Ni-Doped CuS as an efficient electrocatalyst for the oxygen evolution reaction

It remains a challenge to find efficient inexpensive electrocatalystsfor the oxygen evolutionreaction (OER), which plays a central role in several electrochemical energy conversiontechnologies. Herein, we report the synthesis of pure CuS nanocrystals, mostly having a hexagonal plate shape, and Ni-doped CuS using a solvothermal technique at 150 °C for 8 h. Ni-Doping is demonstrated to drastically improve the OER activity of CuS and is found to be a highly effective OER catalyst in alkaline medium. Among the doped samples, 3% Ni-doped CuS nanocrystals exhibited a small overpotentialof 390 mV to achieve a current density of 10 mA cm−2 and a Tafel slope of 96.8 mV dec−1, better than that of undoped CuS and standard IrO2. The same catalyst maintained OER stability with 88% current density retention after 10 h.