Amorphous NiCo2O4 modified NiCoP heterojunction enhanced electrochemical oxygen evolution reaction performance

Abstract

The development of efficient non-precious metal electrocatalysts for the oxygen evolution reaction (OER) is crucial for addressing the pressing challenges of energy and environmental sustainability. In this study, we employed a continuous hydrothermal-oxidation-phosphating method to incorporate phosphorus (P) into the spinel phase, transforming the NiCo2O4 structure into NiCoP. Notably, this phosphating phase transition retains some amorphous NiCo2O4, which promotes the formation of amorphous/crystalline heterostructures (a-NiCo2O4/NiCoP-300, denoted as NCP-300). The phase transition engineering creates the amorphous/crystalline heterogeneous interface that enhances OER electrocatalytic performance by generating more active sites and defects. The overpotentials required for NCP-300 to achieve current densities of 10 mA cm-2 and 50 mA cm-2 in alkaline media are 332 mV and 400 mV, respectively, with a Tafel slopeof 87 mV dec-1. These values are lower than those of its precursor, NiCo2O4-300 (η10 = 355 mV, η50 = 434 mV, Tafel slope = 92 mV dec-1). For OER, NCP-300 exhibits high activity and durability in alkaline solution. This work highlights the potential of the a-NiCo2O4/NiCoP-300 heterostructure as a promising candidate for OER, thereby providing insights into the development of advanced electrocatalytic applications.