Electrocatalytic gas evolution reactions, where gaseous molecules are electrogenerated by reduction or oxidation of a species, play a central role in many energy conversion processes and industries. Exploration of gas bubble behavior such as nucleation and removal from the electrode surface is an important aspect in electrochemical gas evolution reaction. Superaerophobic electrode, usually constructed by their surface micro- and nano-structure, have demonstrated excellent performance for gas-evolution electrochemical reaction due to the bubble-repellent properties. In this study, we carried out nanoscale electrochemical measurement and visualization of gas bubble nucleation and dynamics at the nanostructured catalyst electrode using a novel scanning electrochemical cell microscopy (SECCM) technique. Classic Pt film and non-conventional transition metal dicochogenide MoS₂ with different surface topologies were employed as the substrate for various gas (H₂, N₂ and O₂) bubble electrochemical study. Interestingly, the nanostructured catalyst surface exhibit a significantly less energy barrier for gas (H₂, N₂, and O₂) bubble nucleation compared to the flat counterpart. Electrochemical mapping across electrode surface with different architecture shows no correlation with HER activity. Our work demonstrate the first electrochemical mapping of gas bubbles across the transition metal dicochogenide material catalyst. The results reveal the intrinsic structure-properties relationship and offers insightful view for electrocatalytic gas evolution in clean energy technology.

Yulong Liu

Appearances