The cyclic stability of hydrogen storage materials largely determines the service life and long-term performance retention of hydrogen storage systems. The ab−/desorption procedure of the metal-hydride-based hydrogen compressor is carried out between two temperatures. Therefore, the investigation of degradation of the hydrogen storage capacity of the alloy under temperature swinging is particularly important for compression applications. This study investigates the hydrogen storage capacity of a new AB2-type alloy (Ti, Zr)1(Mn, Cr, Cu, V, Fe)2, designed based on earth-abundant and price-stable elements, during the long-term absorption and desorption cycles under a working temperature difference range of 130 K. In particular, the specific alloy developed does not contain any Cobalt, Nickel, or other critical raw elements which increase the cost of the material. The alloy exhibits exceptional cycling stability, retaining over 99% of its initial hydrogen storage capacity after 20′000 cycles. In comparison, an AB5-type alloy investigated under the same conditions lost 26% of its initial capacity after only 3000 cycles. The AB2-type alloy maintains a stable single C14 Laves phase throughout the cycling process confirmed by XRD. The unit cell lattice parameter “a” and “c” gradually increase by 0.2%, but the c/a ratio remains during the cycles. The particle size (D50) reduces from initially 68 μm before activation to 0.58 μm after 20′000 cycles. The ratio of Zr agglomeration area fraction increases from 1.65% to 6.23% after 20′000 cycles. The kinetics results show a stable absorption kinetic during 3000 cycles, however the desorption kinetics required 1000 cycles to remain stable. The superior cycling stability of the alloy demonstrates its strong potential for practical applications in large-scale hydrogen storage and compression systems and confirms the long service life expected from such systems.

Mg-based solid-state hydrogen storage faces a fundamental materials design paradox: reconciling near theoretical hydrogen capacity with rapid sorption kinetics while maintaining economically viable material costs-a triad wherein enhancing any two properties has traditionally necessitated compromising the third. In this study, the quantitative relationship between absorption property with chemical compositions basing machine learning (ML) strategy through SHAP-based feature ranking with six algorithms: Linear Regression (LR), Decision Tree (DT), K-Nearest Neighbors (KNN), Support Vector Machine (SVM), Random Forest (RF), and Xtreme Gradient Boosting (XGBoost), and then identifying six critical descriptors (Mg/Ni content, atomic size mismatch delta, mixing entropy change Delta S, valence electron concentration VEC and electronegativity C). Their contributions are mathematically fused into a composite parameter Z, which showed a sigmoidal logistic relationship with H2 storage capacity. Crucially, Z enables rational binary doping synergistically pairing lattice-distorting and interface-catalyzing elements - to transcend performance-cost trade-offs. Guided by optimized boundaries (Mg >= 90 at.%, Ni <= 10 at.%, delta: 6.4-6.99 %, Delta S: 2.81-3.35 J/mol & sdot;K, VEC: 2.7-2.72 e/a, C: 1.356-1.368), the designed Mg89.5Ni9(CaNd)1.5 is experimentally realized, achieving 6.27 wt% H2 absorption capacity, as well as lower 200 degrees C desorption temperature. This series alloys showed 1.114 wt%/min desorption kinetics behavior (with 6.3 times faster than that of Mg-Ni alloys with high Ni content), confirming 93 % and 46 % absorption/desorption time reduction, basing JMAK model analysis. These promotions are mechanistically attributed to binary-dopinginduced alpha-Mg/Mg2Ni lattice distortion and interfacial nano-structuring, thereby resolving the capacity-kineticscost triad through atomistically informed design.

Achieving precise control over active metal dispersion in supported catalysts requires a deep mechanistic understanding of the synthesis process. In this study, we systematically dissect the individual steps of the incipient wetness impregnation (IWI) method to understand their influence on the physicochemical properties and catalytic performance of Ru/Al2O3 catalysts for CO2 methanation. By independently tuning the Ru precursor solution, drying conditions, calcination temperature, and subsequent post-calcination treatment, we isolate the effects of each parameter and reveal their mechanistic roles in controlling Ru nucleation, particle growth, and metal-support interactions. High dispersion of Ru nanoparticles (0.5-1.5 nm) was achieved at loadings of 0.5-2.5 wt%, resulting in catalysts with outstanding activity and stability. Among the examined steps, precursor concentration and solvent evaporation rate were identified as key factors governing Ru particle size and dispersion. Importantly, small Ru particles remained resistant to sintering even after calcination at 800 degrees C and long-term operation under harsh Sabatier reaction conditions, owing to strong metal-support interactions promoted by low-acidity precursor environments. Additionally, we demonstrate that residual chlorine species derived from RuCl3 & sdot;xH2O precursors strongly inhibit catalytic activity if not removed. Ammonia-assisted posttreatment effectively eliminated surface chlorine, unlocking the full activity of Ru sites. This work provides the first comprehensive mechanistic analysis of individual synthesis steps in IWI, offering a pathway for rational catalyst design and scalable production of robust, high-performance Ru-based methanation catalysts.

