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This work reports on the synthesis of tin-nitrogen/carbon (Sn–N/C) catalysts suitable for the electroreduction of molecular oxygen at the cathode of proton exchange membrane fuel cells. The catalysts were synthesized through a simple pyrolysis process of folic acid as the carbon and nitrogen source, tin chloride as a tin source and Vulcan carbon as the substrate. The synthesized catalyst exhibited excellent oxygen reduction activity with a half wave potential of 0.82 V and a mass activity of 15.5 mA mg−1. Successful application at the cathode of a self-breathing fuel cell further confirmed the superior performance of this catalyst leading to a power density of 29.4 mW cm−2. This is very comparable to the reference platinum/Vulcan carbon catalyst (28.4 mW cm−2). In addition, this Sn–N/C catalyst showed good stability under accelerated stress tests with only a 12% decrease in fuel cell performance after 10,000 cycles. The superior performance was assumed to be due to the presence of both metal-nitrogen and nitrogen-carbon active sites, which facilitate the four-electron path of the oxygen reduction reaction. A tin-nitrogen/carbon catalyst shows similar performances in polymer electrolyte membrane fuel cells as platinum on Vulcan carbon. [Display omitted] • Tin-nitrogen/carbon electrocatalysts could be synthesized through a simple solid-state route. • These oxygen reduction catalysts exhibited excellent mass activity compared to the state-of-the-art platinum-based catalysts. • When operated in a self-breathing fuel cell, the tin-nitrogen/carbon catalyst achieved the same power density than platinum. [ABSTRACT FROM AUTHOR]

The article presents the result of an experiment which performed scanning electron microsocopy (SEM) analysis for the production of the light grey material (PSTN/MgH2). The experimental variables used include the structure of the magnesium nanoparticle, the role of the azide in the formation of self-assembled nanostructures, and the concentration of polymers. A modification of poly(styrene) and binding ligands is also performed to explore the azide function.

Cytochromes from the SoxAX family have a major role in thiosulfate oxidation via the thiosulfate-oxidizing multi-enzyme system (TOMES). Previously characterized SoxAX proteins from Rhodovulum sulfidophilum and Paracoccus pantotrophus contain three heme c groups, two of which are located on the SoxA subunit. In contrast, the SoxAX protein purified from Starkeya novella was found to contain only two heme groups. Mass spectrometry showed that a disulfide bond replaced the second heme group found in the diheme SoxA subunits. Apparent molecular masses of 27,229 ± 10.3 Da and 20,258.6 ± 1 Da were determined for SoxA and SoxX with an overall mass of 49.7 kDa, indicating a heterodimeric structure. Optical redox potentiometry found that the two heme cofactors are reduced at similar potentials (versus NHE) that are as follows: +133 mV (pH 6.0); +104 mV (pH 7.0); +49 (pH 7.9) and +10 mV (pH 8.7). EPR spectroscopy revealed that both ferric heme groups are in the low spin state, and the spectra were consistent with one heine having a His/Cys axial ligation and the other having a His/Met axial ligation. The His/Cys ligated heme is present in different conformational states and gives rise to three distinct signals. Amino acid sequencing was used to unambiguously assign the protein to the encoding genes, soxAX, which are part of a complete sox gene cluster found in S. novella. Phylogenetic analysis of soxA- and soxX-related gene sequences indicates a parallel development of SoxA and SoxX, with the diheme and monoheme SoxA sequences located on clearly separated branches of a phylogenetic tree. [ABSTRACT FROM AUTHOR]

