Electrodeposited Ni-W-Zn Alloys as Promising Electrocatalysts for Hydrogen Production by Micro-Anode Guided Electroplating

The aim of this study is to identify effective, durable, and affordable electrocatalysts that can replace Pt-group metals during the hydrogen evolution reaction (HER) in alkaline water electrolysis. To achieve this, a range of Ni-W-Zn alloys were prepared using the micro-anode guided electroplating (MAGE) process. The bath ratio of [Ni2+] / [WO42-] / [Zn2+] was systematically varied during the experiment. To characterize the micropillars, three-dimensional micropillars composed of Ni-based material were fabricated and analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The results showed that the micropillars had a smooth morphology and were composed of an amorphous phase with a composition range of 54-61 at. % Wand 3-9 at. % Zn. The electrocatalytic activity of the micropillars was assessed in a solution of 1.0 M KOH using various electrochemical techniques, such as Tafel polarization, linear scanning voltammetry (LSV), and cyclic voltammetry (CV). The micropillars' morphology and composition were found to have a significant impact on their catalytic efficacy. The Ni50W41Zn9 composition yielded the most effective catalytic performance, as reflected by the highest exchange current density of 2 mA/cm2, the lowest Tafel slope of 73 mV/dec, and the maximum current density of 742.61 ma/ at the 650th cycle as determined by CV. The superior catalytic reactivity of the 3D Ni-W-Zn alloy compared to the unmodified Ni electrode can be attributed to two factors: the activation of the hydrogen adsorption-desorption process (facilitated by the presence of W on the Ni-W surface), and the enlargement of the surface area resulting from the formation of pores due to dezincification in the alkaline environment.