Prior oxidation of Ni substrates increases the number of active sites in Ni3S2 obtained by sulfidation and enhances its multifunctional electrocatalytic activity

Abstract

An unconventional method of improving the electrochemically accessible number of sites (ECASs) in a nickel sulphide catalyst has been developed. The unconventional method assisted enhancement in the ECAS of Ni led to an exceptional electrocatalytic performance of the overall electrode featuring Ni, S, and O mainly as constituent elements. The electrocatalytic activity of this ECAS-enhanced anode was screened for the oxidation of water, glucose, methanol, and hydrazine, and it was found to outperform the state-of-the-art catalysts. When an asymmetric electrolyzer consisting of a Pt/C cathode and the ECAS improved Ni₃S₂–O/Ni anode was made and deployed for the co-electrolysis of water with these small molecules (methanol, glucose, and hydrazine), the cell voltages at −10 mA cm⁻² for H₂ production were reduced by 230, 340, and 1000 mV, respectively, in comparison with the conventional electrolysis carried out with only 1.0 M KOH. Since co-electrolysis of small molecules with water is now accepted to be an energy-saving way of producing H₂ fuel, the unconventional development of this ECAS-improved Ni₃S₂–O/Ni multifunctional anode brightens the prospects for the scale-up of water–methanol/glucose/hydrazine electrolyzers and efficient production of H₂.