Analysis of the effect of surface wettability on hydrogen evolution reaction in water electrolysis using micro-patterned electrodes

Abstract

The hydrogen evolution reaction (HER) was investigated using Ni catalytic electrodes with micro-patterned surfaces. The present aim was to correlate HER efficiency with the surface wettability of Ni cathodes produced with different micropatterns. Regular Ni microdot arrays, 5–10 μm in diameter, 5–10 μm in pitch were fabricated on a 7 mm diameter Cu substrate and tested in alkaline water electrolysis (AWE) experiments. Using electrodes of this design, it may be possible to relate the electrochemical reaction kinetics to the electrolyte wettability localized to the microdot surface area. The surface microstructures of the electrode considerably influenced the reaction efficiency of the HER during alkaline water electrolysis at −20 mA cm−2. Furthermore, in situ video observations of the electrode surface during the HER revealed that the bubble size increased when the surface wettability of the electrodes was decreased. That is, the surface texture (micro-patterns) affected the HER efficiency by influencing bubble evolution and aggregation behavior. This observation may aid in the design of highly efficient HER catalytic electrodes. Keywords: Hydrogen evolution reaction (HER), Micro-patterned electrode, Surface wettability, Alkaline water electrolysis