Suppressing Hydrogen Crossover and Scavenging Radicals By Incorporation of Pt and Cerium-Zirconium Oxide for Polymer Electrolyte Water Electrolyzers

Abstract

Polymer electrolyte water electrolysis (PEWE) is one of the key technologies for green hydrogen production. It has the advantages of operating at relatively high current densities and differential pressures. The hydrogen gas produced, under high cathodic pressure and with a thin membrane, tends to cross over to the anode chamber, forming explosive H2/O2 gas mixture and posing severe safety concerns for the device. Literature has shown that one effective solution is the use of Pt as the recombination catalyst. On the other hand, radical attacks to the PFSA-based membrane leads to possible thinning and pinhole formation, which deteriorates the electrochemical performance and eventually causes cell failure. To this end, ceria is often employed as a radical scavenger. In this work, we report the co-incorporation of Pt and cerium-zirconium oxide in solution-cast Nafion membranes for the dual functions of suppressing hydrogen crossover and scavenging of radicals. We show that the hydrogen in oxygen content in the anode gas stream is significantly reduced with the incorporation of Pt, and the inclusion of cerium-zirconium oxide inside the membrane is able to decrease fluoride release rate in a 100-hour constant-current water electrolysis measurement. This study provides guidance in developing proton exchange membranes with enhanced durability and safe operating range.