Dual-function CoP on nitrogen doped carbon framework with induced interfacial coupling for overall water splitting

Abstract

Strong interfacial coupling in the hybrid catalysts could enhance catalytic performances. In this work, N, P were co-doped in zeolitic imidazolate framework-67 (ZIF-67) derived Co-based materials (denoted as CoP/NC) via in-situ carbonization and phosphating strategy, which accordingly induced strong interfacial coupling, leading to promote the catalytic activity in overall water splitting. In detail, the CoP/NC-2 presents the overpotential of 98 and 139 mV for hydrogen evolution reaction (HER) in 0.5 M H2SO4 and 1.0 M KOH at 10 mA cm−2, respectively, and 295 mV for oxygen evolution reaction (OER) in 1.0 M KOH at 20 mA cm−2, which is excellent during the non-noble metal-based catalysts. It also achieved a potential of 1.69 V (η20) in the overall water splitting. Density functional theory (DFT) based calculation reveals that the in-situ N, P co-doping induced strong interface coupling, which enhances the interaction in the interface of catalysts and improves electron conduction. More importantly, it contributes to adjusting electronic structure and d-band center, optimizing the adsorption energy for HER and/or OER and improving the kinetics of water splitting reaction. This work sheds new light on the heteroatom doping strategy to construct bifunctional transition metal-based electrocatalyst with boosting electrocatalytic performance in energy conversion application.