Enhancement of electrocatalytic efficiency by rapid bubble detachment at electrodeposited feather-like FeCoNiCuMn high-entropy alloy porous structure

Abstract

Efficient and stable electrocatalysts are crucial for efficient hydrogen energy production. The rapid detachment of bubbles is an important factor influencing continuous and efficient catalysis. In this study, a unique three-dimensional porous structure was constructed by electrodeposition method to avoid the influence of bubble adhesion on the catalyst. High entropy alloys (HEAs) with porous structures are rich in active sites and thus have excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performances. By controlling the deposition current and time, the microstructure of the HEA presents a feather-like shape, with strong hydrophilicity and rapid bubble release behavior, exposing more active sites and facilitating bubble convergence. The porous structure HEAs provide gas transport channels, creating favorable conditions for rapid bubble detachment. The prepared FeCoNiCuMn HEAs exhibit the overpotentials of 251 mV for the OER and 200 mV for the HER at a current density of 100 mA cm⁻² in an alkaline solution, and the corresponding Tafel slopes are 47.93 mV dec⁻¹ and 40.42 mV dec⁻¹, respectively. As the cathode and anode of the electrolyzer, it could achieve a current density of 100 mA cm⁻² with a voltage of only 1.75 V. Furthermore, the HEAs show good stability with almost no loss of activity after long-term cycling of 30 h. These results strongly suggest that the rapid detachment of bubbles is contributing to the performance of electrolyzed water. This study provides a feasible approach to enhance the electrocatalytic efficiency and address the bubble detachment issue in the water electrolysis process.