A hierarchical cathode catalyst layer architecture for improving the performance of direct methanol fuel cell

•A novel MEA with hierarchical cathode catalyst layer (CL) is proposed.•The MEA shows outstanding DMFC performance despite low Pt loading (1.0 mg cm−2).•The MEA can maintain the high ORR activity of cathode despite the methanol crossover.

We report the fabrication of a hierarchical cathode catalyst layer (CL) for application in direct methanol fuel cells (DMFCs). The hierarchical CL, comprised of Pt black as the inner layer and Pt/C as the outer layer, has appropriate structural properties for DMFC cathode. The inner CL with compact structure decreases the CL thickness and prevent Pt sites from methanol contamination, and the cathode outer CL with porous structure increase the electrochemical active surface area. Consequently, the hierarchical cathode CL is able to offset the adverse effect of methanol crossover on the cathode performance by enhancing the Pt catalyst utilization for oxygen reduction reactions (ORR). Therefore, the newly developed membrane electrode assembly (MEA) can maintain the high ORR activity of the cathode catalysts despite the methanol crossover. At a high methanol concentration (3 M), it shows high maximum power density (0.156 W cm−2) despite only 1.0 mg cm−2 of Pt in the cathode CL.

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