Vertically Staggered Porous Ni2P/Fe2P Nanosheets with Trace Ru Doping as Bifunctional Electrocatalyst for Alkaline Seawater Splitting

Abstract Designing a bifunctional electrocatalyst with high performance and low‐cost is of great significance to promote the large‐scale application of water splitting. Herein, porous Ru‐Ni2P/Fe2P heterojunction nanosheets with a vertically staggered structure are rationally fabricated to boost alkaline seawater splitting under large current densities. The Ru‐Ni2P/Fe2P catalyst exhibits remarkable activity in alkaline media, requiring only 274 and 331 mV at a large current density of 1000 mA cm −2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Additionally, the NiFeOOH layer formed on the surface of Ru‐Ni2P/Fe2P is proposed as the active phase to promote the OER performance. Furthermore, an anion exchange membrane (AEM) electrolyzer assembled by Ru‐Ni2P/Fe2P electrocatalyst exhibits excellent long‐term durability over 100 h, achieving a current density of 500 mA −2 at 2.0 V in alkaline seawater at 60 °C. Theoretical calculations reveal that the Ni2P/Fe2P heterojunction integration with trace Ru leads to balanced adsorption and desorption properties. Moreover, the active sites of Ru‐Ni2P/Fe2P are confirmed, in which Ni site is favorable for HER and Fe site is conducive to OER. This work provides an insight into designing a highly efficient and cost‐effective bifunctional electrocatalyst for overall seawater splitting.