Hydrogen evolution kinetics on Ni cathodes modified by spontaneous deposition of Ag or Cu

Abstract

Nickel modification by spontaneous deposition of transition metals such as Ag and Cu is shown as an economic and simple alternative for the activation of hydrogen evolution reaction (HER) on cathodes in alkaline media. The kinetics of HER is studied on Ni/Ag and Ni/Cu catalysts by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) using a rotating disk electrode (RDE). Freshly synthesized catalysts, as well as catalysts subjected to a short chronoamperometric ageing procedure, are analyzed and the kinetic and thermodynamic parameters of the HER are obtained. The nickel surface modified with transition metals with an outer shell electronic configuration [xd10(x+1)s1], such as Cu (3d104s1) and Ag (4d105s1), shows an improved activity for the HER compared to bare nickel. Furthermore, the Ni/Cu catalyst presents a decreased onset potential. The hydrogen evolution rate, measured as current density at –1.5 V (vs. SCE), is similar on Ni/Cu and Ni/Ag electrodes.