Novel anode catalyst layer structure with gradient pore size distribution for highly efficient proton exchange membrane water electrolyzers

Abstract

The structure design of the anode catalyst layer (ACL) is crucial to the performance of the proton exchange membrane water electrolyzer (PEMWE). In this work, a novel ACL structure is designed using the pore-forming agents (PF) in catalyst ink. The performance of PEMWE is systematically investigated by controlling the pore in inner layer and outer layer of ACL by adding PF. Scanning electron microscope (SEM) shows that the surface pores of the ACL are significantly regulated using PF. At the current density of 3 A cm⁻², the cell voltage of the optimized gradient ACL is 2.063 V, 154 mV lower than the 2.217 V in single-layer ACL. An electrolysis efficiency of PEMWE of 86.10 %@1 A cm⁻² is achieved. Electrochemical impedance spectroscopy (EIS) results shows that the ohmic resistance of the optimized gradient ACL is 141.31 mΩ cm², which is 18.23 % lower than that of the single-layer ACL. Furthermore, the distribution function of relaxation times exhibits a significant decrease in mass transfer impedance. These results confirms that the ACL structure with gradient pore size distribution greatly improves mass transfer in PEMWE. Therefore, the ACL structural design strategy is efficient to the widespread adoption of PEMWE for clean hydrogen production.