Hydrogen storage remains a central bottleneck for scalable hydrogen energy systems due to the multiscale and coupled nature of the thermodynamics, kinetics, and microstructural evolution of hydrogen storage materials (HSMs). Although artificial intelligence (AI) has accelerated materials discovery, current approaches remain constrained by fragmented data, limited physical consistency, and weak integration with experimental validation. Here, we propose a unified framework that integrates coherent data infrastructure, physics-grounded modeling, and AI-driven inverse design within a closed-loop discovery paradigm. By embedding physical constraints and experimental feedback, this approach enables adaptive, physically consistent optimization, thereby establishing a pathway toward autonomous, digital-twin-enabled discovery of HSMs.

The chemistry of hydrogen and its interaction with matter is remarkably diverse with new discoveries and materials continuously being uncovered. New types of chemical bonding and interactions allow for the preparation of new compounds with unusual compositions and properties. For instance, neutral hydrogen molecules may spontaneously form penta-dihydrogen clusters, (H2)5, in nanoporous materials with extremely dense packing, similar to metallic hydrogen at high pressure. Hydrides with extreme hydrogen densities - 'superhydrides' - have yielded record critical temperatures under pressure and now guide routes toward low-pressure high-temperature hydride superconductors. A well-known weak interaction identified in biological matter, the hydrogen bond, has an inorganic analogue: the dihydrogen bond. These two interactions have very similar bond lengths and bond strengths that are known to produce flexible and relatively open structures, which often have interesting functionalities. Recently, the di-hydrogen bond has come into focus for development of fast divalent magnesium and calcium cationic conductors. In this review, we highlight key advances in the synthesis and characterisation of novel hydrogen-based materials and illustrate how the compositional and structural versatility of hydrides leads to new functionalities. Hydrides are highly relevant materials with a diversity of energy applications such as solid-state hydrogen storage, solid-state batteries and superconductors, as well as future global hydrogen transportation.

Mechanochemistry is emerging as a sustainable alternative to solvent-based synthesis, yet its environmental and process-scale performance for pharmaceutical applications remains underexplored. This work assesses the environmental sustainability and process efficiency of mechanochemical versus conventional solution-based routes for producing rac-ibuprofen-nicotinamide (rac-IBU:NIC) co-crystals, a model pharmaceutical solid form. Experimental data from kilogram-scale eccentric vibrating milling (EVM), attritor mill (AM) and hammer mill (HM) were integrated with process modeling, green chemistry metrics, and cradle-to-gate life cycle assessment (LCA). Mechanochemical performance in batch (EVM, AM and HM) and continuous configurations (hot melt extrusion, HME) was benchmarked against an ethanol-based crystallization process representative of current industrial practice. Green metrics results confirmed that all mechanochemical routes achieved lowest aggregate scores, outperforming the solvent-batch process, demonstrating superior greenness due to solvent elimination, high atom economy, and ambient operation. LCA results, however, indicated higher global warming and fossil resource impacts for some mechanochemical systems compared to the solvent-batch process under fossil-based electricity, reflecting their reliance on electrical power. Scenario analyses revealed that renewable electricity dramatically lowers these impacts, reducing the global warming potential of EVM by more than 90 % and rendering both EVM and HME environmentally competitive with the solvent-batch process, even when considering a green solvent such as bio-ethanol. Mechanochemistry not only eliminates solvent use but also aligns with the global transition to renewable energy, since its impacts scale directly with the cleanliness of the electricity supply, positioning it as a viable pathway toward greener pharmaceutical manufacturing.

Hydrogen has the highest gravimetric energy density of any energy carrier and it can operate in a closed cycle with no carbon emissions. Hydrogen-based materials play a critical part in hydrogen storage and helped to power the first generation of hybrid electric vehicles. In this Review, we examine several clean-energy applications of hydrogen-based materials. A major focus of research is hydrogen storage and transportation. Storing hydrogen gas is challenging, but physisorption by nanoporous materials, absorption by metal and complex hydrides, and liquid hydrogen carriers offer viable solutions for safe and economical hydrogen storage. For many applications in a future hydrogen economy, hydrogen gas must be compressed and metal hydride compressors can achieve the pressures required by the type IV compressed-gas storage tanks used in the first generation of commercial fuel cell vehicles. Hydrides are still relevant for battery technology, including as electrodes in the next generation of nickel-metal hydride batteries, as electrolytes in future solid-state batteries, or as liquid electrolytes in new battery types. Hydrides also show promise as thermal energy storage materials for the utilization of industrial waste heat and for renewable energy sources such as solar thermal power plants. We review the status of each of these technologies, which are at varying stages of implementation, providing a basis for future research on hydrogen-based materials for energy storage and conversion. Hydrogen-based materials could have various applications across energy technologies. This Review discusses the use of these materials in energy storage and in hydrogen storage, transportation and compression.

