High performance platinum nanorod assemblies based double-layered cathode for passive direct methanol fuel cells

• A double-layered cathode based on Pt nanorod assemblies was fabricated.
• Pt nanorods formed a network on top of the commercial Pt/C layer.
• An ESA increase of ∼50% was observed for the double-layered cathode.
• Significant reduction of Pt loading up to 50% was achieved for the DMFCs.

Reduction of the precious metal catalyst loading, especially in the cathode, is critical for the development of passive direct methanol fuel cells (DMFCs). Herein, a Pt nanorod assemblies based double-layered cathode is reported with significant catalyst loading reduction up to 50%. The nanorods, consisting of linear aggregates of Pt nanoparticles, are prepared from platinum carbonyl complexes and assembled on top of a Pt/C catalyst layer for the double-layered cathode fabrication. The maximum power density of a passive DMFC with the double-layered cathode, using 2.0 M methanol and at a temperature of 25 °C, is ca. 39.4 mW cm−2 at a Pt loading of 2.0 mg cm−2; and it is ca. 29.1 mW cm−2 at a Pt loading of 1.0 mg cm−2 comparable to that with only a conventional Pt/C layer at a Pt loading of 2.0 mg cm−2. The improved cell performance is ascribed to increased catalyst utilization and decreased charge-transfer resistance in the double-layered cathode as confirmed by electrochemical characterization and equivalent circuit analysis. The Pt nanorod assemblies based systems hold great potential for the cost reduction of DMFCs.