One-pot synthesis of N and P Co-doped carbon layer stabilized cobalt-doped MoP 3D porous structure for enhanced overall water splitting

Abstract

Transition metal phosphides are novel electrocatalysts that can be used to replace noble metals for the electrochemical production of hydrogen. In this work, N and P co-doped carbon-coated cobalt-doped molybdenum phosphide (CoMoP@N,P-C) nanoparticles are explored as electrocatalyst for overall water splitting. The presence of a unique three-dimensional (3D) porous structure in CoMoP@N,P-C offers abundant catalytic active sites for the penetration of the electrolyte solution, thereby facilitating the transfer of ions. In addition, cobalt doped into MoP increases the catalytic activity, and N and P co-doped carbon improves the electrical conductivity of the carbon matrix. Subsequently, the synergy between CoMoP cores and N, P-C shells enhances the total hydrolysis performance of the electrocatalyst in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) processes. At a current density of 10 mA/cm2 in 1 M KOH, HER and OER overpotential of the CoMoP@N, P-C are 152 mV and 296 mV, respectively. Moreover, the cell voltage of CoMoP@N, P-C as a bifunctional electrode for overall water splitting is 1.62 V (at 10 mA/cm2), which is close to that of the full noble-metal electrode (RuO2 || Pt/C, 1.58 V). Overall, the CoMoP@N, P-C bifunctional catalyst shows great potential for replacing noble-metal electrodes in water splitting applications.