Cobalt (oxy)hydroxide nanosheet arrays with exceptional porosity and rich defects as a highly efficient oxygen evolution electrocatalyst under neutral conditions

Abstract

An oxidation-mediated defect and porosity enrichment strategy is developed for the synthesis of a new electrocatalyst consisting of cobalt (oxy)hydroxide nanosheet arrays (denoted as CoO_xH_y NSAs) grown on carbon cloth (CC), which feature a 3D hierarchical nanostructure with exceptional porosity and rich defects. The CoO_xH_y/CC shows exceptional activity and stability for the oxygen evolution reaction under neutral conditions, as indicated by its high current density of 38 mA cm⁻² at 1.8 V, small Tafel slope of 121 mV dec⁻¹, low overpotential of 430 mV, and 24 h durability at 10 mA cm⁻² in 0.1 M phosphate buffer solution (PBS).