Interface Engineering of Oxygen-Vacancy-Rich NiCo2O4/NiCoP Heterostructure as an Efficient Bifunctional Electrocatalyst for Overall Water-Splitting

Low-cost bifunctional electrocatalysts towards oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is highly desirable in the perspective of for energy evolution.Herein, we report a novel and high-efficiency bifunctional electrocatalyst via interface engineering inside NiCo2O4/NiCoP heterostructure. Such interface-modulated strategy can significantly facilitate the generation of rich oxygen vacancies and also enrich active sites at the boundary of the prepared NiCo2O4/NiCoP heterostructure, leading to favorable electronic structure and fast charge-transfer capacity. For the OER, the NiCo2O4/NiCoP heterostructure exhibits an extremely low overpotential of about 295 mV at 10 mA cm−2, which is much better than that of pristine counterparts. Impressively, low overpotential of about 198 mV at 10 mA cm−2 can meet the need for HER for this heterostructure in alkaline media. Furthermore, overall water-splitting can be realized through the NiCo2O4/NiCoP heterostructure as the cathode and anode simultaneously with a cell voltage of only 1.66 V to drive 10 mA cm−2. This work provides a promising interface-regulated strategy to realize transition metal heterostructure as efficient electrocatalysts in energy-related applications.