Facile synthesis of binary NiCoS nanorods supported on nickel foam as efficient electrocatalysts for oxygen evolution reaction

A facile two-step method has been applied to synthesize novel binary metal NiCoS nanorods supported on nickel foam (NF) as electrocatalysts for oxygen evolution reaction (OER). Firstly, electrodeposition process is conducted to fabricate binary Ni-Co hydroxides on NF (NiCo/NF). Then, a hydrothermal sulfuration of NiCo/NF has been adopted to prepare NiCoS nanorods arrays uniformly grown on the surface of NF (NiCoS/NF). XRD indicates that NiCoS/NF has mixed crystal phases of Ni3S2, CoS and Co9S8. SEM images display the uniform NiCoS nanorods composed of many vertical nanosheets on the surface, implying more exposed active sites. OER measurements demonstrate that NiCoS/NF has better activity with an overpotential of 370 mV to reach 100 mA cm−2 than NiCo/NF and CoSx/NF. Electrochemical impedance spectroscopy (EIS) tests confirm the faster charge-transfer rate of NiCoS/NF and smaller Tafel slope derived from binary NiCoS, implying the excellent electrocatalytic performances of binary metal sulfides.