Amorphous Nickel-Cobalt-Borate Nanosheet Arrays for Efficient and Durable Water Oxidation Electrocatalysis under Near-Neutral Conditions.

Electrolytic hydrogen generation needs earth-abundant oxygen evolution reaction electrocatalysts that perform efficiently at mild pH. Here, the development of amorphous nickel-cobalt-borate nanosheet arrays on macroporous nickel foam (NiCo-Bi/NF) as a 3D catalyst electrode for high-performance water oxidation in near-neutral media is reported. To drive a current density of 10 mA cm , the resulting NiCo-Bi/NF demands an overpotential of only 430 mV in 0.1 m potassium borate (K-Bi, pH 9.2). Moreover, it also shows long-term electrochemical durability with maintenance of catalytic activity for 20 h, achieving a high turnover frequency of 0.21 s at an overpotential of 550 mV.