CoP particles embedded in N-doped two-dimensional carbon sheets as efficient electrocatalyst for water splitting

Abstract

We reported the synthesis of CoP particles embedded in N-doped carbon sheets (CoP/NCS) as an efficient electrocatalyst for water splitting. In the synthesis, Co2+ ions were firstly coordinated with 8-hydroxy quinoline (8-HQ) to form a sheet-like precursor (Co-HQ). Then, the CoP/NCS was obtained by controllable phosphorization of Co-HQ precursor. The electrochemical test indicated that CoP/NCS can be used as a bifunctional catalyst to catalyze hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 M KOH. For HER, the CoP/NCS can drive a current density of 10 mA cm−2 (η10) at a low overpotential of 71 mV. The catalyst also shown the good activity for OER with the onset overpotential of 254 mV, and η10 of 313 mV. The cell assembled by using CoP/NCS as both cathode and anode needed a cell voltage of 1.63 V to achieve current density of 10 mA cm−2. The results also indicated that the catalytic activity of CoP/NCS is related to the suitable conductivity and surface areas. The interaction between carbon sheets and CoP particles is also favorable for improving the performance.