Suppression of H₂O₂ Formation and Durability of Various Hydrogen Anode Catalysts for Long-Life Fuel Cells

Polymer electrolyte membranes (PEMs) in fuel cells are chemically decomposed by the attack of radicals generated from H 2 O 2 , which is produced by the reaction of hydrogen adsorbed (H ad ) on the Pt anode supported on carbon black (Pt/CB) with O 2 crossing over through the PEM. We have examined various anode catalysts of PtCo/C HT (PtCo supported on acetylene-black, followed by a heat treatment), Pt/Ti 4 O 7 -C (Pt supported on Ti 4 O 7 plus amorphous carbon), and commercial Pt/CB (c-Pt/CB) with addition of WO 3 nanoparticles or IrO 2 nanosheets with respect to the H 2 O 2 formation rate j (H 2 O 2 ), activity for the hydrogen oxidation reaction (HOR), and durability in an accelerated stress test (AST) consisting of potential changes between 0.02 and 1.0 V in a half-cell with 0.1 M HClO 4 at 80 °C. These catalysts exhibited an excellent suppression of j (H 2 O 2 ) with mass activities ( MA ) for the HOR comparable to that of c-Pt/CB. The mechanism for suppression of H 2 O 2 formation was analyzed by the density functional theory calculation, which demonstrated weakened adsorption of H ad on Pt surface by an electronic modification effect or an interaction between Pt and oxides. It was found that the PtCo/C HT catalyst maintained the lowest j (H 2 O 2 ) together with high MA for the HOR over 6000 cycles.