The use of highly-active and robust catalysts is crucial for producing green hydrogen by water electrolysis as we strive to achieve global carbon neutrality. Noble metals like platinum are currently used catalysts in industry for the hydrogen evolution, but suffer from scarcity, high price and unsatisfied performance and stability at large current density, restrict their large-scale implementations. Here we report the synthesis of a type of monolith catalyst consisting of a metal disulfide (e.g., tantalum sulfides) vertically bonded to a conductive substrate of the same metal tantalum by strong covalent bonds. These features give the monolith catalyst a mechanically-robust and electrically near-zero-resistance interface, leading to an excellent hydrogen evolution performance including rapid charge transfer and excellent durability, together with a low overpotential of 398 mV to achieve a current density of 2,000 mA cm−2 as required by industry. The monolith catalyst has a negligible performance decay after 200 h operation at large current densities. In light of its robust and metallic interface and the various choices of metals giving the same structure, such monolith materials would have broad uses besides catalysis.
Constructing stable electrodes which function over long timescales at large current density is essential for the industrial realization and implementation of water electrolysis. However, rapid gas bubble detachment at large current density usually results in peeling-off of electrocatalysts and performance degradation, especially for long term operations. Here we construct a mechanically-stable, all-metal, and highly active CuMo6S8/Cu electrode by in-situ reaction between MoS2 and Cu. The Chevrel phase electrode exhibits strong binding at the electrocatalyst-support interface with weak adhesion at electrocatalyst-bubble interface, in addition to fast hydrogen evolution and charge transfer kinetics. These features facilitate the achievement of large current density of 2500 mA cm−2 at a small overpotential of 334 mV which operate stably at 2500 mA cm−2 for over 100 h. In-situ total internal reflection imaging at micrometer level and mechanical tests disclose the relationships of two interfacial forces and performance of electrocatalysts. This dual interfacial engineering strategy can be extended to construct stable and high-performance electrodes for other gas-involving reactions.
Water electrolysis can occur in alkaline, neutral, and acidic media. Neutral water electrolysis is environmentally friendly and suitable for microbial electrolysis, but is faced with problems of sluggish kinetics induced by the low concentration of adsorbed reactants on the catalyst surface and a large energy loss during the reaction. [4] In comparison, alkaline water electrolysis has a wider application due to the low cost and good stability of the catalysts but currently suffers from problems of a high ohmic resistance, sluggish kinetics, and a low current density. [5] Compared with neutral and alkaline water electrolysis, acidic water electrolysis such as a proton exchange membrane water electrolyzer (PEMWE) can reach a higher current density (>2 A cm -2 ) due to higher proton conductivity and lower ohmic resistance. In addition, PEMWE has the advantages of high purity H 2 production, a fast response speed and few side reactions. [6] In recent years, much effort has been devoted to acidic water electrolysis, but there are still several challenges for its large-scale applications. A major challenge is the poor performance at the anode, which requires high-performance catalysts to reduce the overpotential and improve the overall efficiency. [7] First, the intrinsic activity of acidic OER catalysts needs to be improved due to the sluggish four-electron-transfer kinetics of the OER compared with the two-electron-transfer hydrogen evolution reaction (HER), which needs to be improved. Second, most reported catalysts cannot reach high current density (>200 mA cm -2 ) and meet the requirements of industrial use. Third, the dissolution and peeling of the catalyst from the electrode in oxidative and corrosive OER conditions worsen their activity and stability, and thus limits the long-term use of these catalysts.OER occurs at the interface between a catalyst and an acidic electrolyte, where the absorption and desorption of the intermediates is crucial for the whole catalytic reaction. Therefore, it is important to control the absorption and desorption energy of intermediates to improve the overall reaction efficiency. [8] Low-dimensional materials including 0D (nanoparticles/ nanodots), 1D (nanorods/nanowires), and 2D (nanosheets/ nanoplates) have received much attention in the energy conversion field because of their high specific surface area, abundant active sites, tunable electronic structure, and possible different
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