With the reduction of non-renewable energy sources, hydrogen energy and proton exchange membrane fuel cells (PEMFCs) have received significant attention due to the high efficiency and zero-emission properties. However, Pt catalysts in the cathode catalyst layer(CCL) of PEMFCs are prone to undergo dissolution-redeposition process known as Ostwald ripening under dynamic operating conditions, which results in Pt ion migration to the membrane simultaneously. The coarsening and mass loss of Pt particles reduce the oxygen reduction reaction rate and cause PEMFC performance deterioration. In this study, various CCL designs with gradient Pt particle size distributions were proposed, and their effects on mitigating Pt degradation and maintaining cell performance during long-term voltage cycling were evaluated using a one-dimensional Pt degradation model and a three-dimensional PEMFC performance model. Firstly, the accuracy of the models was validated against experimental data, with a maximum relative error of less than 10%. Then, the active reaction area, mass, and ECSA retention rate of Pt catalysts in the CCLs, as well as the performance of PEMFCs with different structures, were quantitatively compared and analyzed. The research found that compared to the control CCL consisting of only 3 nm average Pt particle size, the optimal dual-layer gradient CCL demonstrated better performance after degradation, showing a 5% higher current density at an output cell voltage of 0.45V, with the total active reaction area and mass retention rate increasing by 19.4% and 16.4%, respectively. Additionally, in multi-layer gradient CCLs, the exponential increase in Pt particle size from the MPL to the membrane was considered the ideal Pt particle distribution.