Self-breathing fuel cells use oxygen directly from the atmosphere and this eliminates the need of air fans and humidifiers, and as such enables applications where a reduction in size and volume of the power systems is important. Herein, we report a novel design and fabrication of a 12 celled cylindrical self-breathing stack made from stainless steel. A cylindrical geometry was implemented to permit higher self-breathing function and means to improve the Membrane Electrode Assembly compaction and thus reduce hydrogen leaks. The stack delivered a maximum voltage of 9.4 V and a maximum power of 1 W cm−2 while operating under ambient condition (25 °C, 20% relative humidity and with dry hydrogen). The stainless steel bipolar plates provided enough compaction to the stack to minimize ohmic resistance and the hydrogen sealing was done with silicon gaskets which facilitated the stacking of the cells. The developed 12 celled stack delivered a volume power density of 29 W per litre which is 80% higher than previously reported self-breathing polymer electrolyte membrane fuel cells. [Display omitted] • A cylindrical self-breathing PEMFC stack was designed to deliver 2 W and 10 V. • A low ohmic resistance was achieved by using stainless steel bipolar plates. • The stack delivered a maximum power density of 1 W cm−2 at 4.2 V. • Self-breathing and self-humidification was verified at 170 mA cm−2 and 5.4 V. [ABSTRACT FROM AUTHOR]

The cover feature shows magnesium crystallites holding hydrogen. When these crystallites are decorated with gold, hydrogen release and uptake can be triggered by sunlight illumination. The findings provide a novel strategy to effectively store hydrogen in materials such as Mg, LiH and NaAlH4. Details are given in the Communication by Y. Sun and K.‐F. Aguey‐Zinsou on page 904 in Issue 10, 2018 (DOI: 10.1002/cplu.201800190). [ABSTRACT FROM AUTHOR]

Graphical abstract Upon nanoconfinement in mesoporous carbon, AlH 3 shows direct hydrogen reversibility. Highlights • AlH 3 was confined within the nanoporosity of high surface area graphite. • Nanoconfined AlH 3 released hydrogen from 60 °C. • Some reversibility was observed at 150 °C and under 60 bar hydrogen pressure only. Abstract AlH 3 (alane) is considered as an ideal one-off compact hydrogen storage material thanks to its high storage capacity and moderate decomposition temperature. However, application has been hindered by the lack of direct hydrogen reversibility, i.e. regeneration of AlH 3 directly from the reaction of spent Al with hydrogen under mild conditions. Herein, we investigated the effect of nanoconfinement on the properties of AlH 3 and the potential of this approach toward the direct release and uptake of hydrogen by nanosized Al. AlH 3 was confined within the mesopores of a high surface area graphite (HSAG). The decomposition of the nanoconfined AlH 3 was detected 50 °C lower than the bulk, showing some effect of nanoconfinement on the overall temperature for hydrogen release. Some hydrogen uptake was also observed at 150 °C and 60 bar hydrogen pressure, and this indicates that reversible release of hydrogen with alane under moderate conditions of pressure and temperature may be possible. [ABSTRACT FROM AUTHOR]

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Platinum (Pt) is the most common catalyst in Polymer Electrolyte Membrane Fuel Cells due to its ability to effectively promote the oxidation of hydrogen and reduction of oxygen. However, as a noble metal, the use of Pt should be minimized. Alloying Pt with low-cost transition metals is an effective strategy to improve catalytic activity and reduce Pt use. In this context, we report on a one-step synthesis of a Platinum/Copper (PtCu) catalyst, which can be used at both the anode and the cathode of a fuel cell. Catalysts with various Cu to Pt ratios were synthesised and in particular the PtCu catalyst at a Cu to Pt ratio of 0.5 demonstrated a high activity for hydrogen oxidation and oxygen reduction, i.e. 2.4 times superior to Pt alone. This enhanced catalytic activity was confirmed in a self-breathing PEMFC with a power output of 45.16 mW cm−2, which corresponds to a 1.4-fold increase compared to Pt alone. This is a significant improvement because 40% more power was obtained with 22% less Pt. [ABSTRACT FROM AUTHOR]

Abstract: Herein, the nanoconfinement of LiBH4 and NaBH4 in a carbon (carbon nanotubes, MBH4@CNT) and an inorganic support (CuS hollow nanospheres, MBH4@CuS) is compared. Both led to drastic improvements in hydrogen storage properties, with hydrogen desorption occurring from room temperature, and the reversibility greatly enhanced. However, successive hydrogen desorption and absorption cycles for MBH4@CNT led to a decrease in hydrogen storage capacity, most likely due to partial oxidation from oxygen-containing groups on the surface of the carbon nanotubes. In contrast, little to no decrease in capacity was observed for MBH4@CuS, indicating that similar materials may be a more viable alternative for future nanoconfinement research. [Copyright &y& Elsevier]

