Highly efficient and durable water oxidation in a near-neutral carbonate electrolyte electrocatalyzed by a core-shell structured NiO@Ni-Ci nanosheet array

The development of cost-effective and high-performance water oxidation electrocatalysts operating in carbonate (Ci) electrolytes is highly desired but still remains a great challenge. In this communication, we report the in situ electrochemical development of an amorphous Ni-Ci layer on a NiO nanosheet array supported on carbon cloth (NiO@Ni-Ci/CC) as a 3D catalyst electrode for water oxidation in 1.0 M KHCO3 (pH: 8.3). To drive a geometrical catalytic current density of 15 mA cm(-2), such core-shell structured NiO@NiCi/CC only demands an overpotential of 387 mV, with its catalytic activity being maintained for at least 25 h. And at an overpotential of 500 mV, this catalyst electrode achieves a high turnover frequency of 0.18 mol O-2 per s.