode designs enhance A-WE performance. • A-WE market saw 6.5% CAGR growth, driven by sustainable energy demand despite supply chain and geopolitical challenges. [ABSTRACT FROM AUTHOR]

The clean transformation of building energy consumption is a critical pathway for achieving deep decarbonization. In light of the diversity of building energy needs, this paper proposes an integrated zero-carbon energy supply building architecture that involves the coupling of electrical, hydrogen, heat, and cooling energy sources. To address challenges in real-time supply-demand balancing and reliability of supply under extreme or boundary conditions due to complex energy couplings, the paper introduces an energy management framework with two control layers comprising mixed-integer linear programming (MILP) and model predictive control (MPC). This framework conducts hierarchical optimization to synergize economic and technical objectives. At the economic optimization layer, optimal economic parameters are formulated based on MILP; while at the MPC optimization layer, these parameters serve as reference states. By incorporating state relaxation method, the framework accommodates the uncertainties associated with system operation. Simulation analyses of typical weeks during summer and winter seasons demonstrate that the energy optimization management approach proposed in this paper can achieve highly reliable and economically stable operation of the building energy supply system. • A zero-carbon energy supply building energy structure is constructed. • Dynamic evolution model of electricity-hydrogen-heat-cooling multi-energy coupling system is established. • A double-layer energy management method including economic optimization and MPC optimization is proposed. [ABSTRACT FROM AUTHOR]

The application of hydrogen energy is affected by the safety of hydrogen storage system. To grasp the current status of research and application in the research field of hydrogen storage safety and explore its research development trend, data analysis techniques, such as co-occurrence, co-citation, and burst detection, were adopted to conduct bibliometric analysis of the relevant literature. The study results show that the research hotspots of hydrogen storage safety mainly concentrate on six aspects: the stability of metal hydride hydrogen storage materials, the study of thermal management and stress relief in metal hydride reactors, the safety analysis of hydrogen fuel cells and hydrogen leakage monitoring, the analysis of leakage and explosion risks in hydrogen refueling stations, the study of filling pressure and temperature distribution in hydrogen storage tanks, and the study of safety issues in underground hydrogen storage. Mg-based hydride stability and underground hydrogen storage risk analyses are current research frontiers in hydrogen storage safety. • This paper presents the development of hydrogen storage in safety research. • 1552 papers are visualized and analyzed using bibliometrics. • Identifying research frontiers by combining timeline view with burst detection. • Knowledge bases, research hotspots, and frontiers are discussed. • The current challenges and perspectives for the future are proposed. [ABSTRACT FROM AUTHOR]

The transition to sustainable energy sources is a global imperative in the face of climate change and dwindling fossil fuel reserves. Hydrogen, as a clean and versatile energy carrier, has garnered significant attention as a potential solution. This paper provides a comprehensive overview of various electrolyzer types, their features, advantages, disadvantages, and future expectations in the context of sustainable energy generation. The article begins by outlining the fundamental principles of electrolysis, highlighting its potential to harness surplus renewable energy. Four main types of electrolyzers are discussed: alkaline electrolyzers, proton exchange membrane electrolyzers, anion exchange membrane electrolyzers, and solid oxide electrolyzers. Each type is explored in depth, with a focus on their unique operating principles, efficiency, scalability, and suitability for different applications. The paper further delves into recent advancements in electrolyzer technology, discussing emerging trends, improved catalysts, and innovative system designs aimed at enhancing efficiency and reducing costs. It also explores the role of policy support and research initiatives in accelerating the adoption of electrolysis for sustainable hydrogen production. • Water electrolyzer systems are one of the most promising technologies for green hydrogen production. • This review provides insights into the current state and future potential of water electrolysis technologies. • Challenges, advantages, and future directions of electrolyzer types are discussed. • Green hydrogen plays a crucial role in decarbonization efforts and offers a sustainable solution for future energy needs. [ABSTRACT FROM AUTHOR]

