A mixture design approach to optimizing the cathodic compositions of proton exchange membrane fuel cell

Abstract

Cathodic catalyst layers for proton exchange membrane fuel cells (PEMFCs) are prepared according to a spraying technique, and the optimal composition of the catalyst layer is investigated by applying a mixture design approach, where the power density of the PEMFC is used as the response of the model. Based on the conventional experimental design, the optimal Nafion content of the electrocatalytic layers of a PEMFC is 35%, and a maximum power density ( P max) of 239.5 mW cm −2 is attained. Polytetrafluoroethylene (PTFE) is added to the cathodic catalyst layer to manage water, and the relationship between the P max of the PEMFC ( y) and the cathodic pseudo-compositions ( Y 1 (Pt/C), Y 2 (Nafion) and Y 3 (PTFE)) is obtained: y = 204.40 Y 1 + 198.60 Y 2 + 188.44 Y 3 + 167.46 Y 1 Y 2 ( R 2 = 0.9908 ) Based on the constant power density contours of the cathodic compositions, the optimal weight fractions of Pt/C, Nafion and PTFE are 0.68, 0.29 and 0.03, respectively, and the corresponding P max is 266.5 mW cm −2.