A ZrO2-PSU composite membrane reactor for simultaneous Cl2 and H2/NaOH production via chlor-alkali electrolysis

A ZrO 2 -PSU composite membrane with asymmetric structure was developed for chlor-alkali electrolysis. • ZrO 2 addition enhanced hydrophilicity and reduced area resistance but lowered bubble point pressure. • The membrane reactor achieved high Faradaic efficiencies (>96% for HER and > 98% for CER) with considerable NaOH yield. • The zero-gap electrolyzer delivered 3.33 V at 100 mA cm −2 over 20 h with robust structural and chemical stability. The chlor-alkali process is a vital industrial route for the production of chlorine (Cl 2 ), hydrogen (H 2 ), and sodium hydroxide (NaOH). However, conventional ion-exchange membrane-based technologies face challenges related to high cost, limited durability, and susceptibility to fouling and degradation under harsh operating conditions. Here, we report a zirconium dioxide-polysulfone (ZrO 2 -PSU) composite membrane reactor that enables simultaneous and efficient Cl 2 and H 2 /NaOH production via chlor-alkali electrolysis. The composite membrane, fabricated via phase inversion tape casting, integrates ZrO 2 nanoparticles into a porous PSU matrix, achieving a well-defined asymmetric structure with a dense top layer and a finger-like porous bottom layer. The optimized composite membrane ( Z -PSU-70) exhibits lowest area resistance, enhanced hydrophilicity, and effective gas barrier properties. In an H-type electrolysis cell using a nickel mesh cathode and a RuO 2 @carbon paper anode, the reactor delivers stable cell voltages and high Faradaic efficiencies (>96% for H 2 and > 98% for Cl 2 ) with minimal gas crossover. Furthermore, a zero-gap flow cell configuration achieves a low cell voltage of approximately 3.33  V at 100 mA cm −2 , with stable performance over 20 h. Post-electrolysis characterizations confirm the structural and chemical stability of both the membrane and electrodes. This work presents a cost-effective and high-performance membrane reactor design, offering a promising pathway toward more sustainable and efficient chlor-alkali electrolysis.