Hydrogen evolution reaction in alkaline media on Ni-S-Co electrode with hierarchical morphology prepared by gradient electrodeposition

In this study, Ni-S-Co electrode with the microstructure of multi-channel coral-forest morphology was prepared by gradient electrodeposition. The composition of deposits was determined by XRD and XPS; the structure was characterized by SEM, TEM and EDS; the electrochemical performance and stability of Ni-S-Co electrode were studied by LSV, CV and EIS in 1 M KOH solution. Through investigating the electrode surface micromorphology and composition and evaluating various electrochemical properties of the electrode, it can be confirmed that, because of the employment of gradient electrodeposition method and the addition of Co element, the Ni-S-Co electrode surface contents was amorphous and doped with a small amount of crystalline sulfide to accelerate the efficiency of electron transfer, it also has hierarchical structure to facilitate hydrogen and electrolyte transfer. Particularly, the electrochemical surface area (ECSA) of Ni-S-Co deposits was 38405 cm(2), which was extremely higher among all other reported electrodes. Moreover, Ni-S-Co deposits only requires an overpotentials of 211 mV vs. RHE to achieve a current density of 100 mA cm(-2). Finally, after electrochemical stability test for 5000 cycles of CV test, the electrocatalytic properties did not decrease considerably at all, but got improved slightly. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.