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 gamma-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560). The developed membrane exhibited high hydrophilicity (7.5 +/- 1.3 degrees), an ultralow bubble contact area (164.7 +/- 2.1 degrees) and negligible bubble adhesion forces (<6 mu N) while maintaining efficient NaCl transport and low electric double layer resistance. The superaemphobic-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.