An Intriguing Pea-Like Nanostructure of Cobalt Phosphide on Molybdenum Carbide Incorporated Nitrogen-Doped Carbon Nanosheets for Efficient Electrochemical Water Splitting

Abstract

The development of noble-metal-free, efficient, electrochemical, water-splitting catalyst systems has attracted considerable attention in recent times. In this study, a metal–organic framework based synthetic route to couple two non-noble-metal-based catalysts, CoP and Mo2C, supported on nitrogen-doped carbon has been developed. The strategy enables the formation of a nanohybrid with an attractive pea-like morphology, in which spherical CoP particles (≈10 nm) are embedded on two-dimensional nitrogen-doped carbon enriched with ultrafine Mo2C nanoparticles. This composition boosts the electrochemical alkaline water-splitting reaction by showing overpotentials (η10) of only 94 and 265 mV for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, at a current density of 10 mA cm−2. Additionally, in an acidic medium, the η10 values are 107 and 330 mV for HER and OER, respectively; this suggests good bifunctionality at both lower and higher pH levels. Overall water splitting has been demonstrated by the developed catalyst at a cell voltage of 1.64 V for a current density of 10 mA cm−2 in alkaline medium, and a constant current is produced for more than 40 h under chronoamperometric conditions. This study describes the combination of two nanocomponents, with interconnected surface structures, which result in highly active and stable electrocatalytic performance.