Fabrication and characterization of three-dimensional silver nanodomes: Application for alkaline water electrolysis

Abstract

A novel approach to fabricate three-dimensional (3D) silver nanodomes (AgNDs) based on combination of soft lithography and nanosphere lithography was reported. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used for the characterization of the 3D nanostructures. The 3D-AgNDs were evaluated for electrochemical hydrogen production in 6 M KOH solution by some electrochemical techniques. It was found that well-structured AgNDs have higher hydrogen evolution activity than Ag bulk. The hydrogen discharge potential (EH2) at the NDs lowered ∼150 mV with respect to that of the bulk Ag electrode which demonstrated that fabrication of NDs favors the hydrogen evolution kinetics and reduces the energy input for activating the HER. The cathodic Tafel slopes of bulk Ag and AgNDs were found to be 108 and 114 mV dec−1, respectively. The related charge transfer coefficients were very close to 0.5. In the case of AgNDs, resistance was reduced from 660 to 197.1 Ω cm2. This electrode was also characterized with higher current density at a fixed overpotential when compared to bulk Ag. The superior hydrogen evolution performance of AgNDs was assigned to their high roughness and large real surface area. Roughness factor (Rf) of the NDs was 22 times higher than that of bulk Ag. © 2016 Hydrogen Energy Publications LLC