Scan Rate Dependent Size and Density-Controlled Deposition of Ni-Co Alloy Particles for Hydrogen Evolution Reaction

Developing a low-cost, abundant, and efficient electrocatalyst is vital for producing clean and sustainable energy. The fabrication of nanostructured Ni-Co alloy electrodes using cyclic voltammetry is reported, and the effect of cyclic voltammetry’s scan rate during deposition on Ni-Co alloys’ structural properties is investigated. The formation of face-centric cubic crystals of Ni-Co alloy is achieved. The size of the crystallites reduces as the scan rate in cyclic voltammetry decrease (from 15 to 1 mV/s). Deposition at a higher scan rate results in spherical particles, while a lower scan rate results in aggregated particles of Ni-Co alloy. The Ni-Co alloy electrode deposited at a scan rate of 1 mV/s exhibits excellent electrocatalytic activity for the hydrogen evolution reaction (HER). This electrode acquires a low absolute value of Tafel slope of − 0.23 V/dec and a low overpotential of − 149 mV vs. RHE at the current density of 10 mA/cm 2 . The higher electrochemical activity of the Ni-Co electrode (deposited at 1 mV/s) is due to the porous morphology and nano-dimensional character of the electrodeposited Ni-Co particles on the surface of the electrode.