• Upon oxidation, TiFe 0.85 Mn 0.15 can simply be re-activated upon a heating cycle at 300 °C. • Cr addition drastically reduces the effect of oxidation on this alloy and facilitates re-activation. • TiFe 0.85 Mn 0.15 Cr 0.30 can be re-activated after air exposure at 150 °C only under hydrogen pressure. Titanium-iron (TiFe) is known to be highly sensitive to oxidation, and this impacts its use in hydrogen storage applications. To investigate the ability to control the surface oxidation of TiFe-based alloys, TiFe 0.85 Mn 0.15 was used as a base alloy due to its ease of activation and the addition of Cr investigated to facilitate its re-activation upon oxidation. Upon the formation of TiFe 0.85 Mn 0.15 Cr x (x = 0.15 and 0.30) an improvement in reactivation was observed. After exposure of TiFe 0.85 Mn 0.15 Cr 0.30 to air for 2 h, the alloy could be re-activated at 150 °C under a 3 MPa hydrogen pressure. In comparison, a temperature of 300 °C under the same hydrogen pressure was needed to re-activate TiFe 0.85 Mn 0.15. This indicates that Cr addition provided to some extent resistance against deactivation. This is also reflected in the HP-DSC measurements where a partial oxide reduction was observed at 100 °C for the oxidised TiFe 0.85 Mn 0.15 Cr 0.30 alloy as opposed to the 220 °C of TiFe 0.85 Mn 0.15. The partially reduced species acted as catalytic sites for hydrogen activation. [ABSTRACT FROM AUTHOR]

Abstract: Magnesium hydride (MgH2) with a range of morphologies has been synthesized via a simple hydrogenolysis route involving the decomposition of di-n-butylmagnesium. As the synthetic medium evolved from an inert atmosphere of argon to hydrogen pressure, the morphology shifted from rod like to small particles (25–170 nm). In cyclohexane, a solvent relative inert toward magnesium, smaller particles (15–50 nm) were formed. However in diethyl ether, which is more reactive toward magnesium, flakes organized in large microstructures were obtained. Remarkably in all cases β-MgH2 was readily obtained with some residual carbon contamination. Hydrogen release from these structures occurred at a relatively low temperature (300 °C), with desorption kinetics faster or equivalent to that of ball milled magnesium. In particular, hydrogen desorption from the smallest particles of MgH2 produced via the hydrogenolysis of di-n-butylmagnesium under hydrogen pressure or cyclohexane was impressive with the full desorption achieved in less than 10 min without any catalyst. These remarkable hydrogen storage properties are believed to result from an appropriate stabilization of the nanoparticles generated. [Copyright &y& Elsevier]

• Neat SiO 2 materials were fabricated by liquid precursor flame spray pyrolysis. • Precursor feed rate and UV light pre-treatment strongly influence oxidation performance. • Hydrogenation and UV light pre-treatment promote the formation of E′ δ center and NBOHC defect sites, respectively. • UV light pre-treatment lowers the energy barrier for oxygen activation and formic acid decomposition on the defect sites. Tailoring oxide functionalities via defect engineering is an effective approach in many advanced materials. Here we report that introducing defect sites in SiO 2 via sequential hydrogenation and UV light pre-treatment steps can invoke synergism for oxygen activation and organic dehydrogenation under ambient conditions in the absence of light. The hydrogenation step is proposed to break Si O Si bonds to give an E′ δ center – silanol pair. UV light pre-treatment then serves to dehydroxylate the silanol group to give a non-bridging oxygen hole centers (NBOHC). The two defect sites work in harmony to activate oxygen and in turn oxidize formic acid. First-principles calculations indicated that UV light pre-treatment lowered the energy barrier for oxygen activation and formic acid decomposition on the defect sites. Re-illuminating the used SiO 2 led to partial recovery of the defect sites and hence oxidation performance. The study demonstrates the capacity for generating synergistic defects in simple metal oxides as an effective way to enhance performance for oxidation processes. [ABSTRACT FROM AUTHOR]

