Self-supporting Ru3+ doped copper phosphate with Pt/C-like hydrogen evolution reaction activity

Abstract

Designing a bifunctional catalyst with excellent water splitting properties in both alkaline electrolyte and seawater remains a challenge. Metal phosphates are widely reported oxygen evolution reaction (OER) materials. However, their poor conductivity and low electrochemical properties still need to be improved. Since there are almost no corresponding hydrogen evolution reaction (HER) or OER applications of copper phosphate, here we have applied copper foam (CF) as a conductive substrate, as well as a copper source to synthesize self-supporting Cu₃(PO₄)₂/CF. Meanwhile, we introduced Ru³⁺ into the synthetic environment of Cu₃(PO₄)₂ to optimize its electrochemical performance. Luckily, Ru³⁺ was evenly doped into Cu₃(PO₄)₂ and the obtained Ru–Cu₃(PO₄)₂/CF showed excellent electrochemical performance in both alkaline electrolyte and seawater. Specifically, it displayed enhanced OER properties over pure Cu₃(PO₄)₂/CF and showed Pt/C-like HER activity during electrocatalytic testing. Corresponding computational theory data confirmed that the introduced Ru improved the inherent electrochemical activity of Ru–Cu₃(PO₄)₂/CF and thereby accelerated its electrocatalytic water splitting properties. Thus, this work not only provides an efficient bifunctional catalyst in both alkaline electrolyte and seawater, but will also lay experimental/theoretical foundations for other metal phosphates.