Ammonia synthesis under mild conditions remains a long-standing grand challenge due to the kinetically stable N2 and thermodynamically unstable NH3. Here we report a V–LiH composite catalyst for efficient photo-driven ammonia synthesis under UV-Vis irradiation. Vanadium incorporation extends the light absorption of LiH into the visible–near-infrared region, increases the surface area, and promotes the generation of electron‑rich hydrogen vacancies at the V–LiH interface. The optimal V–5LiH composite achieves an ammonia production rate of 1945 μmol g−1 h−1 at 623 K under broadband illumination with a low intensity of 0.60 W cm−2. Temperature‑compensated ammonia synthesis experiments reveal a photoexcitation contribution beyond photothermal heating, which lowers the apparent activation energy from 62.3 kJ mol−1 (dark condition) to 37.3 kJ mol−1 (light irradiation). This work offers a promising strategy for constructing transition-metal/hydride interfaces toward photo-driven ammonia synthesis.

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.

Potassium (K) has long been employed as a key catalyst promoter for ammonia synthesis. Its chemical state and promoting mechanism, however, remain elusive. Here, we study the influence of different anionic counterparts of K (i.e., H− and OH−) on its promoting capability and function in ammonia synthesis catalysis. When potassium is in the form of hydride (KH), it can enhance the ammonia formation rate of the Fe/carbon nanotube (CNT) catalyst by two orders of magnitude; while it is in the form of hydroxide (KOH), the rate increment is only ∼5 times. We show that both KH and KOH can promote N removal from Fe nitride under a hydrogen atmosphere, where an intermediate KNH2 species may form and further be hydrogenated to NH3. Isotopic measurements show that H atoms in KH and KOH are involved in the formation of NH3. For the KH-Fe catalyst, the hydridic H of KH is reductive and may undergo a redox reaction with adsorbed N (Nad) on Fe to form KNHx species and further be hydrogenated to NH3 and create a clean Fe surface for further nitrogen activation. For the KOH-Fe catalyst, the protonic H of KOH may protonate Nad on Fe to form NH3 through the intermediate species of K–Fe–O and KNH2. This work reveals the crucial role of hydrogen in ammonia synthesis catalysis and, moreover, could inspire revisiting of the role of alkali promoters in industrial ammonia synthesis catalysts.

The activation and valorization of inert molecules (e.g., dinitrogen (N2), alkanes, and alkenes) for the synthesis of nitrogen-containing organic compounds have long been a highly sought-after goal in chemistry. However, it remains a formidable challenge, stemming from the inherent chemical inertness of the robust N ≡ N and C-H bonds, as well as the competitive adsorption and activation of reactants. Consequently, examples of direct C-N bond formation using N2 and alkanes/alkenes as feedstocks remain exceptionally scarce. Herein, we report that sodium hydride supported on magnesium oxide (NaH/MgO) possesses unique multiple reactive sites, which enable the conversion of N2 and unactivated arenes and facilitate C-N bond formation. The synergistic interplay between sodium, magnesium, and hydride species at the NaH/MgO interface plays a pivotal role in the reduction of N2 to NHx species. These reactive NHx intermediates then deprotonate the aryl C-H bond, attack the alkali-interacted aryl ring, and drive the formation of sodium anilide on the surface. Subsequent protonation of sodium anilide yields aniline with high selectivity (>90%). This work demonstrates the feasibility of transforming N2 and simple arenes into key nitrogen-containing organic compounds via a solid surface-mediated process, thereby opening ample room for developing heterogeneous catalysts for the transformation of N2 and organic substrates.

Yongli Cai is an associate professor at the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences, where she studies the conversion of dinitrogen into nitrogen-containing compounds. Jianping Guo is a professor at the Dalian Institute of Chemical Physics, and his research aims to elucidate the distinctive properties of hydride, amide, and imide materials. Ping Chen is a professor at the Dalian Institute of Chemical Physics and director of the Hydride Energy Research Center. Her research encompasses hydrogen storage, hydride-mediated dinitrogen fixation, and hydride ion transport and focuses on developing hydride chemistry for sustainable energy conversion and utilization.