Herein, we investigate the mechanisms involved in the selective oxidation of ethanol to acetaldehyde by localised surface plasmon resonance (LSPR) enhanced Au-Cu alloys. Temperature programmed oxidation results in tandem with quantitative in-situ DRIFTS of the surface species under different illumination conditions revealed that the cleaving of C C bonds at the Au-TiO 2 interface were inhibited in the presence of Cu at temperatures <175 °C. HAADF-STEM and XPS analysis of the spent catalysts demonstrated that the suppression of C C cleavage was due to selective electron transfer between the atomically ordered Cu and Au arrays. Thus, the selectivity of Au-Cu/TiO 2 towards the formation of acetaldehyde could be enhanced by over 800% at 100 °C under visible light illumination compared to standard thermal catalysis. Nonetheless, the selective electron charge transfer was disrupted at temperature >175 °C, lowering acetaldehyde selectivity. The work suggests that LSPR photo-enhancement is defined by the inherent electronic interactions within the bimetallic alloy and is facilitated by atomically ordering of the Au-Cu arrays. As such, in addition to performance enhancement, LSPR photo-enhancement can be used in combination with other characterisation techniques to ascertain the selective electronic pathways in bimetallic catalysts. [ABSTRACT FROM AUTHOR]

LiAlH 4 is considered as a promising material for solid state hydrogen storage. However, the lack of reversibility along with sluggish kinetics hinders its practical application. In this paper, hollow carbon nanospheres (HCNs) were used as a porous scaffold to confine LiAlH 4 via solvent impregnation method. Nanoconfined LiAlH 4 (LiAlH 4 @HCNs) exhibited significant improvements in hydrogen sorption compared to its bulk counterpart. LiAlH 4 @HCNs releases hydrogen sharply at 146 °C with full conversion to LiH within 1.5 h. The desorbed material can also be regenerated back to some extent into LiAlH 4 under 8 MPa H 2 at 150 °C. Measurement of the pressure-composition isotherm suggests an alteration in the equilibrium state upon confinement of LiAlH 4 in voids of a few nanometres and thus altered hydrogen thermodynamic paths. [Display omitted] • LiAlH 4 was confined within hollow carbon spheres by solvent impregnation method. • Nanoconfined LiAlH 4 sharpy released hydrogen at 146 °C. • Rehydrogenation was observed under moderate conditions of 8 MPa H 2 and 150 °C. • The plateau pressure corresponding to each decomposition step was not observed due to an alteration of LiAlH 4 thermodynamics. [ABSTRACT FROM AUTHOR]

The metal-hydrogen interaction and its equilibrium conditions allow for distinct properties in metal hydrides (MHs). Based on these properties, MHs have been found to enable a range of novel technologies from thermal compression to sensors, and catalysis. Ni-MH batteries are currently the main application of hydrides in the market. However, new battery concepts such as Li-MgH 2 , Mn-MH, and hydride-based solid electrolytes have emerged. Fuel cells based on hydrides have also been proposed to convert the chemical "hydride energy" into electrical energy. Based on their unique thermodynamic properties, MHs are also the basis of new concepts in hydrogen compression, heat pumps, cooling systems, and thermal energy storage. Other important applications, including catalysis and chemical speciation have also been considered owing the chemical properties of hydrides. Sensors and smart mirrors based on the dynamic optical, structural, and electrical properties of MHs have been developed. This review summarizes current state-of-the-art along the multiple applications of MHs and provides recommendations on the future progress required to enable a more widespread adoption of MHs beyond their use as hydrogen storage materials. [Display omitted] • Hydrides have a broad range of applications. • Enabling alternative applications beyond hydrogen storage could help in finally enabling the commercialization of hydrides. • The continuous development of new hydrides materials remains a critical enabler. [ABSTRACT FROM AUTHOR]

