【Frontiers in HaiChuan Chemical Technology】Dalian Institute of Chemical Physics develops new electrodes for direct hydrogen production from seawater electrolysis

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Recently, the team led by Researcher Shao Zhigang from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, in collaboration with the team led by Professor Lin Wenfeng from Loughborough University, made an important breakthrough in the field of cathode materials for direct seawater electrolysis to produce hydrogen. The research team innovatively developed a platinum/cobalt hydroxide (Pt@Co(OH)₂) nanoarray electrode with a positively charged surface, which not only effectively prevents the deposition of calcium and magnesium hydroxides from seawater on the cathode surface, thereby avoiding scaling, but also accelerates the kinetics of the hydrogen evolution reaction. The findings related to this work have been published in the journal Applied Catalysis B: Environment and Energy. Hydrogen energy is one of the key clean energies that support the achievement of the \"dual carbon\" goals. By producing hydrogen through the electrolysis of seawater, it is possible to avoid conflicts over freshwater resources with industry and agriculture, offering broad prospects for industrial application. However, natural seawater has a near-neutral pH value, which not only slows down the kinetics of the hydrogen evolution reaction on its own ； During the electrolysis process, the local pH at the cathode increases, which also facilitates the formation of hydroxide precipitates from calcium and magnesium ions in seawater; these precipitates cover and block the active sites on the electrodes ； At the same time, high concentrations of chloride ions can also cause corrosion and wear on the electrodes. How to precisely regulate the microenvironment at the electrode-electrolyte interface, and simultaneously overcome the three major challenges of slow reaction kinetics, calcium and magnesium deposition and scaling, as well as chloride ion corrosion, has always been a key bottleneck that needs to be addressed in the field of seawater electrolysis for hydrogen production. In this study, the team successfully prepared Pt@Co (OH)₂ nanorarray electrodes on a nickel foam substrate through a two-step electrodeposition process. Thanks to the fact that the isoelectric point of cobalt hydroxide is higher than the pH value of seawater, the electrode surface carries a positive charge; this electrostatic repulsion prevents calcium and magnesium ions from migrating toward the cathode, thereby suppressing the deposition of hydroxides at the source ； The well-ordered nanarray structure can also provide a fast escape pathway for hydrogen bubbles, thereby further removing trace deposits from the electrode surface. Mechanistic studies show that the Pt sites in the material have a strong adsorption effect on active hydrogen (*H), while the Co sites have a strong adsorption effect on hydroxyl groups (*OH), thereby establishing an efficient mechanism for co-catalytic hydrolysis driven by these dual active sites ； At the same time, the electronic interaction between Pt and Co not only optimizes the desorption process of active hydrogen but also reduces the adsorption of chloride ions on the electrode surface, thereby significantly enhancing the corrosion resistance of the electrode. The pH asymmetric electrolyzer built using this electrode was able to operate stably for over 1,000 hours within a current density range of 100–1,000 mA cm⁻², thereby fully demonstrating the material’s excellent stability and potential for large-scale industrial application.