Trace N introduction accelerates desorption of intermediates for the HER and formation of MOOH species for the OER on NiCoP to boost overall water splitting

Abstract

Electrochemical overall water splitting (OWS) with high-efficiency electrocatalysts can directly convert water into hydrogen. This paper demonstrates a commercially applicable way to effectively trigger OWS on a low-cost NiCoP material by trace N doping. Density functional theory (DFT) helps to understand the effect of trace N introduction on the lattice parameters of NiCoP and the Gibbs free energy of H adsorption (ΔG_H*). N-NiCoP/NF requires only 119 and 250 mV overpotentials to reach 50 mA cm⁻² for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). For OWS, the catalyst exhibits satisfactory activity (52 mA cm⁻² with a low voltage of 1.626 V) and long term durability (100 h). In situ UV-vis clarifies that N cooperation accelerates the formation of MOOH species in the OER and the priority of CoOOH formation over NiOOH has been observed in situ for the first time. This study may provide a promising strategy for consideration in designing and optimizing novel electrocatalysts.