Magnesium hydride (MgH 2 ) nanoparticles have been synthesized in the presence of MoS 2 via a simple hydrogenolysis route, involving the decomposition of di-n-butylmagnesium. Remarkably using delaminated MoS 2 instead of bulk MoS 2 led to the formation of magnesium worm-like structures, which collapsed and recrystallized to some extent upon hydrogen cycling. Hydrogen release from these structures occurred at a relatively low temperature (300 °C), and MoS 2 was found to effectively improve the hydrogen desorption kinetics of nanosized MgH 2 . It took less than 150 min to fully release hydrogen from MgH 2 catalyzed by delaminated MoS 2 . In comparison, uncatalysed nanosized MgH 2 particles required more than 300 min. Furthermore, MoS 2 was found to significantly influence the thermodynamic properties of the Mg/MgH 2 reaction, via the destabilization of the Mg–H bond. Compared to ball-milled MgH 2 , the MoS 2 modified materials showed significantly higher hydrogen absorption plateau pressures (∼0.15 MPa). This demonstrates that pathways enabling the tuning of the hydrogen storage properties of nanosized MgH 2 toward lower temperatures and fast kinetics may exist. [ABSTRACT FROM AUTHOR]

Abstract: Nano-sized spinel LiMn2O4 powder with high crystallinity was prepared by a modified dynamic hydrothermal route. The as-synthesized LiMn2O4 powder exhibited high phase purity and better electrochemical properties than the material obtained via the static hydrothermal synthetic route. The dynamic method is believed to promote the simultaneous nucleation and growth of the LiMn2O4 phase during the synthesis. [Copyright &y& Elsevier]

Abstract: Ce-doped compounds Li3V2−x Ce x (PO4)3/C (x =0, 0.03, 0.05, 0.07, 0.10) were successfully prepared by a sol–gel process with CH3COOLi·2H2O, NH4VO3, NH4H2PO4, citric acid and Ce(CH3COO)3·5H2O as raw materials. X-ray diffraction analysis suggests that single-phase Li3V2−x Ce x (PO4)3/C with monoclinic structure can be obtained for x ≤0.10. The result of Rietveld refinement analysis indicates that cell volume increases with the increasing of the Ce content. As compared with the pure Li3V2(PO4)3, although there is a small decrease in the initial specific capacity at low rate (0.2C), a proper amount of Ce3+ doping, e.g. x =0.05, could improve its cycle and rate performances. When discharge at 0.2C and 10C, the initial specific discharge capacities of Li3V1.95Ce0.05(PO4)3 were 120 and 88.6mAhg−1 respectively. Furthermore, the capacity retention at the 100th cycle was 96.8% and 94.3% for the respective discharge capacities, which displayed excellent cycling properties. [Copyright &y& Elsevier]

Orthorhombic LiMnO 2 (o-LiMnO 2) is considered as a potential cathode material for lithium ion batteries due to its high theoretical capacity and low cost. However, the irreversible phase transformation to spinel LiMn 2 O 4 and sluggish lithium ion diffusion kinetics result in low practical specific capacity and poor cycling stability. In this work, conductive o-LiMnO 2 /carbon nanotubes (CNTs) composites frameworks were constructed via an ingenious one-step dynamic hydrothermal method. The obtained o-LiMnO 2 /CNTs composites achieved outstanding electrochemical performance upon adjustment of the CNTs content. The results demonstrated either physical introduction of 1 wt% CNTs into o-LiMnO 2 or in-situ formed o-LiMnO 2 /CNTs composite with 0.5 wt% CNTs could improve electrochemical performance effectively compared with pristine o-LiMnO 2. However, when the content of CNTs increased to 1 wt% in in-situ formed o-LiMnO 2 /CNTs, the specific capacity reached 194.4 mAh g−1 and retention rate was 93.7% after 50 cycles at 0.1C. Moreover, the in-situ formed composite with 5 wt% CNTs led to the optimum specific capacity of 204.9 mAh g−1 and a high capacity retention rate (97.7% after 50 cycles at 0.1C). Galvanostatic intermittent titration technique (GITT) measurement also demonstrated that 5 wt% CNTs in o-LiMnO 2 /CNTs composite drastically improved the slowest Li+ diffusion step by a factor 100 times after 30 cycles as compared to the pristine counterpart. This behaviour demonstrated an accelerated diffusion of lithium through this new approach and improved reversibility of charging-discharging. • Orthorhombic LiMnO 2 /carbon nanotubes (CNTs) nanocomposites networks were prepared via dynamic hydrothermal route. • The composite with 5 wt% CNTs delivered specific capacity of 204.9 mAh g-1 and 97.7% retention rate after 50 cycles. • GITT demonstrated the in-situ formed CNTs framework significantly improved lithium diffusion coefficient of o-LiMnO 2. [ABSTRACT FROM AUTHOR]

