Construction of a CoP/MnP/Cu3P heterojunction for efficient methanol oxidation-assisted seawater splitting†

Abstract

Methanol oxidation-assisted direct seawater electrolysis has emerged as a potent technology for efficient hydrogen (H₂) production alongside high-value chemicals such as formic acid and formaldehyde. However, the large-scale application of this technology heavily relies on developing highly active and robust bifunctional electrocatalysts for methanol oxidation and hydrogen evolution reactions (MOR/HER). Herein, we report a simple hydrothermal-phosphorylation method to synthesize a heterostructured catalyst on copper foam, comprising CoP, MnP, and Cu₃P (CoP/MnP/Cu₃P@CF). The synergistic interaction among the heterogeneous components endowed CoP/MnP/Cu₃P@CF with excellent MOR, oxygen evolution reaction (OER), and HER performance in alkaline seawater electrolytes. Notably, the MOR-assisted CoP/MnP/Cu₃P@CF-based seawater electrolyzer catalyst required only 1.410 V to achieve a current density of 10 mA cm⁻², significantly lower than the 1.681 V required for an OER–HER seawater electrolyzer. Additionally, the MOR-assisted electrolyzer exhibits high faradaic efficiency and cycling stability, offering the potential for sustainable energy-efficient H₂ production.