The cyclic stability of hydrogen storage materials largely determines the service life and long-term performance retention of hydrogen storage systems. The ab- /desorption procedure of the metal-hydride-based hydrogen compressor is carried out between two temperatures. Therefore, the investigation of degradation of the hydrogen storage capacity of the alloy under temperature swinging is particularly important for compression applications. This study investigates the hydrogen storage capacity of a new AB 2 -type alloy (Ti , Zr) 1 (Mn, Cr, Cu, V, Fe) 2 , designed based on earth-abundant and price-stable elements, during the long-term absorption and desorption cycles under a working temperature difference range of 130 K. In particular, the specific alloy developed does not contain any Cobalt, Nickel, or other critical raw elements which increase the cost of the material. The alloy exhibits exceptional cycling stability, retaining over 99% of its initial hydrogen storage capacity after 20 ' 000 cycles. In comparison, an AB 5 -type alloy investigated under the same conditions lost 26% of its initial capacity after only 3000 cycles. The AB 2 -type alloy maintains a stable single C14 Laves phase throughout the cycling process confirmed by XRD. The unit cell lattice parameter "a" and "c" gradually increase by 0.2%, but the c/a ratio remains during the cycles. The particle size (D 50 ) reduces from initially 68 mu m before activation to 0.58 mu m after 20 ' 000 cycles. The ratio of Zr agglomeration area fraction increases from 1.65% to 6.23% after 20 ' 000 cycles. The kinetics results show a stable absorption kinetic during 3000 cycles, however the desorption kinetics required 1000 cycles to remain stable. The superior cycling stability of the alloy demonstrates its strong potential for practical applications in large-scale hydrogen storage and compression systems and confirms the long service life expected from such systems.

Acidic CO2 electrolysis enables high CO2 utilization through carbonate protonation and high C2+ selectivity due to the elevated local alkalinity, yet its lifetime remains limited by gas diffusion electrode flooding. In this study, we reveal that a loosely packed, house-of-cards structure can be obtained by incorporating 2D-structured graphene nanoplatelets (GNPs) with Cu-based catalysts, effectively mitigating flooding. With an optimal GNP content below 9 wt%, this structure enhances CO2 diffusion and significantly improves electrode lifetime, reaching 10 hours at a high current density of 600 mA cm-2. Excessive GNP content leads to catalyst layer densification and accelerates flooding, highlighting the importance of a structure sufficiently thick to accommodate liquid seepage but also sufficiently porous to allow CO2 access throughout the entire thickness. Our findings provide insights into a practical microstructural strategy for developing efficient and stable CO2 electrolysis systems.

Zirconium metal-organic cages (Zr-MOCs) exhibit promising applications in adsorption and molecular separation, thanks to their high porosity, stability, and solution processability. However, their synthesis relies on traditional solvothermal methods. In this work, we developed a mechanochemical synthetic route for Zr-MOCs by milling pre-formed Zr-clusters with terephthalic acid. The Zr-3-cluster is easily prepared by combining zirconocene dichloride with carboxylic acids such as acetic acid and benzoic acid. Typical yields of 70% were achieved in only 30 minutes, using a minimal amount of DMF (eta = 0.5 & micro;L g(-1)). This kinetically controlled strategy produces phase-pure tetrahedral cages with high surface area (>450 m(2) g(-1)), comparable to those produced by conventional solvothermal processes. The method enables tunable cage architectures by varying ligand identity. The successful synthesis of Zr-MOCs with mono- and bi-functional bidentate ligands, as well as tri-dentate ligands, was achieved, demonstrating the versatility of the mechanochemical approach. This work opens new possibilities for the preparation of Zr-MOCs with insoluble ligands and facilitates scalable production.