The thermochemical energy storage properties of calcium hydride (CaH 2) destabilised with either silicon (Si) or Ca x Si y compounds at various molar ratios, were thoroughly studied by a combination of experimental and computer assisted thermodynamic calculations. Particularly, the destabilisation effect of Si on CaH 2 at five different molar ratios (1:1, 1:2, 2:1, 3:4, 5:3 CaH 2 to Si) was extensively investigated. Theoretical calculations predicted a multi-step thermal decomposition reaction between CaH 2 and Si forming Ca x Si y at varying temperatures, which was confirmed by in-situ synchrotron X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and mass-spectroscopic measurements. The most suitable destabilisation reactions between CaH 2 and Si or Ca x Si y that meet the criteria of a thermal energy storage system for the next-generation of concentrated solar power (CSP) plants were identified. The CaH 2 and CaSi system (in a 2:3 molar ratio of CaH 2 to CaSi) showed desirable operating conditions with a decomposition temperature of 747 ± 33 °C at a hydrogen pressure of 1 bar. Pressure composition isothermal measurements were conducted on this system to determine its practical enthalpy of decomposition to form Ca 5 Si 3. The calculated value (107.3 kJ mol−1 H 2) was lower compared to the experimentally determined value (154 ± 4 kJ mol−1 H 2). This mismatch was mainly due to the formation of CaO and a CaSi solid solution in addition to the desired Ca 5 Si 3 phase. ga1 • Calcium hydride has been thermodynamically destabilised with silicon. • A multistep decomposition pathway was determined by theoretical calculations. • The experimental thermal decomposition pathway and thermodynamics were established. • The Ca–Si system is a viable thermal energy storage material. [ABSTRACT FROM AUTHOR]

CaH 2 is a metal hydride with a high energy density that decomposes around 1100 °C at 1 bar of H 2 pressure. Due to this high decomposition temperature, it is difficult to utilise this material as a thermal battery for the next generation of concentrated solar power plants, where the currently targeted operational temperature is between 600 and 800 °C. In this study, CaH 2 has been mixed with calcium halide salts (CaCl 2 , CaBr 2 and CaI 2) and annealed at 450 °C under 100 bar of H 2 pressure to form CaHCl, CaHBr and CaHI. These hydride-halide salts incur a thermodynamic destabilisation of their hydrogen release, compared to CaH 2 , so that they can operate between 600 and 800 °C within practical operating pressures (1–10 bar H 2) for thermochemical energy storage. The as-synthesised metal hydrides were studied by in-situ synchrotron X-ray diffraction, temperature programmed desorption and pseudo pressure composition isothermal analysis. Each of the calcium hydride-halide salts decomposed to form calcium metal and a calcium halide salt after hydrogen release. In comparison to pure CaH 2, their decomposition reactions were faster when heated up to 850 °C, and the experimental values of the desorbed hydrogen gas were very close to the theoretical ones. All samples after their decomposition showed signs of sintering, which hindered their rehydrogenation reaction. • CaH 2 was thermodynamically destabilised when mixed with calcium halide salts. • The new compounds exhibited faster reaction kinetics compared to CaH 2. • All three compounds exhibited equilibrium pressures between 1 and 10 bar at 650 °C. [ABSTRACT FROM AUTHOR]

