Interfacial electronic modification of bimetallic oxyphosphides as Multi-functional electrocatalyst for water splitting and urea electrolysis

Electrochemical water or wastewater splitting is a sustainable development approach for both hydrogen generation and pollutant elimination. Herein, an N-engineering ultrathin bimetallic oxyphosphides nanosheets on Ni foam (CoNiOP/NF) as a multi-functional binder-free electrode was synthesized for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and urea oxidation reaction (UOR). The catalytic activity of the composites could be improved through introducing N-doping via an in-situ transformation and heterogeneous metals by ion exchange. Both theoretical calculation and experimental investigations confirmed that electrons transferred from metal centers to anion at the interface, which was favor to accelerate the phase transformation to electrochemically active species and optimize the intermediates adsorption dynamics, thus providing greatly enhanced electrocatalytic activities. Assembled an electrolyzer using UOR replaced OER, it required only 1.42 V to achieve 50 mA cm-2 with long-term stability, 214 mV less than that required for HER‖OER. This work would be beneficial for the exploitation of non-noble metal-based electrocatalysts for simultaneous realization of energy-saving urea-assisted electrolytic hydrogen production and urea-containing wastewater purifying.