Iron and nickel co-doped cobalt hydroxide nanosheets with enhanced activity for oxygen evolution reaction

Abstract

A poor oxygen evolution reaction (OER) activity restricts the efficiency of large scale H₂ production from water splitting. Developing highly active, low cost and lasting electrocatalysts has become a top priority. Herein, we have successfully synthesized iron and nickel co-doped cobalt hydroxide (Co–Ni–Fe₅₁₁) nanosheets for the OER. This catalyst exhibits outstanding performance with an overpotential of 288 mV at a current density of 10 mA cm⁻², a high polarization current of about 67 mA cm⁻² at 330 mV overpotential, a low Tafel slope of 43 mV dec⁻¹, and small degradation after 8 hours of long-term OER operation. In addition, we simulate alkaline water electrolysis at a current density of 200 mA cm⁻² at 70 °C in 6 M KOH electrolyte, and the energy consumption of Co–Ni–Fe₅₁₁ is 45.7 kW h kg_H2⁻¹. For comparison, commercial RuO₂ consumed 46.8 kW h kg_H2⁻¹. This suggests that Co–Ni–Fe₅₁₁ is more appropriate than commercial RuO₂ for water electrolysis in commercial water electrolysis. The high activity, low Tafel slope, good stability and low energy consumption will pave the way for the use of Co–Ni–Fe₅₁₁ in practical applications.