Superaerophobic Polyethyleneimine Hydrogels for Improving Electrochemical Hydrogen Production by Promoting Bubble Detachment

Abstract Removal of gas bubbles from the electrode surface is practically important to maintain the activity of electrochemical gas evolution reactions. Conventionally, most studies have focused on the development of electrocatalysts and paid less attention to the bubble removal issues. Recently, it has been reported that attached gas bubbles can be readily eliminated by imparting extremely gas‐repellent properties (so‐called superaerophobicity) to electrodes via controlling their nano/microstructure. However, this approach is material‐specific and requires harsh and expensive synthetic conditions, causing difficulties in scaling up to large‐area electrodes for commercialization. To address these issues, a universal method to impart superaerophobicity to various electrodes through simple coating with porous polymeric hydrogels without affecting the underlying target substrates is reported. The modification of electrodes with superaerophobic polymeric hydrogel substantially enhances the efficiency of the hydrogen evolution reaction because the hydrogel can facilitate the removal of as‐generated gas bubbles and thereby minimize ohmic and concentration overpotentials. Particularly, electrodes modified with the superaerophobic hydrogel outperform those modified with electrocatalysts at high current densities where more gas bubbles are generated and adhered to. The results provide insights into the design of various electrochemical devices that are based on gas‐involving reactions.