Boron-Doped Diamond Powder as a Durable Support for Platinum-Based Cathode Catalysts in Polymer Electrolyte Fuel Cells

Abstract

Platinum nanoparticle-supported boron-doped diamond powder (Pt/BDDP) was prepared and investigated as a durable polymer electrolyte fuel cell (PEFC) cathode catalyst. The use of the nanocapsule method enabled dense deposition of Pt nanoparticles (2–5 nm in size) on a boron-doped diamond (BDD) powder <500 nm in size. The Pt/BDDP cathode catalyst showed oxygen reduction reaction activity comparable to Pt-supported carbon black (Pt/C), indicating sufficient conductivity of the BDDP as a catalyst support. Potential cycling in a highly positive potential region (+1.0–+1.5 V vs. NHE) that simulates the start–stop operations of the PEFC was performed to investigate the durability of the Pt/BDDP catalyst. Decreases in the electrochemically active surface area of the Pt/BDDP were suppressed compared to that of Pt/C. Corrosion resistance of BDD against potential cycling was demonstrated by testing a BDD thin-film electrode. The corrosion resistance should be responsible for the improved durability of the BDDP support, possibly by lowering the Pt nanoparticle association process (e.g., agglomeration).