Recent progress of enhanced bubble separation in alkaline water electrolyzer

Alkaline water electrolysis has a large industrial application and development potential in hydrogen energy owing to its high maturity and low cost. However, its moderate energy efficiency, especially caused by bubble effects, inhibits its use for large-scale hydrogen production. To overcome this shortcoming, this review first analyzes the bubble effect and summarizes the external operation methods, such as external field intensification, flow operation, fluctuation operation, and surfactant addition to the electrolyte, to enhance bubble separation in the electrolyzer. Then, electrode and flow channel structure optimization, particularly superhydrophilic and superaerophobic electrodes, and flow channels with varying heights, square column arrangements, and inlet/outlet numbers are highlighted. Finally, future research directions in alkaline water electrolysis technology are suggested to advance the industrial application of large-scale alkaline water electrolysis.