This study focuses on optimizing the synthesis of a few-layer graphene-encapsulated iron-based nanoparticles (Fe/Fe3C@C), prepared through spray drying, chemical vapor deposition (CVD), and leaching processes using ferrocene-based precursors, and their application as nanocatalysts for hydrogen (H2) production via sodium borohydride (NaBH4) methanolysis. Ferrocene-impregnated silica powders were prepared by spray drying them from a solution containing ferrocene, fumed silica, and ethanol. Then, these prepared powders, known as precursor powders, were subsequently introduced into the CVD system. Both the reduction of ferrocene and the encapsulation of Fe-based nanoparticles by graphene layers occurred in-situ during the CVD process. CVD temperature and the flow rates of CH4 and H2 gases are critical parameters that effects of the microstructural, thermal, and magnetic properties of synthesized nanoparticles. The CVD system was performed at temperatures ranging from 850 to 1000 degrees C, with variable gas flow rates of 50 or 100 mL/min. Additionally, acid leaching with hydrofluoric (HF) and hydrochloric (HCl) acids ensured the synthesis of pure powders free from silica and uncoated Fe, confirming the chemical stability of the nanoparticles. The presence of graphene in all synthesized samples within these parameter ranges were confirmed by Raman spectroscopy. Phase identifications were carried out using X-ray diffraction (XRD) and Mo & uml;ssbauer spectroscopy, revealing the Fe and trace amount Fe3C as core phases. Transmission electron microscopy (TEM) revealed the core-shell structure of the nanoparticles with a few layers of graphene coatings. Based on the coercivity and magnetic saturation values obtained from vibrating sample magnetometry (VSM), synthesized core-shell nanoparticles exhibited soft magnetic properties (Ms = 22.4-33.5 emu/g, Hc = 82.3-278.3 Oe). Fe/Fe3C@C nanoparticles obtained under optimum conditions achieved very high H2 production rate (HPR = 54200 mLH2 gcat h- 1) values, with low activation energy (Ea = 20.08 kJ mol- 1) value, highlighting their potential as an efficient and promising candidate catalyst for industrial-scale H2 production via the NaBH4 methanolysis reaction. In addition, it was found that the Fe/Fe3C@C nanoparticles retained 48% and 71% of their initial activity after 5 consecutive cycles, as measured by the HPR and TOF values, respectively.

Natural hydrogen, or "white hydrogen," is a promising low-cost, low emission, yet abundant form of hydrogen. The redox reaction between water and iron(II) species in minerals such as olivine is considered the most important process (e.g., serpentinization) to generate natural hydrogen. Instead of at high temperatures or pressures, this work presents the possibility of the reaction via only mechanical energy input.

Mechanochemical cocrystallization provides an efficient, solvent-minimized route for the production of pharmaceutical cocrystals. Although the small-scale synthesis of cocrystals is well established, strategies for the gradual scale-up to multigram and kilogram quantities remain limited. By systematically analyzing and comparing different scale-up stages, this study investigates the scale-up of paracetamol-oxalic acid (PCA-OXA) cocrystals using a range of milling technologies, including planetary ball mills, attritor mill, and drum mill. We aim to provide practical guidance on the capabilities and limitations of these devices and identify suitable milling parameters and strategies that ensure complete conversion and high product quality as batch sizes increase. In practice, planetary ball mills were used to prepare multigram quantities, while attritor mills generated hundred-gram batches under dry milling conditions. At the kilogram scale, drum milling required liquid-assisted grinding (LAG) with ethyl acetate to prevent caking and achieve full conversion. The results show that the gradual scale-up of PCA-OXA cocrystals is feasible when milling conditions and appropriate milling technologies are carefully selected, maintaining high yields and product quality across different scales. The findings contribute to a better understanding of the opportunities and limitations of mechanochemistry in pharmaceutical cocrystal development and offer guidance for the transition from laboratory-scale discovery to larger-scale production.

This article presents a novel high-entropy-alloy (Ti 0.325 V 0.275 Zr 0.125 Nb 0.275 )C x with interstitial carbon that does not change its volume during hydrogen cycling.