Blue hydrogen (H 2) serves as a pivotal initial step towards emissions reduction and a seamless transition to green hydrogen by providing a cleaner alternative to grey hydrogen. Blue H 2 can be obtained through diverse pathways (i.e. , distinct processes and stages) within the hydrogen supply network (HSN), resulting in varying greenhouse gas emission levels. This paper uses the Life Cycle Assessment methodology to compare 18 different blue HSN pathways. Blue hydrogen is produced from three different processes (i.e. , Steam Methane Reforming (SMR), Partial Oxidation of Methane (POM), and Auto-Thermal Reforming (ATR)) that are coupled with carbon capture unit (CCU). Moreover, it can be conditioned to different states or carriers (i.e. , liquefied H 2 , compressed H 2 , ammonia, and methanol), stored using various methods, transported by different means according to its state, and reconditioned to its original state at end-users. The LCA results indicate that the NH 3 pathway has the least environmental impact measuring just 2.12 kgCO 2equ / kgH 2 compared to the other 18 blue HSN pathways. This pathway involves producing hydrogen from ATR process coupled with CCS, and eventually delivering as ammonia to consumers. Additionally, the blue H 2 results of this paper are compared to the green H 2 results discussed in the previous paper. The comparison highlights that integrating renewable energy in the form concentrated photovoltaic collectors produces the lowest emissions compared to all pathways. It reduces the emissions from 45.3% to 67% depending on the pathways, compared to the ATR process coupled with CCU. • SMR, POM, or ATR with carbon capture for blue hydrogen production. • This LCA study compares 18 blue HSN pathways for their environmental performance. • Different pathways within the HSN lead to various levels of GHG emissions. • NH 3 path emits the least emissions (2.12 kgCO 2equ /kgH 2) among blue H 2 paths. • CH 2 path emits the least emissions (0.080 kgCO 2equ /kWh) among all paths. [ABSTRACT FROM AUTHOR]

The uncertainty of renewable energy undermines the competitiveness of Renewable Energy Generation Companies (REGC) in market bidding. Hydrogen energy storage, as a novel high-energy-density energy storage technology, is considered an ideal solution to address the uncertainty of renewable energy and provide flexible ramping products (FRP) to the grid. Building upon this, this paper combines hydrogen energy storage and renewable energy to build a hydrogen-wind-photovoltaic (HWP) system, and introduces HWP into the flexible ramping market for the first time, while participating in the energy market. To capture the interactions between HWP and market players with different utility functions, this paper establishes a bi-level bidding strategy model for HWP participation in the integrated energy and flexible ramping markets, It enables HWP to optimize its internal unit output to increase revenue based on current market conditions. In addition to this, the uncertainty of renewable energy output is taken into account in the upper-level model. Finally, the effectiveness of the proposed two-stage stochastic bi-level optimization scheduling model was validated on IEEE 6-bus and 36-bus transmission-constrained networks. Tests demonstrated that the proposed model effectively assists HWP in formulating optimal bidding strategies in the joint market under uncertainty. Compared to solely participating in a single energy market, HWP's simultaneous participation in energy and flexible ramping markets increased total revenue by 12.22%. • Utilizing hydrogen energy storage to provide Flexible Ramping Product (FRP). • Hydrogen-Wind-Photovoltaic (HWP) participates in energy and flexible ramping market. • Establishing a bi-level strategic bidding model for HWP. • Considering the influence of renewable energy uncertainty on bidding strategies. • The introduction of the FRP increased HWP's total revenue by 12.22%. [ABSTRACT FROM AUTHOR]

This paper considers an electric-hydrogen hybrid energy storage system composed of supercapacitors and hydrogen components (e.g., electrolyzers and fuel cells) in the context of a microgrid with photovoltaic generators. To manage the power and hydrogen flows within the microgrid and coordinate the coupling between the microgrid and a hydrogen refueling station, this paper proposes an energy management framework. The outer layer of the framework takes the hydrogen compressor power as part of the microgrid load and optimizes the hydrogen flow from the microgrid to the hydrogen refueling station. The inner layer develops a two-stage scheme to optimize the power allocation between the electric and hydrogen systems within the microgrid. A low pass filter with an adaptive cutoff frequency is utilized to split the net load power of the microgrid into high-frequency and low-frequency components, which are then assigned to the electric and hydrogen systems, respectively. The adaptive cutoff frequency is determined based on the power split factor tuned twice during the two stages of the power allocation scheme based on the supercapacitor state of charge. The effectiveness of the proposed framework is validated by performing real-time simulations using a dSPACE platform. • Proposes an energy management framework for electric-hydrogen systems. • Optimizes the hydrogen flow from the microgrid to the hydrogen refueling station. • Develops a two-stage power allocation scheme based on artificial potential field. • Validates the framework using a dSPACE DS1202 real-time simulation system. [ABSTRACT FROM AUTHOR]

