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Transition metal dichalcogenide materials have been explored extensively as catalysts to negotiate the hydrogen evolution reaction, but they often run at a large excess thermodynamic cost. Although activating strategies, such as defects and composition engineering, have led to remarkable activity gains, there remains the requirement for better performance that aims for real device applications. We report here a phosphorus-doping-induced phase transition from cubic to orthorhombic phases in CoSe 2 . It has been found that the achieved orthorhombic CoSe 2 with appropriate phosphorus dopant (8 wt%) needs the lowest overpotential of 104 mV at 10 mA cm −2 in 1 M KOH, with onset potential as small as −31 mV. This catalyst demonstrates negligible activity decay after 20 h of operation. The striking catalysis performance can be attributed to the favorable electronic structure and local coordination environment created by this doping-induced structural phase transition strategy. Transition metal dichalcogenides represent an exciting class of earth-abundant hydrogen-from-water electrocatalysts, although low efficiencies limit commercialization. Here, authors present a doping strategy to induce a phase transition in cobalt selenide and boost H 2 -evolution performance.

Seawater electrolysis using renewable electricity offers an attractive route to sustainable hydrogen production, but the sluggish electrode kinetics and poor durability are two major challenges. We report a molybdenum nitride (Mo 2 N) catalyst for the hydrogen evolution reaction with activity comparable to commercial platinum on carbon (Pt/C) catalyst in natural seawater. The catalyst operates more than 1000 hours of continuous testing at 100 mA cm −2 without degradation, whereas massive precipitate (mainly magnesium hydroxide) forms on the Pt/C counterpart after 36 hours of operation at 10 mA cm −2 . Our investigation reveals that ammonium groups generate in situ at the catalyst surface, which not only improve the connectivity of hydrogen-bond networks but also suppress the local pH increase, enabling the enhanced performances. Moreover, a zero-gap membrane flow electrolyser assembled by this catalyst exhibits a current density of 1 A cm −2 at 1.87 V and 60 o C in simulated seawater and runs steadily over 900 hours. Efficient catalysts for seawater electrolysis are crucial for sustainable hydrogen production but struggle with slow kinetics and low durability. Here, the authors report a molybdenum nitride catalyst that in situ generates ammonium groups, enhancing both performance and stability in natural seawater.

Many platinum group metal-free inorganic catalysts have demonstrated high intrinsic activity for diverse important electrode reactions, but their practical use often suffers from undesirable structural degradation and hence poor stability, especially in acidic media. We report here an alkali-heating synthesis to achieve phase-mixed cobalt diselenide material with nearly homogeneous distribution of cubic and orthorhombic phases. Using water electroreduction as a model reaction, we observe that the phase-mixed cobalt diselenide reaches the current density of 10 milliamperes per square centimeter at overpotential of mere 124 millivolts in acidic electrolyte. The catalyst shows no sign of deactivation after more than 400 h of continuous operation and the polarization curve is well retained after 50,000 potential cycles. Experimental and computational investigations uncover a boosted covalency between Co and Se atoms resulting from the phase mixture, which substantially enhances the lattice robustness and thereby the material stability. The findings provide promising design strategy for long-lived catalysts in acid through crystal phase engineering. Noble-metal-free catalysts often show stability issues in acidic media due to structural degradation. Here authors show that phase-mixed engineering of cobalt diselenide electrocatalysts can enable greater covalency of Co-Se bonds and improve robustness for catalyzing hydrogen evolution in acid.