• CO conversion of >98% was achieved from ∼230 °C using pristine MWCNT as a catalyst. • COOH-modified MWCNT adsorbed significant amounts of CO molecules without converting. • Cu 6 clusters initially formed CuCO 3 that decomposed above 400 °C to release CO 2. An inhibition of CO oxidation on catalytically active pristine multi-walled carbon nanotubes (MWCNT) in the presence of selected pollutant constituents in flue gas streams was studied. We simulated an interaction between the active MWCNT and the contaminants in CO oxidation atmosphere of: (i) an acidic wet flue gas environment modelled by using MWCNT grafted with carboxyl (COOH) groups; and (ii) a polluted environment formed by trace metal copper particles and other contaminant constituents (e.g. PAHs, VOCs and P) by using a copper cluster of chemical formulae [(PPh 3)CuH] 6 ·0.75THF as a model pollutant, doped on the MWCNT. The pristine, unmodified MWCNT were catalytically active from ∼150 °C, whilst the carboxyl-modified MWCNT behaved as an adsorbent of CO molecules without converting them into CO 2. The copper cluster was found to have formed CuCO 3 during the CO oxidation reaction at temperatures below 330 °C but decomposed above 400 °C to release CO 2 product. [ABSTRACT FROM AUTHOR]

The research on the functional properties of medium- and high-entropy alloys (MEAs and HEAs) has been in the spotlight recently. Many significant discoveries have been made lately in hydrogen-based economy-related research where these alloys may be utilized in all of its key sectors: water electrolysis, hydrogen storage, and fuel cell applications. Despite the rapid development of MEAs and HEAs with the ability to reversibly absorb hydrogen, the research is limited to transition-metal-based alloys that crystallize in body-centered cubic solid solution or Laves phase structures. To date, no study has been devoted to the hydrogenation of rare-earth-element (REE)-based MEAs or HEAs, as well as to the alloys crystallizing in face-centered-cubic (FCC) or hexagonal-close-packed structures. Here, we elucidate the formation and hydrogen storage properties of REE-based ScYNdGd MEA. More specifically, we present the astounding stabilization of the single-phase FCC structure induced by the hydrogen absorption process. Moreover, the measured unprecedented high storage capacity of 2.5 H/M has been observed after hydrogenation conducted under mild conditions that proceeded without any phase transformation in the material. The studied MEA can be facilely activated, even after a long passivation time. The results of complementary measurements showed that the hydrogen desorption process proceeds in two steps. In the first, hydrogen is released from octahedral interstitial sites at relatively low temperatures. In the second, high-temperature process, it is associated with the desorption of hydrogen atoms stored in tetrahedral sites. The presented results may impact future research of a novel group of REE-based MEAs and HEAs with adaptable hydrogen storage properties and a broad scope of possible applications.

Fuel cells rely on an effective distribution of the reactant gases and removal of the byproduct, that is, water. In this context, bipolar plates are the critical component for the effective management of these fluids, as these dictate to some extent the overall performance of polymer electrolyte membrane fuel cells (PEMFCs). Better bipolar plates can lead to a significant reduction in size, cost, and weight of fuel cells. Herein, we report on the use of photoresin 3D printing to fabricate alternative bipolar plates for operating self-breathing fuel cell stacks. The resulting stack made of 12 self-breathing PEMFCs achieved a power density of 0.3 W/cm 2 under ambient conditions (25°C and 20% relative humidity), which is superior to the performance of previously reported self-breathing cells. The problems associated with hydrogen leaks and water flooding could be resolved by taking advantage of 3D printing to precisely fabricate monoblock shapes. The approach of 3D printing reported in this study demonstrates a new path in fuel cell manufacturing for small and portable applications where an important reduction in size and cost is important., Competing Interests: No competing financial interests exist., (Copyright 2024, Mary Ann Liebert, Inc., publishers.)