Rational introduction of borate and phosphate ions on NiCo2O4 surface for high-efficiency overall water splitting

Abstract The design of efficient bifunctional electrocatalysts for overall water splitting is an essential task for the production of hydrogen. In this work, NiCo2O4 is modified by the introduction of borate and phosphate ions for high-efficiency water splitting performance. The modified NiCo2O4 shows excellent performance towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with the small overpotential at 10 mA cm−2 of 130 mV and 240 mV, respectively, served as the anode and cathode, which requires a cell voltage of 1.65 V to reach the current density of 10 mA cm−2. The excellent electrocatalytic performance is mainly attributed to surface modification, rational adjustment of the electronic structure of active sites to increase the intrinsic activity of NiCo2O4. Owing to its excellent performance, the modified NiCo2O4 can be a promising bifunctional electrocatalyst for overall water splitting, the surface-modified method is also a promising technology to modify more electrocatalyst surface for excellent electrochemistry performance.