Bubble management in PEM water electrolysis via imprinting patterned grooves on catalyst layer

The demand for cost reduction in proton exchange membrane water electrolyzer (PEMWE) is driving it to increase the operating current density and higher current densities require better bubble management. In this work, we demonstrate that introducing patterned grooves to the catalyst layer surface (CL) is able to enhance the bubble evolution and improve electrolyzer performance. The patterned grooves microstructure on CL provides additional bubble nucleation sites and faster bubble evolution. Smaller average bubble size and higher bubble detachment frequency during water electrolysis are observed through a bubble evolution visualization system and further confirmed by a frequency analysis method. In addition, patterned grooves also improve the hydrophilicity and aerophobicity of CL surfaces. In the PEM water electrolyzer cell, the patterned grooves on CL boost the cell performance and reach high current densities up to 5.0 A cm-2. With better bubble management, patterned grooves significantly reduce the mass transport overpotential at each current density. At 5.0 A cm-2, the mass transport overpotential is reduced by 59%. This work provides a new idea of bubble management in PEMWE and is highly informative for designing CLs for PEMWE and other gas-evolving electrochemical energy conversion applications.