Organic-based luminescent materials have broad applications across illumination, display, and imaging. However, intramolecular vibrations and intermolecular interactions, such as π-π stacking, can induce non-radiative transition and lead to low efficiency and fluorescence quenching for solid-state materials, especially for small conjugated molecules. In the present study, a facile yet versatile conceptual approach to fabricate a new type of luminescent materials, i.e., alkali metal N-heteroarene salts, was developed via a metal substitution strategy. Over 30 solid-state ionic compounds have been designed and synthesized accordingly. These compounds possess rigid crystal structures through forming an ionic bonding network of metal‒N bonds and cation-π interactions, which can minimize the vibrations of individual molecules, thereby suppressing non-radiative transition. Consequently, some small conjugated molecules with negligible fluorescence, such as imidazole, indole, and azaindole, become strong emitters upon alkali metal substitution. The alkali metal substitution forms an N-heterocyclic anion owing to the Lewis acidity of the alkali metal cation, thus increasing the electron density on the conjugated system. Concurrently, the formation of N-heterocyclic anions tailors band gaps of these organic salts, enabling diverse fluorescent emissions across the visible spectrum. The applications of these organic salts in information anti-counterfeiting are also demonstrated successfully.

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.

Alkali metal pyridinolates have recently emerged as promising materials for reversible hydrogen storage owing to their high hydrogen capacities, simple synthesis, low cost, air stability, and favorable dehydrogenation thermodynamics. Given that these compounds originate from organic precursors that exhibit tautomerism, this study investigates the effect of tautomeric equilibria on their hydrogen storage performance. Using three positional isomers of lithium pyridinolate as representative model compounds, density functional theory calculations combined with experimental results reveal divergent reactivity patterns. In lithium 2-pyridinolate, the tautomeric equilibrium favors the lithium 2-pyridonate form; however, the intrinsic amide resonance stabilization in this tautomer hinders complete hydrogenation, leading to a stable intermediate that cannot be reversibly dehydrogenated under moderate conditions. Lithium 3-pyridinolate, which exists exclusively in this form, undergoes complete hydrogenation to form lithium 3-piperidinolate; yet this hydrogen-rich compound cannot be efficiently dehydrogenated under moderate conditions because of its high thermodynamic stability. In contrast, lithium 4-pyridinolate can tautomerize to its pyridonate form, but the para-arrangement of the C--O and N-Li groups in the latter reduces its stability. As a result, lithium 4-pyridinolate, being the most stable tautomer, undergoes complete hydrogenation to form lithium 4-piperidinolate, which can also be reversibly dehydrogenated with a conversion of 99.6 % at temperatures as low as 100 degrees C due to its favorable thermodynamics. Overall, this study demonstrates the significance of considering tautomerism in the design of organic-based hydrogen storage materials and presents the lithium 4-pyridinolate/4-piperidinolate pair as a promising new system for reversible hydrogen storage.

Significant progress has been made in materials development for hydride ion (H−) conduction and H−-mediated electrochemical devices. However, a gas-solid H− battery (g-HIB) that utilizes H2 and metals as the active materials of the electrodes and offers the potential for high capacity and energy density has yet to be developed. Here, a typical metal-hydrogen system, Mg-H2, is employed to build such a g-HIB. Experimental results validate that hydrogenation and dehydrogenation of the anode lead to electric energy output and input, respectively, in the Mg|3CeH3@BaH2|H2 developed. This g-HIB exhibits an initial capacity of 1,526 mAh/g and maintains a capacity retention of over 70% after 60 cycles. It operates effectively across a wide temperature range of −20°C to 90°C. The integration of this g-HIB with a secondary ion battery could create a novel hydrogen-electricity co-storage system that can be applied to hydrogen-electricity powertrains of fuel cell vehicles or drones to deliver a high hydrogen energy efficiency of 93.9%.

Lithium amide-lithium hydride composite (LiNH2-2LiH), a composite hydride with a high hydrogen capacity of 10.29 wt.%, has long been considered a promising candidate for hydrogen storage; however, its application is hindered by the thermodynamic stability and sluggish kinetics associated with N─H and Li─H bond cleavage and formation during thermally driven de/re-hydrogenation. Herein, we report that the photoexcitation of LiNH2 under UV illumination (0.8 W·cm-2) induces homolytic N─H bond cleavage and produces a distinctive photo-response with simultaneous evolution of H2, N2, and NH3. Coupling LiNH2 with LiH enables UV-driven hydrogen release with effective suppression of gaseous byproducts. Under high-intensity full-spectrum illumination (2.9  W·cm-2), the combined non-thermal and photothermal effects allow complete dehydrogenation of LiNH2-2LiH (>10.0 wt.%), and near-full reversibility over 6 cycles (capacity retention ca. 99%). We further realized direct hydrogen release from LiNH2-2LiH under natural sunlight. This photo-induced destabilization strategy provides a general route to activate strong bonds in amide-hydride composites and offers a promising approach toward solid-state hydrogen storage under mild conditions.

