Electrochemical phenyl oxidation: A limiting factor of oxygen evolution reaction in water electrolysis

This mini review explains the electrochemical phenyl oxidation of ionomers in the anode catalyst layers of the water electro-lyzer that significantly impacts the performance and durability of the device. Although the relevant studies on phenyl oxidation on platinum group metal-free catalysts under high electrode potential are scarce, several studies with platinum group metal catalysts indicated that the impact of electrochemical phenyl oxidation can be profound. In the first part, this review sum-marizes ionomer-catalyst interactions that impact alkaline electrochemical devices, emphasizing the importance of minimizing interactions between the phenyl moiety of ionomers and oxygen evolution reaction catalysts. In the second part, we discuss the adsorption energies of phenyl groups found in ionomer fragments on different oxygen evolution catalysts. The mitigation strategies of electrochemical phenyl oxidation for advanced water electrolyzers are briefly discussed at the end of the review.

Automated summary

This mini review explains the significant impact of electrochemical phenyl oxidation on the performance and durability of water electrolyzers in the anode catalyst layers. Although studies on phenyl oxidation on platinum group metal-free catalysts under high electrode potential are limited, studies with platinum group metal catalysts have shown profound effects. The review summarizes ionomer-catalyst interactions in alkaline electrochemical devices, emphasizes the importance of minimizing interactions between the phenyl moiety of ionomers and oxygen evolution reaction catalysts, and discusses the adsorption energies of phenyl groups on different oxygen evolution catalysts. Mitigation strategies for electrochemical phenyl oxidation in advanced water electrolyzers are briefly discussed.