Core-Shell-Structured NiS2@Ni-Bi Nanoarray for Efficient Water Oxidation at Near-Neutral pH

The development of high-performance and cost-effective water oxidation catalysts operating under mild conditions is attractive for the conversion of electricity into chemical fuels. In this communication, we report the in situ electrochemical development of a Ni-B-i layer (5-8 nm thick) on a NiS2 nanoarray supported on carbon cloth (i.e., NiS2@Ni-B-i/CC) for efficient water oxidation in 0.1M potassium borate electrolyte at pH 9.2. As a durable 3D catalyst electrode, core-shell-structured NiS2@Ni-B-i/CC shows excellent catalytic activity for water oxidation and approaches a geometrical catalytic current density of 20 mAcm(-2) at an overpotential of 486 mV, with long-term electrochemical stability for at least 24 h with a high turnover frequency of 0.28 mol O-2 s(-1) at an overpotential of 500 mV and nearly 100% Faradic efficiency for oxygen evolution.