Plasma-catalytic ammonia synthesis is an emerging alternative approach for the sustainable conversion of dinitrogen (N2) to ammonia (NH3) using renewable electricity. However, the development of efficient catalysts for plasma-driven ammonia synthesis remains a formidable challenge. Herein, we report that calcium imide (CaNH) functions as an active, transition-metal-free catalyst for plasma-driven ammonia synthesis. Under 25 W and 20 kHz dielectric barrier discharge (DBD) conditions, the ammonia synthesis rate over CaNH is approximately three times that of the blank test, representing a performance enhancement comparable to the widely studied benchmark Ni/Al2O3 catalyst. Combined experimental and computational results reveal that the CaNH surface, with plasma-generated coordinatively unsaturated calcium sites, plays a critical role in promoting the hydrogenation of NxHy species to generate NH3 rather than in the activation of N2-thus redefining the rate-determining step. This study unveils a new functionality of alkaline earth metal imides in plasma-catalytic ammonia synthesis, thereby offering greater opportunities for the development of new materials and active catalysts. Furthermore, this work provides new insights into the catalytic mechanism of other catalysts for plasma-catalytic ammonia synthesis.

Using a CeH2|3CeH3@BaH2|NaAlH4 hydride-ion battery (HIB) model, we observed that capacity decay originates not only from the cathode material itself but also from anode potential drift caused by interfacial instability. We proposed stabilization strategies to mitigate these effects, highlighting that interfacial compatibility is crucial for the cycling stability of HIBs.

Hydride-ion (H-) electrochemistry offers a promising route for next-generation energy storage due to the low mass and high theoretical energy density of H-carriers. However, the development of rechargeable hydride-ion batteries has been impeded by the lack of suitable electrode materials capable of reversible H-insertion/extraction and by severe interfacial challenges in all-solid-state configurations. Rare-earth hydrides, particularly CeH3, exhibit remarkable dual hydride-ion and electron conductivity. The stable Fm 3 m crystal structure minimizes their volume variations during de/re-hydrogenation, e.g., the volume changes by about 1% from CeH3 to CeH2. These intrinsic properties enable CeH3 and CeH2 to be potential electrode materials for an all-solid-state hydride-ion battery. Using the recently developed hydride ion conductor CeH3@BaH2 as electrolyte, we built a CeH2|CeH3@BaH2|CeH3 battery which delivers an initial discharge capacity of 79.5 mA h g-1 and maintains 40 mA h g-1 after 175 cycles at room temperature. A tandem stack configuration achieving a voltage of similar to 0.7 V and a thick-electrode battery with an areal capacity exceeding 13 mA h cm-2 were also assembled, demonstrating superior structural stability and the potential for applications. This work highlights the great potential of rare-earth hydrides for advanced energy storage. (c) 2026 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Abstract Directly using abundant air as nitrogen and oxygen source for the co-construction of C–N and N–O bonds under mild conditions is highly significant for establishing a sustainable route of synthesizing high-value C–N–O chemicals. However, the efficient and controllable activation of N2, O2, and carbon source for the selective C–N and N–O coupling in a one-step process remains a formidable challenge. Herein, we report a plasma–ultrasound catalytic process that enables direct selective conversion of air and phenol to nitroaromatic chemicals (nitrosophenol and nitrophenol) under mild conditions, delivering an overall yield of 8.1% with a high selectivity of 92.5% using a CeO2 catalyst. Mechanistic investigations reveal a crucial effect of air plasma in generating reactive oxygen and NOx species and triggering the subsequent phenol oxidization and nitration reactions in the solution. Coupling ultrasound and CeO2 catalyst in the liquid phase further promotes the formation of reactive species and targeted nitroaromatic products combined with the enhancement of both mass transfer and reaction kinetics by the ultrasonic cavitation effect.

