Hierarchical micro/nanostructured C doped Co/Co3O4 hollow spheres derived from PS@Co(OH)2 for the oxygen evolution reaction

Abstract

Hierarchical micro/nanostructured C doped Co/Co₃O₄ hollow spheres were prepared by two-step treatment (annealing at 600 °C in an Ar atmosphere and then at 250 °C in air) of PS@Co(OH)₂ core–shell structures templated from PS microspheres without any modification. In 1 M KOH, such hollow nanospheres showed an overpotential of 352 mV at a benchmark oxygen evolution reaction (OER) current density of 10 mA cm⁻², which was lower than that of RuO₂ (364 mV), Co₃O₄ hollow nanospheres (410 mV) and C-Co/Co₃O₄ nanoparticles (462 mV). Importantly, the C-Co/Co₃O₄ hollow spheres exhibited a small onset potential (1.49 V) due to their more active sites, higher electrical conductivity, larger specific surface area, and excellent electron and ion diffusion permeability. This work provides a strategy to design and fabricate earth-abundant, low-cost electrocatalysts for water splitting in practical applications.