The electroreduction of water for sustainable hydrogen production is a critical component of several developing clean-energy technologies, such as water splitting and fuel cells. However, finding a cheap and efficient alternative catalyst to replace currently used platinum-based catalysts is still a prerequisite for the commercialization of these technologies. Here we report a robust and highly active catalyst for hydrogen evolution reaction that is constructed by in situ growth of molybdenum disulfide on the surface of cobalt diselenide. In acidic media, the molybdenum disulfide/cobalt diselenide catalyst exhibits fast hydrogen evolution kinetics with onset potential of −11 mV and Tafel slope of 36 mV per decade, which is the best among the non-noble metal hydrogen evolution catalysts and even approaches to the commercial platinum/carbon catalyst. The high hydrogen evolution activity of molybdenum disulfide/cobalt diselenide hybrid is likely due to the electrocatalytic synergistic effects between hydrogen evolution-active molybdenum disulfide and cobalt diselenide materials and the much increased catalytic sites. There is substantial research into new catalysts for electroreduction of water. Here, the authors report a robust and active molybdenum disulfide/cobalt diselenide hydrogen evolution catalyst with onset potential of 11 mV and Tafel slope of 36 mV per decade, approaching the activity of platinum.

Development of low-cost and high-performance oxygen evolution reaction catalysts is key to implementing polymer electrolyte membrane water electrolysers for hydrogen production. Iridium-based oxides are the state-of-the-art acidic oxygen evolution reaction catalysts but still suffer from inadequate activity and stability, and iridium’s scarcity motivates the discovery of catalysts with lower iridium loadings. Here we report a mass-selected iridium–tantalum oxide catalyst prepared by a magnetron-based cluster source with considerably reduced noble-metal loadings beyond a commercial IrO 2 catalyst. A sensitive electrochemistry/mass-spectrometry instrument coupled with isotope labelling was employed to investigate the oxygen production rate under dynamic operating conditions to account for the occurrence of side reactions and quantify the number of surface active sites. Iridium–tantalum oxide nanoparticles smaller than 2 nm exhibit a mass activity of 1.2 ± 0.5 kA g Ir –1 and a turnover frequency of 2.3 ± 0.9 s −1 at 320 mV overpotential, which are two and four times higher than those of mass-selected IrO 2 , respectively. Density functional theory calculations reveal that special iridium coordinations and the lowered aqueous decomposition free energy might be responsible for the enhanced performance. Low-cost, high-performance oxygen evolution catalysts would facilitate implementation of water electrolysers for hydrogen production. Here the authors report a low-iridium mass-selected iridium–tantalum oxide catalyst with high intrinsic activity in acid and carefully evaluate oxygen production to account for parasitic reactions.

Finding highly efficient hydrogen evolution reaction (HER) catalysts is pertinent to the ultimate goal of transformation into a net-zero carbon emission society. The design principles for such HER catalysts lie in the well-known structure-property relationship, which guides the synthesis procedure that creates catalyst with target properties such as catalytic activity. Here we report a general strategy to synthesize 10 kinds of single-atom-doped CoSe 2 -DETA (DETA = diethylenetriamine) nanobelts. By systematically analyzing these products, we demonstrate a volcano-shape correlation between HER activity and Co atomic configuration (ratio of Co-N bonds to Co-Se bonds). Specifically, Pb-CoSe 2 -DETA catalyst reaches current density of 10 mA cm −2 at 74 mV in acidic electrolyte (0.5 M H 2 SO 4 , pH ~0.35). This striking catalytic performance can be attributed to its optimized Co atomic configuration induced by single-atom doping. Designing high performing low-cost nanomaterials for catalyzing hydrogen evolution reaction (HER) remains challenging. Here, the authors report a volcano-shape correlation between HER activity and cobalt atomic configuration in single-atom doped CoSe2-DETA (DETA = diethylenetriamine) nanobelts toward achieving high performance.

Low-density compressible materials enable various applications but are often hindered by structure-derived fatigue failure, weak elasticity with slow recovery speed and large energy dissipation. Here we demonstrate a carbon material with microstructure-derived super-elasticity and high fatigue resistance achieved by designing a hierarchical lamellar architecture composed of thousands of microscale arches that serve as elastic units. The obtained monolithic carbon material can rebound a steel ball in spring-like fashion with fast recovery speed (∼580 mm s −1 ), and demonstrates complete recovery and small energy dissipation (∼0.2) in each compress-release cycle, even under 90% strain. Particularly, the material can maintain structural integrity after more than 10 6 cycles at 20% strain and 2.5 × 10 5 cycles at 50% strain. This structural material, although constructed using an intrinsically brittle carbon constituent, is simultaneously super-elastic, highly compressible and fatigue resistant to a degree even greater than that of previously reported compressible foams mainly made from more robust constituents. Low-density compressible materials often suffer from fatigue-induced failure or limited elasticity. Here, the authors create a hierarchical multi-arch carbon material that achieves high compressibility, superior elasticity and fatigue resistance simultaneously, inspired by properties of arches in daily life.

