Electrodeposition of Iridium-Nickel Thin Films on Copper Foam: Effects of Loading and Solution Temperature on HER Performance of Electrocatalyst in Alkaline Water

Abstract

Developing novel hydrogen evolution reaction (HER) catalysts with high activity, high stability and low cost is of great importance for the applications of hydrogen energy. In this work, iridium-nickel (Ir-Ni) thin films were electrodeposited on a copper foam as electrocatalyst for HER, and electrodeposition mechanism of Ir-Ni film was studied. The morphology and chemical composition of thin films were determined by scanning electron microscopy and energy-dispersive spectroscopy, respectively. The electrocatalytic performances of the films were estimated by linear sweep voltammograms, electrochemical impedance spectroscopy and cyclic voltammetry. The results show that Ir-Ni thin films were attached to the substrate of porous structure and hollow topography. The deposition of Ni was preferable in the electrolyte without the addition of additives, and Ir-Ni thin film was alloyed, resulting in high deposition rate for Ir42Ni58 thin film, and subsequently an increase of Ir content in the thin films of Ir80Ni20 and Ir88Ni12. Ir-Ni thin films with Tafel slopes of 40-49 mV·dec-1 exhibited highly efficient electrocatalytic activity for HER. The electrocatalytic activity of Ir-Ni thin films showed a loading dependence. As the solution temperature raised from 20 oC to 60 oC, the hydrogen evolution performance of Ir-Ni thin films improved. The apparent activation energy value of Ir88Ni12 film was 7.1 kJ·mol-1. Long-term hydrogen evolution tests exhibited excellent electrocatalystic stability in alkaline solution.