The durability is a key factor of fuel cell in large-scale application of automobiles. It is great important to real the lifetime and health status of fuel cells, especially in vehicle driving conditions. Based on the experimental data, this paper used the model-based method and data-driven method to predict the life of fuel cells, respectively. The model-based method established the equivalent circuit model according to the mapping law of electrochemical impedance spectroscopy (EIS) and the parameters of the equivalent circuit model were identified by newly considering the phenomenon of voltage recovery, revealing the strong linear correlation between impedance and voltage. The data-driven method selected a combinatorial optimization PSO-LSSVM algorithm and compared it with the prediction results of MATLAB's time series toolbox. The results show the mean square error (MSE), End of Life (EOL) of the model-based method, the time series toolbox and PSO-LSSVM algorithm are 0.019, 8.2 × 10−3 and 4.42 × 10−5, the 260h, 438h and 427h, respectively. Comparing with the real EOL of 421h, the error of PSO-LSSVM algorithm is only 6 h, which means the remaining useful life can be predicted with high accurately. Thus this study provides a reference for fault identification and life prediction of fuel cell health management. • The equivalent circuit model is established to realize the segmented voltage prediction and analysis of fuel cells. • The MSE of combinatorial optimized algorithms PSO-LSSVM to predict voltage is only 4.42 × 10−5. • The method in paper provides a reference for fault identification and life prediction of PEMFC's health management. [ABSTRACT FROM AUTHOR]

In the present paper, polyaniline modification of Mn 0.5 Cd 0.5 S composite (PANI/MCS) was fabricated by a simple electrostatic adsorption method. The introduction of PANI makes PANI/MCS composites have better visible light absorption and higher photogenerated carrier segregation efficiency, thus showing better photocatalytic performance. The results show that the 50-PANI/MCS photocatalyst has the best hydrogen production capacity, which was 2.2 times greater than neat MCS. Meanwhile, the nitrogen fixation performance of the best sample 50-PANI/MCS was 4.93 times that of pure MCS. After that, a reasonable reaction mechanism was obtained through various characterization data. A cheap and readily available composite photocatalyst has been synthesized. This paper has good reference value in the area of development of efficient composite photocatalyst. In this paper, polyaniline modified Mn 0.5 Cd 0.5 S composite (PANI/MCS) was prepared by simple electrostatic adsorption. The introduction of PANI makes PANI/MCS composites have better visible light absorption capacity and higher photogenerated carrier separation efficiency, thus showing better photocatalytic performance. The results show that the 50-PANI/MCS photocatalyst has the best hydrogen production capacity, which is 2.2 times that of pure MCS. At the same time, the nitrogen fixation performance of the best sample 50-PANI/MCS was 4.93 times that of pure MCS. A cheap and readily available composite photocatalyst has been synthesized. [Display omitted] • A new method for the modification of Mn x Cd 1-x S by conductive polymer was proposed. • The whole prepared process of PANI/MCS composite material is cheap and simple. • PANI/MCS exhibits accelerated photogenerated carrier separation. • PANI/MCS exhibits better hydrogen evolution and nitrogen fixation performance. [ABSTRACT FROM AUTHOR]

Nowadays, hydrogen is gaining attention as one of the green energy alternatives within transition to a zero-emission economy. Increasing demand for hydrogen and its production has prompted the development of low-carbon strategies and technologies for hydrogen generation from hydrocarbons. This paper provides a thorough analysis of traditional and innovative methods for hydrogen production from fossil feedstock, reviewing the critical aspects and recent advancements in the field. The paper emphasizes the potential of in situ hydrogen generation as the most promising method, taking into account CO2 emission concerns. Additionally, this study explores the use of software packages for modeling hydrogen production, outlining their advantages and disadvantages and proposing the most favorable software for in situ hydrogen generation from hydrocarbons. Subsequent analysis sheds light on the effectiveness, economic viability, environmental impact, and future perspectives of various hydrogen production technologies. • Overview of hydrogen production technologies: conventional and innovative methods. • Key issues and best practices of the latest experimental and numerical studies. • Comparative analysis of various hydrogen production technologies and approaches. • Subsurface hydrogen generation has a great development potential. • There are methods for clean hydrogen production from hydrocarbon feedstock. [ABSTRACT FROM AUTHOR]

