Amorphous High-Entropy FeCoNiMo Phosphides as Efficient Bifunctional Electrocatalysts for Seawater Splitting

Abstract

Developing high-efficiency, stable bifunctional electrocatalysts for seawater splitting is vitally essential. In this work, we fabricated an amorphous high-entropy FeCoNiMo (FCNM) phosphide bifunctional catalyst on nickel foam (NF) via facile, one-step electrodeposition at room temperature. The obtained FCNMP possessed a three-dimensional porous structure composed of ultrathin nanosheets, which is conducive to providing a large active specific surface area and promoting ion/mass transport during the reaction. The FCNMP/NF electrocatalyst exhibited outstanding electrocatalytic performance in simulated alkaline seawater, requiring the low overpotentials of 287.5 and 201.3 mV for the oxygen evolution reaction and hydrogen evolution reaction, to reach a current density of 50 mA/cm², respectively. The enhanced catalytic performance was attributed to the synergistic effects of the optimized electronic structure of high-entropy materials, the abundant accessible active sites from the ultrathin nanosheet morphology, and the amorphous structure. Furthermore, when FCNMP/NF was used as the cathode and anode catalysts for seawater splitting, it required only 1.75 V to reach 50 mA/cm² for overall simulated alkaline seawater splitting. The system operated stably for over 50 h, demonstrating great potential for practical applications. Moreover, the catalyst maintained a favorable electrochemical performance in real alkaline seawater. This study provides a novel strategy for the design of high-performance bifunctional electrocatalysts for alkaline seawater splitting.

Keywords

Seawater splitting / High-entropy / Electrocatalysts / Phosphides

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