Morphological variation of electrodeposited nanostructured Ni-Co alloy electrodes and their property for hydrogen evolution reaction

Nanostructured nickel-cobalt alloys of the content of Co varying from 0% to 75% for hydrogen evolution reaction were fabricated by galvanostatic electrochemical deposition processes. With the incorporation of Co into Ni matrix, the morphologies of Ni-Co alloys are changed from nanocones to lamellar structure and finally evolved to a mixed shape of nanocone structure and lamellar structure. Among these Ni-Co alloys, the optimal Ni-60% Co alloy exhibits outstanding electrocatalytic activity with a small hydrogen overpotential of -180 mV and follows Volmer-Tafel mechanism. Better performance of Ni-60%Co can be attributed to the synergetic combination of Ni and Co and unique complex mesh structure which provides the enlarged exposure of catalytically active sites. In addition, Ni-60%Co alloy also displays good electrochemical stability under 10 h galvanostatic test. With prominent electrochemical properties, Ni-60%Co alloy has a certain advantage in the catalytic hydrogen evolution material. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.