Effective thermal conductivity (ETC) of dimagnesium nickel tetrahydride (Mg2NiH4), prepared via temperature driven cycles under hydrogen atmosphere of a 2 Mg + Ni powder mixture (activation at 350 °C, 18.4 bar of hydrogen pressure for 24 h) was measured by applying the transient plane source method. In each cycle, measurements were carried out in hydrogenated and dehydrogenated state during 310 hydrogenations and 309 dehydrogenations. Before and after activation ETC isotherms were measured from 1 bar to 90 bar H2-pressure, in a temperature range from 30 °C to 100 °C before activation and from 30 °C to 350 °C after activation. The H2-release/uptake for all cycles was calculated using the pressure increase/drop during de-/hydrogenations. The hydrogen amounts are in good correlation with TGA-DSC measurement results of the sample, taken after the test. The effective thermal conductivity of the initial powder mixture increased with temperature and pressure, varied between 0.36 Wm−1K−1 (at 1 bar, 30 °C) and 0.56 Wm−1K−1 (at 70 bar, 100 °C). During activation at 350 °C the effective thermal conductivity increased from 0.25 Wm−1K−1 to 0.46 Wm−1K−1 while pressure in the whole set-up decreased by 6.5 bar due to hydrogenation. Varying ETC and dehydrogenation pressures over the first 70 cycles gave hint to a formation of Mg2NiH4/Mg2Ni from 2 MgH2 + Ni/2 Mg + Ni + 2 H2. XRD measurements before and after activation of an equally treated sample and of the cycled sample after the tests’ end support those findings.

Abstract Energetic materials, mainly propellants, explosives, and pyrotechnics, are crucial in various civilian applications, such as fuels for rockets and spacecraft. Current energetic fuels rely on highly toxic and polluting ammonium perchlorate (AP) or carcinogenic hydrazine derivatives, encouraging the search for greener and safer substitutes. This work demonstrates the first use of amine‐AlH 3 adducts as potential solid fuels with promising hypergolic properties, high energy content, and without toxic derivatives. The herein presented four amine‐AlH 3 adducts, AlH 3 coordinated with quinuclidine (Quin), triethylenediamine (TEDA), hexamethylenetetramine (HMTA), and tetraazatricyclododecane (TATD), illustrate a unique strategy to create new solid fuels by combining AlH 3 with an energy‐rich nitrogen‐containing molecule. The crystal structures of new compounds ([HMTA‐AlH 3 ] n and [TATD‐AlH 3 ] n ) are determined from powder X‐ray diffraction data. Differential scanning calorimetry‐thermogravimetric analysis (DSC‐TGA) of the samples combined with mass spectrometry (MS) evidence high thermal stability. The ultrashort ignition delays as low as one ms show an excellent hypergolic response. Four amine‐AlH 3 adducts have higher combustion heat (> 29 kJ g −1 ) than conventional hydrazine fuels (19.5 kJ g −1 ). Finally, the successful mechanochemical syntheses of Quin 2 AlH 3 and [HMTA‐AlH 3 ] n are introduced, showcasing a green chemistry approach to energetic materials.

Correction for ‘Utilizing an attritor mill for solvent-free mechanochemical synthesis of rac -ibuprofen:nicotinamide co-crystals’ by Sarah Triller et al. , RSC Mechanochem. , 2025, 2 , 538–543, https://doi.org/10.1039/D5MR00020C.

A solvent-free mechanochemical method for the catalytic hydrogenation of nitro compounds is reported, requiring only the substrate, low catalyst loading, and molecular hydrogen. The approach avoids the use of additional base additives or solvents for liquid-assisted grinding. The transformation proceeds under mild conditions using palladium on carbon and hydrogen gas in pressurizable stainless steel jars operated in a planetary ball mill. A variety of functionalized nitro compounds are converted to the corresponding anilines and amines in good to excellent yields. The method displays chemoselectivity, tolerating functional groups such as halogens, benzylic ketones, and nitriles. In addition, scale-up to multigram quantities is achieved, and an analysis of trace metal impurities from abrasion revealed only minor concentrations, all below the limits established by ICH guidelines. The protocol's practicality is demonstrated by synthesizing intermediates and active ingredients used in pharmaceuticals and agrochemicals. To quantify the sustainability of the protocol, green metrics are calculated and compared with those of other mechanochemical and solution-phase nitro compound reduction methods.

