Fe-modified Co₂(OH)₃Cl microspheres for highly efficient oxygen evolution reaction

Surface self-reconstruction by the electrochemical activation is considered as an effective strategy to increase the oxygen evolution reaction (OER) performance of transition metal compounds. Herein, uniform Co₂(OH)₃Cl microspheres are developed and present an activation-enhanced OER performance caused by the etching of lattice Cl⁻ after 500 cyclic voltammetry (CV) cycles. Furthermore, the OER activity of Co₂(OH)₃Cl can be further enhanced after small amounts of Fe modification (Fe²⁺ as precursor). Fe doping into Co₂(OH)₃Cl lattices can make the etching of surface lattice Cl⁻ easier and generate more surface vacancies to absorb oxygen species. Meanwhile, small amounts of Fe modification can result in a moderate surface oxygen adsorption affinity, facilitating the activation of intermediate oxygen species. Consequently, the 10% Fe-Co₂(OH)₃Cl exhibits a superior OER activity with a lower overpotential of 273 mV at 10 mA cm⁻² (after 500 CV cycles) along with an excellent stability as compared with commercial RuO₂. © 2020 Elsevier Inc.