Amorphous/Crystalline Nanostructured WP/CoP-FeP4/NF Heterojunctions for Efficient Electrocatalytic Overall Water Splitting

Transition-metal catalysts have significant potential for achieving commercial hydrogen production from electrolytic water due to their low cost and exceptional catalytic performance in overall water splitting. The electronic structure, active sites, and reaction kinetics of the catalyst can be optimized by compounding transition metals, thereby further enhancing its catalytic activity. Here, a nonprecious metal catalyst WP/CoP-FeP4/NF is designed. In WP/CoP-FeP4/NF, the nanosheets form a regular array structure, and the nanowires grow outward from the voids of the nanosheet arrays. Additionally, a large number of nanoparticles are attached to both the surfaces of the nanowires and those of the nanosheets. The nanostructures in WP/CoP-FeP4/NF are small, with both nanosheet nanowires and nanoparticles being less than 200 nm in size. The acceleration of optimized electronic structure, oxygen vacancies, and interfacial engineering between the catalytic performance in overall water splitting are investigated. WP/CoP-FeP4/NF is evaluated for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at current densities of 100 mA cm–2 in alkaline solutions with overpotentials as low as 128 and 244 mV. The catalytic performances of both HER and OER remained at a high level (98% for the HER and 99.83% for the OER) even after continuous operation under 100 mA cm–2 current density for up to 80 h (HER) or 46 h (OER). This work provides an idea for the design of catalysts with crystalline and amorphous heterostructures for overall water splitting at high currents.