【Frontiers in HaiChuan Chemical Technology】Dalian Institute of Chemical Physics has developed an industrial-grade cobalt phosphide-based anode catalyst with stable current density and non-precious metal composition

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Recently, the research team led by Researcher Zhang Fuxiang from the Group on Solar Hydrogen Production and Storage Materials and Catalysis (Group DNL1621) in the Solar Energy Research Department of our institute has made new progress in the research on the efficient and stable decomposition of water to produce hydrogen using non-precious metal-based materials. Taking into account various factors such as the mechanical stability of electrocatalysis, the structural stability of materials, and the electrocatalytic stability, the team proposed a new electrode design concept based on the \"All-for-one Design\" approach. They developed a cobalt phosphide-based anode catalyst that is not made of precious metals and can operate stably at industrial-level high current densities (500 mA cm⁻²) for over 1000 hours, offering a new solution for the low-cost, large-scale production of green hydrogen through water electrolysis. Electrolytic water splitting for hydrogen production is the core technology for generating green hydrogen using renewable energy sources such as solar and wind energy, and it holds great significance for establishing a future clean energy system and achieving the \"dual carbon\" goals. However, the slow kinetics of the anodic oxygen evolution reaction (OER) during water electrolysis is a bottleneck in the entire process, often requiring expensive and rare precious metal catalysts such as iridium and ruthenium. Developing inexpensive, efficient, and stable non-precious metal catalysts is a key challenge that needs to be addressed urgently in this field. Although non-precious metal catalysts such as transition metal phosphides (TMPs) show potential as alternatives, they suffer from stability issues such as rapid loss of activity and easy detachment from the electrodes under the high current densities required in industrial production, making it difficult for them to meet the requirements for commercial use. In this work, starting from the physical and chemical stability of catalysts, the team systematically proposed an integrated design strategy to jointly optimize various key parameters that affect catalyst performance – ranging from the macroscopic electrode structure to the microscopic atomic arrangement. By adopting multiple approaches, they overcame the issues of high overpotential in water electrolysis catalysts, as well as their low stability, such as easy detachment and deactivation under high-current operation conditions. To fundamentally address the issue of physical delamination of the catalyst during intense oxygen evolution, the research team employed a quasi-in-situ growth method. The catalyst powder was placed together with a conductive substrate (nickel foam) in a reaction vessel, and through solvothermal treatment, the catalyst \"took root\" on the surface of the substrate, forming a strong bond that enhanced the mechanical stability of the electrode. In terms of the microstructural design of the catalyst, the team created cobalt phosphide (CoP) in the form of two-dimensional nanosheets, which provided numerous active sites for the reaction. At the same time, efficient electron transport pathways were established, ensuring smooth flow of current within and outside the catalyst and preventing local overheating and structural damage caused by charge buildup. Furthermore, the team precisely controlled the phosphidation process at the atomic scale to create a polycrystalline heterostructure in which two crystal phases, CoP and Co₂P, coexist, and trace amounts of sulfur atoms were introduced for doping modification. The formation of heterogeneous interfaces and the introduction of sulfur atoms effectively regulated the electron cloud distribution at the cobalt active centers, optimizing their binding energy with reaction intermediates, thereby enhancing the intrinsic activity of the catalyst. Thanks to the aforementioned integrated collaborative design, the CoₓP-HS anode catalyst prepared by the team exhibited high stability, maintaining continuous and stable operation for over 1000 hours at an industrial current density of 500 mA cm⁻² without any significant decline in performance. The team assembled this anode with a self-made nickel-molybdenum oxide cathode to form a full electrolytic cell, and integrated it with commercial solar cells to create a photovoltaic-electrolysis of water (PV-EC) integrated device. This device achieved a solar-to-hydrogen conversion efficiency of 27.10% and operated stably for over 500 hours, demonstrating its potential for use in the future production of hydrogen from renewable energy sources. The integrated design concept proposed in this study systematically combines multi-scale optimization strategies from the macroscopic to the microscopic level, offering new approaches for developing efficient and stable electrocatalysts for industrial applications. The relevant research findings were published recently in the Journal of Energy Chemistry under the title “All-for-one design of cobalt phosphide anode for robust water oxidation and solar-to-chemical conversion”. The co-first authors of this work are Dr. Rashid Mehmood from our institute, Associate Researcher Fan Wenjun, and Dr. Du Shiwen. The above work was supported by projects such as the **Key Research and Development Program** and the National Natural Science Foundation.