Vanadium-based alloys possess high hydrogen storage capacities but suffer from severe cyclic decay. Herein, we demonstrate that the electronegativity difference between V and alloying elements (ΔχV-M) fundamentally governs local hydrogen distribution, thereby dictating phase evolution and cyclic stability. Specifically, alloying with Fe (ΔχV-M = −0.20) intrinsically weakens local H–metal interactions, giving rise to H-depleted regions. The resulting heterogeneous hydrogen distribution suppresses irreversible interstitial H trapping and spatially confines the phase transformation. Consequently, localized atomic rearrangement is effectively restricted, mitigating lattice mismatch and significantly reducing continuous capacity degradation. In contrast, alloying with Zr (ΔχV-M = +0.30), strengthens H–metal interactions, promotes local hydrogen enrichment, expands the phase transformation region, and accelerates cycling degradation. These findings reveal the pivotal role of electronegativity in regulating degradation behavior from an electronic-structure perspective and establish ΔχV-M as a practical design descriptor for developing highly cycle-stable hydrogen storage alloys.

In this work we present a novel hydrogen refueling station based on metal hydride combined storage and compression designed for fast refueling of standard Hyundai hydrogen trucks. The compression is achieved in two stages from 30 bar(a) to 410 bar(a) with 28 kg hydrogen capacity. The 15 min fast fueling of H2 trucks is achieved by using a thermal storage to supply a high thermal power to the high-pressure metal hydrides compression stage. The detailed design and process optimization is performed using multi objective optimization. The energy reduction achieved in the low-pressure stage is 32 % and the size of the thermal storage is reduced by almost 3 times. A control logic is presented for the fueling according to the fueling protocol limitations. The dispenser pressure is successfully maintained within the protocol pressure corridor, while maintaining both mass flow rate and temperature of hydrogen in the tank within the safety limits.

A continuous production prototype for scaling up the synthesis of a graphene oxide/multi-walled carbon nanotubes (GO/MWCNTs) composite as a hydrogen storage material has been proposed in this study. This prototype consists of an automatic feeding and mixing step wherein KMnO4 and graphite are individually fed into concentrated H2SO4 and then mixed to form a graphite/oxidant mixture. Following this, the oxidation step involves oxidizing the graphite/oxidant mixture through two-step oxidation to produce a graphene oxide dispersion. Then, the composite synthesis step includes mixing, sonicating, and stirring the graphene oxide dispersion with a sonicated dispersion of MWCNTs to obtain the final product. As a result, the morphology and structure of the GO/MWCNTs composite synthesized by the large-scale method exhibit high similarity to those of the gram-scale sample. The GO/MWCNTs exhibited a 3D nanostructure composed of MWCNTs linked to the graphene oxide layers. The hydrogen storage test results, simulated to practical hydrogen storage tanks with large amounts of adsorbents, indicated that the hydrogen storage capacity of GO/MWCNTs can reach 3.1 wt% at ambient temperature and 50 bar. The analysis of life cycle impacts in terms of energy consumption, carbon footprint, cost, and environmental impact indicated that the proposed large-scale continuous production prototype is greener compared to other methods. Therefore, this approach holds great potential for industrial applications, paving the way for commercialization and facilitating the development of small storage units to explore the properties of the new storage system.

One of the leading approaches to enhancing the performance and stability of perovskite solar cells (PSCs) involves passivating the perovskite surface and grain boundaries with large ammonium salts. Here, we report the synthesis of furan-, thiophene-, and selenophene-functionalized phenyl methanaminium iodide salts (FPMAI, TPMAI, and SPMAI) and their application as passivating agents on 3D [(Cs0.04FA0.85MA0.11)Pb(I0.96Br0.01Cl0.03)3] perovskite. The TPMAI-passivated PSCs performed the best and achieved a power conversion efficiency (PCE) of 23.15% compared to the reference (without a passivating agent) at 20.91%. Efficiencies reduced to 98 and 54% of the initial value after 1250 h of continuous illumination for TPMAI-treated PSCs and the reference, respectively. DFT calculations revealed that TPMAI offers superior passivation, disfavoring iodine vacancy formation. Our findings highlight the potential of functionalized PMAI salts as passivation agents for improved efficiency and stability in PSCs.

