Bimetallic Cobalt-Nickel Electrode Made by a Sputtering Technique for Electrocatalytic Hydrogen Evolution Reaction: Effect of Nickel Ratios

Electrocatalytic hydrogen evolution reaction (HER), a half-reaction of water splitting, is highly important to be developed for green and sustainable hydrogen production. In this work, a bimetallic cobalt-nickel (CoNix) alloy is deposited on nickel foam with a home-made target by using a radio frequency (RF) magnetron sputtering technique at a low deposition temperature. The as-sputtered CoNix was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy to evaluate its physical and chemical properties. The electrochemical measurement exhibited that the bimetallic CoNix alloy had a promising performance for HER in alkaline solutions. CoNi4, as the optimum ratio, possessed low overpotentials of 53 and 175 mV to achieve current densities of 10 and 100 mA/cm(2), respectively. Moreover, among the as-sputtered CoNix, CoNi4 had the largest electrochemical surface-active area (485 cm(2)) and the lowest electron-transfer resistance (1.14 omega). CoNi4 was also quite stable under the continuous operation of constant current densities of 10 and 50 mA/cm(2) for 20 h. This work is based on the RF magnetron sputtering technique for developing bimetallic CoNix alloy as an efficient HER catalyst for electrochemical energy.

Automated summary

In this study, a bimetallic CoNix alloy was prepared using a radio frequency magnetron sputtering technique and exhibited promising performance for electrocatalytic hydrogen evolution reaction (HER) in alkaline solutions. The optimized CoNi4 ratio showed low overpotentials and high current densities, with a large electrochemical surface area and low electron-transfer resistance. This work provides a foundation for developing bimetallic CoNix alloys as efficient HER catalysts for electrochemical energy.