The cost of fuel cell systems can be largely reduced by developing hydroxide exchange membrane fuel cells (HEMFCs) based on platinum group metal-free (PGM-free) catalysts. However, the sluggish hydrogen oxidation reaction (HOR) in alkaline electrolytes forces HEMFCs to use higher PGM loadings at the anode than proton exchange membrane fuel cells to sustain the desired power densities. Here we report nickel–molybdenum–niobium metallic glasses as PGM-free HOR catalysts. The optimal Ni 52 Mo 13 Nb 35 metallic glass exhibits an intrinsic exchange current density of 0.35 mA cm −2 , outperforming that of a Pt disk catalyst (0.30 mA cm −2 ). This catalyst also shows remarkable robustness in alkaline electrolyte with a wide stability window up to 0.8 V versus the reversible hydrogen electrode. When used as the anode, this catalyst enables power densities of 390 mW cm −2 in H 2 /O 2 fuel cells and 253 mW cm −2 in H 2 /air fuel cells, and shows negligible performance degradation over 50 h and 30 h, respectively. Hydroxide exchange membrane fuel cells operating in alkaline electrolyte are more cost-effective than their proton exchange membrane counterparts, but their performance is still considerably lower. Now, a Ni–Mo–Nb metallic glass is put forward as a hydrogen oxidation reaction catalyst with high activity and stability in alkaline electrolyte.

With the rapid development of anion exchange membrane technology and the availability of high-performance non-noble metal cathode catalysts in alkaline media, the commercialization of anion exchange membrane fuel cells has become feasible. Currently, anode materials for alkaline anion-exchange membrane fuel cells still rely on platinum-based catalysts, posing a challenge to the development of efficient low-Pt or Pt-free catalysts. Low-cost ruthenium-based anodes are being considered as alternatives to platinum. However, they still suffer from stability issues and strong oxophilicity. Here, we employ a metal–organic framework compound as a template to construct three-dimensional porous ruthenium–tungsten–zinc nanocages via solvothermal and high-temperature pyrolysis methods. The experimental results demonstrate that this porous ruthenium–tungsten–zinc nanocage with an electrochemical surface area of 116 m2 g−1 exhibits excellent catalytic activity for hydrogen oxidation reaction in alkali, with a kinetic density 1.82 times and a mass activity 8.18 times higher than that of commercial Pt/C, and a good catalytic stability, showing no obvious degradation of the current density after continuous operation for 10,000 s. These findings suggest that the developed catalyst holds promise for use in alkaline anion-exchange membrane fuel cells.

Our study examines the morphological and statistical differentiation within the Rhododendron pseudochrysanthum species complex through comparative analyses of macro- and micro-morphological characters. Using significance testing and cluster analysis, our results demonstrate that R. pseudochrysanthum Hayata ssp. morii (Hayata) Yamazaki var. taitunense Yamazaki is distinct from other members of the complex, namely R. morii Hayata, R. pseudochrysanthum Hayata, and R. hyperythrum Hayata. This taxon is characterized by glabrous mature leaves with revolute margins, larger flower buds with an elongated conical shape, larger pollen and seed sizes, and distinct pollen and seed morphology. Furthermore, R. pseudochrysanthum ssp. morii var. taitunense exhibits a restricted and localized distribution, occurring exclusively in low-elevation mountainous areas of Northern Taiwan. Overall, our results indicate that this taxon has undergone clear morphological differentiation from other taxa within the R. pseudochrysanthum species complex.