Catalytic hydrogen combustion (CHC) plays a crucial role in enhancing the safety and efficiency of fuel cells and electrolysers, thereby promoting the H2 economy. To increase the catalytic activity of supported metal particles for CHC, the active surface area can be increased through Ru fine dispersion, and intrinsic activity can be enhanced by optimising metal-support interactions (MSIs). In this study, we report the synthesis and CHC performance of highly dispersed Ru sub-nanoparticles on a gamma Al2O3 support with various Ru loadings. A clear correlation between Ru loading and CHC mass activity was identified. The highest mass activity is achieved at 1 wt% Ru, with a yield of 5.7 mmolH2 mol-1Ru s-1 at 80 degrees C. Lower Ru loadings lead to a strong MSI and subsequently to a lower Ru0/Ru-O ratio. Further, higher Ru loadings decrease metal dispersion, reducing CHC activity. Operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations confirmed the role of OH groups as key intermediates in the CHC mechanism over the Ru-gamma Al2O3 catalyst. Our findings highlight the impact of Ru nanoparticle size engineering on CHC mass activity and provide mechanistic insights and design principles for the development of highly active Ru catalysts, showing a way forward to achieve safer, integrated and efficient CHC utilisation.

Hydrogen storage materials store hydrogen in their atomic states, enabling more compact and safer storage methods compared to those for gaseous and liquid hydrogen. Although various types of hydrogen storage materials have been reported, new materials with higher hydrogen storage capacities and enhanced durability are required. Herein, we report the synthesis, crystal structure, and hydrogen storage properties of an AB3-based alloy, Y0.68Mg0.32Co3.00, which exhibited reversible hydrogen absorption and desorption with a hydrogen storage capacity of 1.68 mass % and minimal degradation over 100 cycles at 303 K. The hydrogen storage capacity of Y0.68Mg0.32Co3.00 exceeds that of LaNi5, a reported hydrogen storage material with 1.38 mass %. It further increased to 2.88 mass % at room temperature under 10 GPa. This finding suggests that Y0.68Mg0.32Co3.00 has the potential for even greater hydrogen storage capacity. This could lead to more compact and lightweight storage solutions for hydrogen energy devices.

Direct light olefin synthesis from CO2 hydrogenation is a new pathway to decarbonize the chemical industry. Inspired by the promising catalytic activity of Ga2O3-based catalysts in alkane dehydrogenation, this study reveals that optimizing Ga content in the GaxIn2-xO3/SSZ-13 catalytic system can narrow the product distribution toward light olefins. The optimized catalyst exhibits light olefin and C2H4 selectivity up to 84 % and 45.9 %, respectively, amongst C2+ hydrocarbons with a maximum olefin/paraffin ratio of 6.4 and a CO2 conversion of 14.8 % at 20 bar and 653 K. In particular, a sevenfold increase in C2H4 space-time yield compared to pure metal oxides on SSZ-13 was observed, along with the gradual suppression of C3H8 formation. Herein, we established a catalyst structure-performance relationship as a function of chemical composition. As such, CO and paraffin formation rates can be suppressed, and light olefin formation rates can be enhanced. Therefore, the change in light olefin STY upon gallium incorporation could be ascribed to modulations in the structural and electronic properties, as well as alterations in the surface adsorption and acidic strengths. The findings presented here provide a strategy to tune CO2 hydrogenation product distributions toward specific target products.

Accurate evaluation and comparison of site-normalized catalytic activity (turnover frequency, TOF) in heterogeneous catalysis require consideration of catalyst nanoparticle (NP) size and geometry. In this study, we systematically quantify the impact of NP geometry on the fraction of surface atoms across FCC, BCC, and HCP crystal structures with various geometries and evaluate the absolute and relative errors introduced by assuming spherical NPs. Using catalytic H2 combustion (CHC) over an octahedron Ni catalyst supported on γAl2O3 as a model experiment, we demonstrate that assuming spherical single-crystal Ni NPs underestimates the fraction of the surface atoms and overestimates TOF by 86%. This discrepancy arises from the miscalculation of surface site availability in spherical approximations. These findings emphasize the need for geometry-specific models to ensure reliable TOF calculations and accurate catalyst performance comparisons in heterogeneous catalysis. We work provide a framework for geometry-dependent TOF calculations, offering new insights into morphology-controlled catalyst design and facet-specific reactivity optimization.

