Zirfon Functionalization for Gas Crossover Mitigation in Alkaline Water Electrolysis

Liquid alkaline water electrolyzer (LAWE) has been invented and deployed for decades for high-purity hydrogen production, accounting for more than 60% of the water electrolysis market globally. The modern zero-gap LAWE system features a porous medium serving as the separator to divide the anode and cathode electrodes in the electrode assembly, which also transports electrolytes between the two sides. Due to durability concern of most ion-conducting polymers under harsh conditions of 80℃ and 30% KOH, the most widely used separator is Zirfon diaphragm, which is comprised of a polysulfone matrix and zirconia powder. A typical Zirfon diaphragm has a thickness of ~220 or 500 microns. Therefore, hydrogen produced on the cathode side will crossover through porous Zirfon diaphragm and mix with oxygen produced on the anode side. Hence, a safety concern will arise from the mixing of hydrogen and oxygen, potentially forming flammable mixtures when the hydrogen content is above flammable limit. To mitigate this safety issue, we developed a strategy to preferentially load a low loading of catalyst nanoparticles on Zirfon diaphragm. The loaded catalyst nanoparticles serve as the gas recombination catalyst (GRC), catalyzing the recombination reaction of hydrogen and oxygen to form water. Therefore, this strategy provides a solution to consume the crossing-over hydrogen, thereby reducing the hydrogen content on the anode side and mitigating safety concerns. In this work, we provided the structural characterization of the developed GRC, assessed the cell performance, and demonstrated the gas recombination efficacy by detecting hydrogen crossover after applying GRC.