Abstract
This paper demonstrates the improved electrocatalytic behavior of Zn–Ni alloy coatings for alkaline hydrogen evolution reaction (HER), due to addition of TiO2 nanoparticles into the bath. Zn–Ni alloy coatings have been electrodeposited galvanostatically on copper, with wide compositional range (2.31–7.91 wt. % of Zn) at different current densities (c.d.) between 2.0 and 5.0 A dm-2. The electrocatalytic behaviors of all coatings have been studied for alkaline HER in 1.0 M KOH solution, through cyclic voltammetry (CV) and chronopotentiometry (CP) techniques. The electrocatalytic activity of Zn–Ni alloy coatings was found to be in close relation with composition, structure and morphology of the coatings, depending on the c.d. used for deposition. The electrocatalytic activity of Zn–Ni alloy deposited at 3.0 A dm-2 (optimal condition) has been improved further by the addition of TiO2 nanoparticles into the bath. A drastic improvement in the electrocatalytic activity of Zn–Ni alloy coating was observed, due to the incorporation of TiO2 nanoparticles in the alloy matrix. The improved electrocatalytic activity of Zn–Ni–TiO2 coating is attributed to the changed morphology and composition of coatings, confirmed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses. The highest electrocatalytic character of Zn–Ni–TiO2 composite coating, under optimal deposition condition, is attributed to the increased porosity and electroactive centers, affected due to TiO2 nanoparticles addition, and experimental results are discussed. Keywords: effect of TiO2, electrocatalysis, improved HER, SEM, Zn–Ni alloy
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