Effects of ultrasonic field on structure evolution of Ni film electrodeposited by bubble template method for hydrogen evolution electrocatalysis

Self-supporting porous Ni film with uniform honeycomb-like micropores and a thickness of up to 66 mu m is electrodeposited by dynamic hydrogen bubble template (DHBT) method in ultrasonic field. The dependence of ultrasonic power on porous structure and thickness of Ni films is investigated. The porous structure evolution mechanism is analyzed in terms of the effects of ultrasonic field on hydrogen evolution reaction (HER) and metal electrocrystallization. The HER catalytic performance of porous Ni films with different structure has also been studied. The results indicate that due to the acoustic cavitation and impact effect of ultrasonic waves, the nucleation of hydrogen bubble and the separation of hydrogen bubble from the electrode surface are improved, and the HER is enhanced. Then, self-supporting porous Ni film with uniform honeycomb-like micropores is formed. Too fast bubble separation is not conducive to the formation of porous structure. Moreover, in ultrasonic field, the current efficiency of Ni electrodeposition is increased owing to the enhanced mass transfer by ultrasonic-induced convection and hydrogen bubble agitation convection. Consequently, the thickness of porous Ni film is up to 66 - 89 mu m. The porous Ni film electrodeposited in ultrasonic field with power of 250 W exhibits excellent HER catalytic performance due to the large activity area. Meanwhile, all the self-supporting Ni films possess a good long-term stability.

Automated summary

The study investigated the effect of ultrasonic power on the porous structure and thickness of Ni films, revealing that ultrasonic field can improve the nucleation and separation of hydrogen bubbles, enhancing the HER catalytic performance and forming Ni films with uniform micropores.