Acidic environments enhance CO2 utilization during CO2 electrolysis via a buffering effect that converts carbonates formed at the electrode surface back into CO2. Nevertheless, further investigation into acidic CO2 electrolysis is required to improve its selectivity towards certain CO2 reduction reaction (CO2RR) products, such as multicarbon (C2+) species, while enhancing its overall stability. In this study, liquid product recirculation in the catholyte and local OH- accumulation were identified as primary factors contributing to the degradation of gas diffusion electrodes mounted in closed-loop catholyte configurations. We demonstrate that a single-pass catholyte configuration prevents liquid product recirculation and maintains a continuous flow of acidic-pH catholyte throughout the reaction while using the same volume as a closed-loop setup. This approach improves electrode durability and maintains a Faradaic efficiency of 67% for multicarbon products over 4 h of CO2 electrolysis at -600 mA cm-2.

Catalytic H2 combustion (CHC) is an efficient way to mitigate H2 slip from industrial processes, overcoming the explosion and NOx emission risks. Although Pt-based catalysts are state-of-the-art catalysts, little is known about the CHC catalytic activity of other transition metals (TMs) and their reaction kinetics. Well-dispersed nano-sized M-gamma Al2O3 (M = Pt, Ru, Co, Ni, Mo) catalysts are synthesized and characterized with spectroscopic and electron microscopy methods. During the CHC reaction, a competitive reaction between O2, H2 and the catalyst is observed, which leads to partial or complete oxidation of the TMs. Stable CHC performance is attained for Ru gamma Al2O3 and Co-gamma Al2O3 catalysts over 45 h. The kinetically controlled region is determined using a new data acquisition approach. The activation energy and pre-exponential factor are compared between M-gamma Al2O3 catalysts based on the Arrhenius model. This knowledge is highly valued and allows the design of supported catalysts and optimize the CHC reaction in various applications with different requirements.

In situ investigation of the surface composition of catalyst particles improves the understanding of the active species in heterogeneous catalysis. This study analyzed the surface chemistry of ruthenium nanoparticles supported on alumina during CO2 methanation. A model ruthenium catalyst was synthesized via DC magnetron sputtering and depositing the size selected 3.3 nm Ru-particles on an Al2O3 sample. The sample was transferred into the analyzing chamber under UHV conditions and analyzed using NAP-XPS. The emitted photoelectrons show that the main oxidation state of Ru after the deposition is RuOx, transient surface oxide. In vacuum, increasing temperature resulted in the reduction of Ru to its metallic state. The hydrogen presence in the methanation feed lowered the temperature required for the reduction from 200 degrees C to 100 degrees C. In contrast, the temperature of reduction of RuOx under CO2 atmosphere increased from 200 degrees C to 300 degrees C as CO2 is a mild oxidant. The reaction intermediates of the CO2 reduction at 350 degrees C consist of C-C and C-H bonds, whereas the absence of H2 leads to the formation of C=C bonds on the surface. The Ru particle size on alumina was investigated by TEM and size stability under reactive conditions was observed over the in-situ experimental timescale of hours.

Deep eutectic solvents (DESs) are novel mixtures that exhibit a significant depression in melting points compared to their individual components. This work finds that combining tetrabutylammonium borohydride (TBABH) with ammonia borane (AB) yields new, stable, hydrogen-rich liquids under ambient conditions, with a glass transition as low as -50 °C. Liquid mixtures containing up to 6.9 wt% hydrogen can be easily obtained through physical grinding. The strong interaction between the BH4 - anion of TBABH and AB coupled with the vibration dynamics of the alkyl chains accounts for the sharp decrease in melting point. The eutectic point is identified at a TBABH-AB molar ratio of 1-2. Increasing the AB ratio further reduces the glass transition temperature but also induces a cold crystallization phenomenon. These mixtures can release hydrogen at temperatures as low as 60 °C, making them promising candidates for hydrogen storage. This represents the first example of a hydride-based DES, advancing research on complex hydrides and opening the door to the discovery of new hydrogen-rich liquids for various applications.

The catalyst-free CO2 reduction with ammonia borane in the solid state is reported. Close to 40 mmol of CO2 per gram of ammonia borane can be reduced at 0.5 MPa and 60 °C to formamide in high yield, achieving a highly atom-economical process.