The desublimation crystallization of trace impurity gas at the temperature of liquid hydrogen and liquid oxygen is a common problem in cryogenic engineering, which usually leads to the failure of cryogenic liquid transportation. Liquid hydrogen and liquid oxygen are important aerospace propellants. In the pressurization process of cryogenic liquid propellant, a small amount of water vapor and other gases in the pressurized gas would appear desublimation and crystallization at low temperature. Inevitably, as the tail gas of hydrogen combustion, water vapor sometimes diffused into cryogenic liquid. This kind of desublimation crystallization was accompanied by heat and mass transfer, accompanied by gas-solid phase transition, moving boundary, random and extremely complicated crystallization growth process. It was of great engineering practical significance to study the heat and mass transfer mechanism and law of this complex desublimation phase change phenomenon for the progress and development of engineering technologies such as refrigeration, cryogenics and aerospace. In this paper, based on the homogeneous desublimation theory, the pressurization system of liquid oxygen tank with oxygen containing trace water vapor was taken as the research object, and the basic data of ice crystal formation and growth during pressurization, such as crystallization quantity, crystallization speed and size distribution, were calculated theoretically. It provided a theoretical basis for the experimental study of the real dynamic characteristics and laws of desublimation crystallization in the propulsion system. The research methods and conclusions in this paper also had some guiding significance for the use of liquid hydrogen in the storage, transportation and use of the hydrogen energy. • Provided a challenging crystallography study on the space application of liquid hydrogen and liquid oxygen. • Described the complicated desublimation crystallization with accompanied by heat and mass transfer. • Provided dynamic characteristics of crystallization quantity, crystallization speed and size distribution. • Simulated the nucleation and ice growth accurately for many generations crystals evolved. • Suitable for crystallization of trace impurities during liquid hydrogen storage and transportation. [ABSTRACT FROM AUTHOR]

Hydrogen transfer leaks are one of the most important life-limiting faults in polymer electrolyte membrane fuel cells (PEMFCs). Hydrogen transfer leaks result in a reduction in the amount of oxygen available in the cathode (air) channel, with large leaks resulting in oxygen starvation and hydrogen emission. This paper aims to develop an adaptive extended Kalman filter (EKF) to estimate the unknown oxygen concentration, which is then used to infer hydrogen leaks. To this end, the paper first develops the lumped model of the fuel cell from a pseudo-2D model of a fuel cell. Next, a (non-adaptive) EKF is developed to estimate the fuel cell states under both normal and oxygen-starved conditions. The adaptive EKF is then implemented by adding the unknown hydrogen leak to the list of estimated states. Finally, the paper demonstrates the efficacy of the proposed adaptive EKF by using it to accurately estimate unknown hydrogen leaks in a high-fidelity virtual fuel cell under excessively noisy conditions. • Adaptive extended Kalman filter under normal and starved conditions. • Detects leaks under the presence of excessive noise. • Uses transient model of starved fuel-cell capturing voltage. • Based on previously validated pseudo-2D model. • Transient response agrees with simulated experiments. [ABSTRACT FROM AUTHOR]

Hydrogen as a clean energy to deal with carbon emissions has been favored by many scholars, while the problems of low efficiency and high energy consumption in the process of liquefaction storage and transportation have become one of the important factors restricting the development of it. The combination of heat exchanger and ortho-para (O–P) hydrogen converter has attracted considerable attention as a high efficiency and low energy consumption technology. In this paper, based on the catalyst-filled spiral wound heat exchanger (CSWHE) and coupled with ortho-para hydrogen conversion, the flow and heat transfer characteristics of gaseous hydrogen are studied. Firstly, low-temperature O–P hydrogen catalytic conversion experiments and flow characteristics experiments were carried out by filling catalyst in the heat exchange tube. and an equation for calculating pressure drop in the section filled catalyst was proposed. Secondly, a new numerical model was established validated by the experiments. The influence of catalyst on heat transfer and the effects of velocity on the heat transfer performance and O–P hydrogen conversion efficiency were studied by numerical simulation. Finally, this paper analyzed the significant factor affecting the para hydrogen content at outlet: reaction time. And an equation for calculating para hydrogen content at outlet with reaction time was proposed. This study is expected to provide a reference for the design of CSWHE. • An isothermal reactor is designed and employed to low-temperature ortho and para hydrogen catalytic conversion experiments. • A new pressure drop calculation equation for porous region is proposed by modifying Ergun equation. • A new numerical model is established to study the coupling mechanism of flow and heat transfer. • The key factor affecting the catalytic conversion of ortho and para hydrogen is pointed out: reaction time. [ABSTRACT FROM AUTHOR]

