Synthesis and optimization of Mo-Ni-Se@NiSe core-shell nanostructures as efficient and durable electrocatalyst for hydrogen evolution reaction in alkaline media

Synthesis conditions are among the most influential factors in the electrocatalytic prop-erties of the samples studied for the hydrogen evolution reaction (HER). In this study, conditions of NiSe synthesis over a Mo-Ni-Se layer were optimized to create core-shell nanostructures with excellent electrocatalytic properties. To optimize the synthesis con-ditions, first, two electrodeposition techniques in constant potential and pulse potential conditions were investigated and then the optimal temperature for electrodeposition between 5, 25, 40, and 60 degrees C was found. The electrocatalytic activity of the synthesized samples was investigated using linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronopotentiometry tests in a 1 M KOH solution. Preliminary results showed that pulsed electrodeposition of NiSe could improve the electrocatalytic activity of Mo-Ni-Se by forming durable and suitable nano -structures, while electrodeposited NiSe at constant potential could reduce the electro-catalytic activity of the electrode by forming a dense structure. Then, to determine the appropriate temperature, electrodeposition at the optimal pulse potential at four temper-atures of 5, 25, 40, and 60 degrees C was used to synthesize NiSe on Mo-Ni-Se. The final results showed that the sample synthesized at 60 degrees C with an electrochemically active surface area of 2870 cm2 had the highest hydrogen production sites and required only an overpotential of 77 mV to achieve a current density of 10 mA cm-2.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.