Effect and Mechanism of Cu Foams with Different Porosity on Kinetic Parameters of Ga Electrodeposition: Accompanied by Hydrogen Evolution Reaction

Abstract

The process of Ga electrodeposition is usually accompanied by intense hydrogen evolution reaction, so the escape rate of hydrogen bubbles from the electrode surface has a great influence on Ga electrodeposition. Here, Cu foams with different porosity were applied to study the effect of the escape rate of hydrogen bubbles on Ga electrodeposition. When Ga electrodeposition is controlled by mass transport process, Cu foams with high porosity exhibit a higher reaction rate of Ga electrodeposition because of their faster bubble escape rate. The larger pore channel diameter of Cu foam with low porosity reduces the escape rate of hydrogen bubbles and hinders the mass transfer process. The addition of surfactant accelerates the escape rate of bubbles from the electrode surface, thus promoting the mass transfer process and leading to an increase in the current efficiency of Ga electrodeposition. It is also found that the process of Ga electrodeposition is controlled by nucleation rate at the early stage. Due to the rapid separation of hydrogen bubbles, Cu foams with high porosity provide more effective sites per unit surface area. Therefore, Cu foams with high porosity have a higher nucleation rate and a lower induced time for Ga electrodeposition.