This paper presents a detailed review of the plasma gasification process for waste disposal. Due to Shifting economies and consumerism culture, ample change can be seen across the globe in the form of rapid industrialisation and burgeoning urbanisation, which results in a massive increase in waste generation. Plasma gasification technology is an emerging solution for processing a wide range of waste making it a highly sustainable, efficient, and ecologically sound process. This literature review discusses the feasibility of the plasma gasification method and its superiority over other conventional waste disposal techniques. A comprehensive analysis of different methods of plasma generation for gasification is done in this literature review. The review paper presents a detailed coverup of the entire process of plasma gasification and post-processes. The article discusses the notable advancement, current scenario, and possibilities in plasma gasification methodology in terms of the design of plasma torch, modelling of gasifiers, generation of syngas, and power production. It provides an overview of advanced simulation tools helpful in the analysis of the Waste-to-Energy (WtE) process. This literature review aims to provide an overview of the recent advances in plasma gasification, highlighting the technical aspects, environmental benefits, and economic viability of the technology. It also reviews the latest research and developments in plasma gasification and discusses the challenges and limitations of the technology, as well as the future prospects and potential applications. • Plasma gasification methodology for waste treatment is discussed in detail. • Prominent thermal and non-thermal practices are discussed and compared in this literature review. • Selective use of plasma gas for enhanced efficiency and optimised gas yield/composition. • Hybrid systems offer versatility in processing diverse feedstocks and can achieve higher energy efficiencies. • Plasma-catalysis approach with NTP shows desirable syngas yield. [ABSTRACT FROM AUTHOR]

Research on proton exchange membrane water electrolysis for renewable hydrogen production is rapidly advancing worldwide, driven by the imperative to reduce costs and enhance efficiency through development of novel materials. However, to effectively evaluate and validate these advancements, standardized testing methods are essential, extending beyond single-cell analysis to encompass stack-level characterization. This paper proposes comprehensive characterization methods tailored for analysis of electrolysis stacks and their performance characteristics. Each method is introduced with a focus on its practical applicability, accompanied by detailed procedural guidelines for implementation. Furthermore, variations within each method are discussed, offering possibilities for gathering additional insights. Presenting a portfolio of different methods, ranging from standard to advanced techniques applicable at the stack level, the paper showcases results obtained through their application. These results, normalized to cell area, demonstrate the significance of each method in obtaining stack characteristics crucial for informed design decisions on material selection and subsequent integration into electrolysis systems. By illustrating results derived from various stacks, this study contributes valuable insights for evaluating design, material suitability, and operational performance, thereby advancing the development and deployment of proton exchange membrane water electrolysis technology for sustainable hydrogen production. • Development of benchmarking and testing protocols for PEM water electrolysis. • Utilization of cyclic voltammetry for assessing degradation effects in electrolysis stacks. • Experimental analysis of system and stack loss mechanisms. • Identification of key elements monitor degradation effects on stack and system level. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cells (PEMFCs) offer high energy conversion rate and low pollution, while low durability of PEMFCs hinder the further development. Accurately predicting degradation trends and remaining useful life (RUL) are crucial to timely detecting problem and improving PEMFCs durability. In this paper, an enhanced transfer learning (Add-TL) based on adder network (AdderNet) and deep domain confusion is proposed for the prediction of PEMFCs. To reinforce the ability of extracting key features from extensive data, AdderNet with attention mechanism is applied. Furthermore, the fused deep domain confusion employs existing data to achieve higher prediction accuracy. The experimental results demonstrate that Add-TL outperforms other classical methods in predicting degradation trend, the optimal adjusted R-square (R2) values for the two datasets are 0.99879 and 0.99906, respectively. When Add-TL is applied to RUL prediction, the accuracy scores for two datasets reach 0.995, which further validating the applicability of Add-TL in PEMFCs prediction. • AdderNet applied for the first time to predict degradation trends and RUL of PEMFCs. • The method proposed in this paper integrates deep learning and transfer learning. • The incorporation of transfer learning the connections between data, aiming to improve the accuracy of RUL prediction. • Add-TL predicted static and dynamic conditions, providing a comprehensive validation. • Add-TL achieves best performance when training on datasets with varying lengths. [ABSTRACT FROM AUTHOR]

