Ultra-bubble-repellent sodium perfluorosulfonic acid membrane with a mussel-inspired intermediate layer for high-efficiency chlor-alkali electrolysis

Compromised performance caused by gas product adhesion remains a major challenge for membrane applications in chlor-alkali electrolysis. Here, an ultra-bubble-repellent sodium perfluorosulfonic acid (PFSA-Na) membrane with hierarchical structures of aggregated silica was successfully synthesized by tethering hydrophilic silica onto a mussel-inspired intermediate layer. The surface chemistry, morphology and loading could be controlled via surface tailoring of the silica by γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560). The developed membrane exhibited high hydrophilicity (7.5 ± 1.3°), an ultralow bubble contact area (164.7 ± 2.1°) and negligible bubble adhesion forces (<6 μN) while maintaining efficient NaCl transport and low electric double layer resistance. The superaerophobic-hydrophilic surface enables an excellent cleaning property. When the modified membrane was applied in chlor-alkali electrolysis, the Cl 2 /H 2 gas bubbles were repelled from the membrane surface in time and minimized the negative effects of bubble adhesion, resulting in high-efficiency chlor-alkali electrolysis. Further, the developed membrane exhibited high stability during the continuous 10-h electrolysis process. This result indicates that developing a superaerophobic surface with highly efficient mass transport can lead to high-performance chlor-alkali electrolysis.