Within pharmaceutical research and development, co-crystallization has emerged as a common strategy to modify the physicochemical properties of active pharmaceutical ingredients, tackling a wide array of challenges in drug formulation. Contrasting with conventional solution-based methods that typically consume substantial amounts of solvents and energy, we herein present a more eco-friendly and efficient mechanochemical process for producing co-crystals at kilogram scale. Our study pioneers the use of a drum mill for pharmaceutical co-crystal synthesis, using rac-ibuprofen:nicotinamide as a representative example. Our findings demonstrate the viability of repurposing common industrial milling equipment for potential large-scale production of pharmaceutical co-crystals. With the optimized system and utilizing liquid-assisted grinding techniques, the reaction was completed within 90 min and yielded 99% of pure rac-ibuprofen:nicotinamide co-crystals by simply sieving off the grinding media. Examination of the resulting co-crystals showed minimal metal contamination from abrasion, with levels well within acceptable regulatory standards for daily intake. Our findings underscore the promise of drum mill technology in creating greener processes for large-scale pharmaceutical co-crystal synthesis, paving the way for more sustainable industrial drug manufacturing practices.

Energetic materials, mainly propellants, explosives, and pyrotechnics, are crucial in various civilian applications, such as fuels for rockets and spacecraft. Current energetic fuels rely on highly toxic and polluting ammonium perchlorate (AP) or carcinogenic hydrazine derivatives, encouraging the search for greener and safer substitutes. This work demonstrates the first use of amine-AlH3 adducts as potential solid fuels with promising hypergolic properties, high energy content, and without toxic derivatives. The herein presented four amine-AlH3 adducts, AlH3 coordinated with quinuclidine (Quin), triethylenediamine (TEDA), hexamethylenetetramine (HMTA), and tetraazatricyclododecane (TATD), illustrate a unique strategy to create new solid fuels by combining AlH3 with an energy-rich nitrogen-containing molecule. The crystal structures of new compounds ([HMTA-AlH3]n and [TATD-AlH3]n) are determined from powder X-ray diffraction data. Differential scanning calorimetry-thermogravimetric analysis (DSC-TGA) of the samples combined with mass spectrometry (MS) evidence high thermal stability. The ultrashort ignition delays as low as one ms show an excellent hypergolic response. Four amine-AlH3 adducts have higher combustion heat (> 29 kJ g-1) than conventional hydrazine fuels (19.5 kJ g-1). Finally, the successful mechanochemical syntheses of Quin2AlH3 and [HMTA-AlH3]n are introduced, showcasing a green chemistry approach to energetic materials.

Over the past two decades, main group elements have gained attention as promising substitutes for precious metals in catalytic processes. Additionally, mechanochemistry is emerging as a field with the potential to promote catalytic reactions under mild conditions. Herein, we report a scalable, main-group mechanocatalytic synthesis of cyclic carbonates from both solid and liquid epoxides, using CO₂ as a renewable feedstock under mild conditions with a gallium aminotrisphenolate catalyst. Unlike solution-based methods that generally require high temperatures and/or high CO₂ pressures, this mechanocatalytic process operates at just 1 bar and room temperature. The developed mechanochemical method affords the targeted compounds in high yields while also enabling efficient transformation of multi-terminal epoxides and avoiding the conversion losses typically observed in solution. Furthermore, this scalable method outperforms solution-based approaches across all green metrics, setting a new benchmark for environmentally friendly synthesis.

Correction for ‘Mechanochemical kilogram-scale synthesis of rac -ibuprofen:nicotinamide co-crystals using a drum mill’ by Jan-Hendrik Schöbel et al. , RSC Mechanochem. , 2025, 2 , 224–229, https://doi.org/10.1039/D4MR00096J.

The co-crystal formed from the WHO essential drug rac-ibuprofen (IBU) and the food additive nicotinamide (NIC) exhibits enhanced physicochemical and analgesic properties compared to the pure active pharmaceutical ingredient (API), exemplifying how co-crystallization can modify pharmaceutical characteristics. Herein, we present a more sustainable, solvent-free mechanochemical process for synthesizing rac-ibuprofen:nicotinamide (IBU:NIC) co-crystals, moving beyond conventional solution-based methods that typically require substantial amounts of solvents and energy. For the first time, we investigate the application of a horizontal attritor mill for co-crystal synthesis. Our findings demonstrate the effectiveness of this milling technology in facilitating the co-crystallization process, achieving pure co-crystals within 30 min. Additionally, initial experiments were conducted to explore the transition from a batch process to a sequential process. While our approach demonstrate the use of attritor mills for pharmaceutical co-crystal synthesis on a multigram scale, it also indicates opportunities for scaling up this process using industrial attritor mills. This work underscores the adaptation of existing grinding technologies to facilitate mechanochemical reactions, showcasing greener alternatives for pharmaceutical manufacturing.

We reveal excellent separation of H 2 from CH 4 -rich gas mixtures by magnesium-based hydrides. Moreover, we shed light on the processes accompanying H 2 separation, discovering, among others, the formation of a networked MgH 2 microstructure.