Effectively enhanced activity for overall water splitting through interfacially strong P-Co-O tetrahedral coupling interaction on CoO/CoP heterostructure hollow-nanoneedles

Designing electrocatalysts reasonably is of significant importance for the sustainable development of energy conversion. However, designing active sites at the surface interface to enhance catalytic activity has been an enormous challenge. In this study we fabricated hollow-nanoneedles with a hierarchical cobalt oxide/phosphide heterostructure attached to nitrogen-doped carbon (hereinafter CoO/CoP-NC) via induced oxidation/phosphating surface-interface reconfiguration engineering. CoO/CoP-NC shows overpotentials of 178 mV and 268 mV toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at 10 mA cm⁻², respectively. DFT calculation was used to establish that the interfacial P-Co-O tetrahedral coupling promotes rapid charge transfer, optimizes the electronic structure, and lowers the d-band center. This is expected to accelerate the exposure of active sites and the transformation of adsorption energy to significantly improve the electrochemical reaction activity and reaction kinetics. The assembled double electrode battery shows a low cell voltage of 1.53 V at 10 mA cm⁻² and excellent durability. The proposed design provides a promising strategy for synthesizing noble metal-free catalysts to enhance the performance of electrocatalysts through surface-interface reconfiguration engineering.