Preparation of hydrogen evolution electrode from nickel slag: Crystal surface modulation and selective growth

Hydrogen production from electrolytic water is a key component in realising a hydrogen economy. At the same time, resourceful utilization of nickel slag can reduce environmental and health hazards. The aim of this study is to prepare clean and efficient hydrogen evolution electrodes from nickel slag by modulating the crystal surface of electrolytic catalyst. According to the density functional theory calculations, the crystal surface with the best catalytic properties is Ni (111). Based on the theoretical calculations, this work proposed controlling the reduction order and reduction efficiency of Ni²⁺ and H₂O in the nickel slag leachate during electrolysis to modulation of crystal surface growth of Ni. Moreover, amorphous Ni(OH)₂ was designed to selectively grow in Ni product to further improve the catalytic performance of Ni (1 1 1). The electrodes with the best catalytic performance for hydrogen evolution were obtained when the electrodeposition conditions were 30 min, 0.05 M, and 12.5 mA/cm². A current density of 10 mA/cm² was achieved with an overpotential of only 17.46 mV. The Tafel slope was 31.2 mV·dec⁻¹. The proposed method is a straightforward and clean approach that does not require membrane addition. At the same time, using nickel slag as raw material can not only reduce the harm of nickel slag to the environment, but also reduce the cost of preparing electrodes. Therefore, this method offers an efficient, environmentally friendly, and cost-effective approach to preparing high-performance catalytic electrodes for hydrogen evolution.