Oxygen excess ratio (OER), which is influenced by the air flow input to the cathode, is one of the important factors affecting the performance of fuel cell system. Insufficient oxygen supply will result in a sharp drop in output voltage, while an excessive supply will bring about a large parasitic power load on the air compressor, reducing the net output power of the system and operating efficiency. Both insufficient and excess oxygen supply can adversely affect the operating life of the proton exchange membrane fuel cell (PEMFC). Due to the serious nonlinear, hysteresis, uncertainty and interference in the process of OER control, this paper proposes an OER feedforward control based on extended state observer (ESO) for a PEMFC auxiliary system with the ESO to predict the total disturbance to improve the dynamic response of the system with large time delay utilizing terminal sliding mode control (TSMC). The control strategy is divided into two stages. The first stage constructs an ESO to realize real-time observation of the state variables required for the internal operation of the auxiliary machine system and the PEMFC, and yields the air compressor voltage control signal through terminal sliding mode control. In the second stage, combined with V/f control for the compressor, the transmitted air flow is adjusted, ultimately achieving the goal of changing the OER of the PEMFC and improving operating efficiency. The simulation results show that the proposed control strategy has good anti-interference capabilities, a faster response, and less overshoot. The gas flow transmission in the gas supply system is more robust, the PEMFC operation is safer, and its lifespan is extended. • The control difficulty caused by time delay characteristics of gas transmission in hydrogen production system considering gas-electric coupling is overcome. • The additional ESO can well observe the state variables and external disturbance that cannot be directly measured in the PEMFC system. The closed-loop control based on TSMC of the system is realized more accurately. • This paper considers the situation that when the energy storage system cannot meet the energy demand, PEMFC still wants to provide continuous power output. An adjusting strategy for OER in PEMFC through the electromagnetic effect of air compressor to extend the life span of the PEM fuel cell is proposed. • The proposed OER feedforward control strategy demonstrated superior robustness and fast response characteristics for oxygen excess ratio optimization. [ABSTRACT FROM AUTHOR]

The escalating demand for renewable energy solutions and the imperative for efficient energy storage mechanisms have catalyzed the evolution of Power-to-X (PtX) technologies. Germany has the most PtX projects, accounting for 44% of all projects that have been reported. PtX encompasses a spectrum of processes engineered to convert surplus renewable energy into versatile energy carriers or chemical commodities, such as hydrogen, methane, or synthetic fuels. The Paramount to this domain is to synergistically harness renewable energy sources and hydrogen carriers to curtail waste and bolster sustainability. Central to achieving this synergy is the effective control of PtX processes, ensuring optimal performance, cost efficiency, and seamless integration within existing energy frameworks. This paper delves into the control processes and environmental prerequisites within the PtX landscape, elucidating key challenges, and strategies within this dynamic realm. While providing an initial overview of fundamental PtX process chains, this paper accentuates the critical role of geographical considerations. Subsequently, it conducts a thorough analysis of equipment modeling challenges, addressing performance metrics, operational requisites, and capital investments, particularly focusing on methanol and hydrogen production and storage. Through holistic examination, this paper endeavors to delineate the evolving landscape of PtX control processes and conditions, advancing our understanding of this expanding field. [Display omitted] • Comprehensive overview of PtX control process, challenges, strategies, and advancements. • Overview of PtX process chains and geographical conditions. • Analysis of equipment modeling challenges for methanol and hydrogen. • Addressing crucial storage challenges in PtX system. • Exploration of diverse influences on PtX control processes. [ABSTRACT FROM AUTHOR]

