Nitrogen doped and carbon coated CoP hollow nanospheres with enhanced electrocatalytic activity towards the oxygen evolution reaction

Abstract

The oxygen evolution reaction (OER) is involved in various renewable energy systems, such as water-splitting cells and metal–air batteries. Cobalt phosphide nanomaterials have been reported as promising OER electrocatalysts. Herein, the rational design of advanced nanostructures for nitrogen doped and carbon coated cobalt phosphide hollow nanospheres (CoP@NC HNS) was highly desirable to optimize their electrocatalytic performance. SiO₂ nanospheres were used as a sacrificial template for the synthesis of hollow nanospheres composed of ultrathin CoP@NC nanosheet arrays. The hollow nanostructure CoP@NC was coated with a layer of carbon material and the thickness of the shell was about 40 nm. The resultant CoP@NC HNS manifested high electrocatalytic activity towards the OER with low overpotential (320 mV, 10 mA cm⁻²), small Tafel slope (68 mV dec⁻¹), and remarkable stability in alkaline electrolyte. Remarkably, the CoP@NC HNS still maintained an outstanding performance for the OER at 60 °C.