Tandem catalysis depends critically on communication between functionally distinct active sites to orchestrate multistep reactions. Atomic-scale integration of such complementary sites would facilitate seamless intersite communication and efficient mass/energy transfer, yet remains elusive in heterogeneous tandem catalysis owing to intrinsic challenges of catalyst architecture engineering. Herein, we report K3PdH5, a ternary palladium hydride, with two distinct [PdH4] and [KH] lattice sites, which catalyzes tandem semihydrogenation-isomerization of internal alkynes with exceptionally high activity and selectivity, achieving (E)-alkene formation rates up to 2 orders of magnitude higher than existing systems. Mechanistic studies disclose that the [PdH4] site exhibits moderate alkyne/alkene chemisorption while impedes H2 activation, allowing semihydrogenation to (Z)-alkene; the basic [KH] site, on the other hand, drives (Z) → (E) isomerization to proceed via a delocalized π-allyl species stabilized by K cation-π interactions. By atomic-level coupling of these two-type active sites within one single lattice, K3PdH5 demonstrates a unique function mechanism that is inaccessible to conventional heterogeneous tandem catalysts.

Abstract Hydrogen storage remains a key challenge for widescale adoption of hydrogen as an energy vector. Lightweight complex hydrides offer high storage densities but suffer from hydrogen release/cyclability above the temperatures required for practical use. Here, we report on discoveries in ternary Reactive Hydride Composites (RHCs). We systematically tuned the LiBH₄ content in the well-established Mg(NH₂)₂ - LiH framework, achieving reversible hydrogen release at temperatures starting below 393 K and a capacity of 3.1 wt%; a decrease of 100 K compared to the Mg(NH₂)₂ - LiH system.This is a crucial step towards the use of complex hydride-based hydrogen carriers for stationary and onboard hydrogen storage applications. We demonstrate a reversible RHC within the utilisation range of low-grade waste heat from a fuel cell, alongside offering insight into the reaction pathways in these RHCs to inform the design of future materials.

Alkali metal-modified catalysts significantly enhance the hydrogen storage performance of MgH2, yet the fundamental mechanisms of their promotional effects remain poorly understood. This study systematically investigates how Na and K promote the hydrogenation of commercial Mg powder over TiO2-based catalysts through combined experimental and theoretical approaches. Experimental results demonstrate that Na/K-modified TiO2 dramatically improves Mg hydrogen absorption: the addition of 5 wt% K-TiO2 reduces the hydrogen absorption peak temperature from ca. 300 °C (pure Mg) to 90 °C. Notably, Mg + 5 wt% K-TiO2 achieves 5.5 wt% H2 absorption capacity within 60 min at 100 °C, representing a 37% improvement over TiO2-only composites. Density functional theory calculations reveal that electron transfer from Na and K to TiO2 creates an electron-enriched interface, substantially reducing the energy barriers for hydrogen dissociation and diffusion. These findings elucidate how alkali metal promoters modulate electronic structure and reaction kinetics, providing a mechanistic foundation for rational design of advanced hydrogenation catalysts.

Complex formation in monometal organic compounds remains largely unexplored. Here, we report the first experimental investigation of complex formation in lithium phenoxide, Li(C6H5O). Varying the LiOH/phenol ratio yields lithium-rich and phenol-rich complexes; notably, the lithium-rich complex outperforms Li-phenoxide and phenol-rich complexes, achieving up to 48.1% conversion in solid-state dehydrogenation.

Directly converting dinitrogen (N 2 ) into valuable nitrogen-containing compounds remains an enduring challenge in chemical synthesis. Here, we report the direct cyanation of aromatic substrates using N 2 and methane (CH 4 ) at atmospheric pressure facilitated by a custom-built, air-free dielectric barrier discharge (DBD) plasma system. A broad range of aromatic compounds, including benzene, were successfully transformed into their corresponding aromatic nitriles. Both experimental and computational evidence suggested that the reaction proceeds primarily via the in situ generation of •CN radicals from N 2 and CH 4 within the plasma zone. Subsequent radical addition to aromatic rings allowed the one-pot formation of aryl nitriles. This approach represents a major advancement in dinitrogen-based organic methodologies, providing an efficient alternative to conventional cyanation methods that heavily rely on lengthy synthetic routes and hazardous cyanide reagents.