Experimental and theoretical study on hydrogen production by using Ag nanoparticle-decorated graphite/Ni cathode

Abstract

In this study, graphite (G) electrode was coated with nickel and decorated with silver nanoparticles (G/Ni/Ag) with the help of galvanostatic method, and electrodes were used as a cathode in alkaline water electrolysis system. The characterization was achieved using X-ray diffraction and field emission scanning electron microscopy. Hydrogen evolution performance of electrodes was investigated via cyclic voltammetry, chronoamperometry, cathodic polarization curves, and electrochemical impedance measurements. Electrochemical results showed that hydrogen production efficiency significantly increased and charge transfer resistance decreased via G/Ni/Ag. The electrochemical water splitting performance of G/Ni/Ag, was established in a joint experimental and computational effort. Water and proton adsorption on Ag-decorated Ni surface were investigated using density functional theory. Electronic structure calculations identified the role of Ag adatom and Ni surface on water and proton adsorptions. From the computational studies, O in water was more reliable to adsorb at the bridge position of the Ag and Ni atoms, leading improved orbital overlap between H and Ni atoms and maximized chemical and physical interactions between the H2O molecules. Therefore, the Ag-decorated Ni(111) surface provides preferable adsorption site for the O atom in water and direct interactions between water Hs and available surface Ni atoms promote water dissociation.