Stationary hydrogen energy-based power plants generating electricity to supply high-powered plug-in electric vehicles (PEVs) have recently become popular in renewable energy-based power plants. Besides, in a PEV charging station, various types of powered charge devices can be established such as DC fast chargers or 3.7 kW, 7.4 kW, 11 kW, and 22 kW AC chargers. This paper introduces a demand-side management-oriented optimal charging strategy that includes two stages for PEVs in a hydrogen energy-based microgrid. The paper focuses on two stages to execute an optimal charging of PEVs in compliance with their users' requests and satisfaction and considering the power system loading. It is assumed that there are three types of chargers in the PEV charging station and the users. In the first stage randomly created requests are classified by an ensemble learning classifier method that performs higher performance classification by combining the results from multiple classifiers in a machine learning classification. The second stage schedules the PEVs according to the classification results and users' requests. To test the proposed system, first random requests are created then they are sent to the classifier, and the results of classifiers are scheduled in each other. The demand-side management-oriented charge scheduling and managing strategy which includes the proposed two stages has been compared with non-managed cases. Case study results reveal that the proposed approach provides 52.1% peak load reduction and 72.3% valley filling improvement by the SOS algorithm. The results highlight the advantages of the proposed system in terms of peak reduction and valley filling. [Display omitted] • A new intelligent decision-maker method is proposed for DSM in a microgrid. • Proposed method is developed for a stationary hydrogen energy-based power plant. • The optimal DSM of EVs is investigated with a hybrid ML method. • RUSBoost and SOS Algorithms-based Hybrid Intelligent Decision Maker is developed. • It provides 52.1% peak load reduction and 72.3% valley filling improvement. [ABSTRACT FROM AUTHOR]

This paper examines the potential of solar and hydrogen (H 2) energy-based hybrid energy systems for residential applications. The growing need for energy and the demand for sustainable energy sources have led to the development of integrated energy systems that combine renewable energy resources to meet energy needs. This paper overviews recent studies on hybrid energy systems for on-grid and off-grid residential utilizations. It discusses the system configuration and components of hybrid energy systems, including solar panels, electrolyzers, fuel cells (FC), and batteries. It also covers the technical optimization of integrated energy systems, including sizing, control strategies, and economic analysis. The key findings of this review paper indicate that hybrid energy systems can offer dependable and sustainable energy for residential applications. Through numerical analyses, the optimal dimensioning of the system elements and control strategies can significantly enhance the system's performance and lower the cost of energy. This study also highlights the challenges and opportunities for integrating hybrid energy systems within residential applications. Overall, it provides in-depth perspectives on the possibilities inherent in solar and hydrogen energy-based hybrid energy systems for residential applications. The findings can guide future research and the advancement of hybrid energy systems for sustainable energy solutions. • Comprehensive review on solar and hydrogen-based residential applications. • Holistic approach to system configuration, optimization, and economics. • Detailed analysis of interconnected components enhancing system efficiency. • Unique focus on real-world residential applications and scenarios. • Broad applicability across diverse geographical regions. [ABSTRACT FROM AUTHOR]

Hydrogen is an ideal energy source and plays an important role in increasingly global energy issues and environmental problems. Liquid hydrogen (LH2) has many advantages over other storage methods, especially in terms of energy density. However, it may cause enormous harm once it leaks accidently. LH2 leakage is a complex multiphase process involving evaporation, condensation, transfer of mass and heat, and dispersion. In order to study LH2 transportation and storage systems safety, a research project has been carried out to develop a 3D numerical model using an open-source CFD code, OpenFoam, for investigating LH2 accidental release scenarios. Since the release of LH2 is a very complex process, our strategy is to study it step by step. Therefore, in this paper we present our research work at the first stage, a dispersion process of room-temperature gaseous hydrogen without multiphase flow. A small-scale hydrogen release conducted by Sandia National Laboratories is simulated. In this experiment, room-temperature gaseous hydrogen is injected upwards into the air from a small hole with a 1.91 mm diameter. The situations of Froude (Fr) number = 99, 152, and 268 are studied, respectively. The behavior of hydrogen at different Fr numbers is discussed. When high-speed hydrogen enters the air, the speed and concentration of hydrogen decrease rapidly. In addition, the greater the speed, the faster it decays. The result shows a close range of hydrogen reach. Details about the numerical model are introduced. The simulation results are used to verify the validity of the developing numerical model for dispersion and mixing of multi-species. The simulated concentrations and velocity distribution are analyzed and compared with experimental data. The simulation shows a good agreement with the data of Sandia National Laboratories. The agreement between experiments and simulations is measured using the Pearson correlation coefficient (>0.98), which indicates excellent consistency. In the next step, we will integrate the multiphase flow and phase change into the current model. The phase change of liquid hydrogen and air will be simulated to study the release of liquid hydrogen. • Using the open-source CFD code OpenFOAM for simulation of hydrogen jet. • A good agreement between the simulations results and experimental data has been found in this paper. • When high-speed hydrogen is injected into the air, both velocity and concentration drop rapidly. • Final concentration is not sensitive to different injection velocity. [ABSTRACT FROM AUTHOR]