Enhanced Durability of Automotive Fuel Cells via Selectivity Implementation by Hydrogen Spillover on the Electrocatalyst Surface

Abstract

Startup and shutdown (SU/SD) events in automotive polymer electrolyte membrane fuel cells cause an unintended oxygen reduction reaction (ORR) due to the mixing of air in the anode, leading to instantaneous potential jumps and subsequent carbon corrosion in the cathode. Here, a selective electrocatalysis method for the hydrogen oxidation reaction (HOR) is presented as a promising approach for inhibiting the ORR and preventing cathodic corrosion during SU/SD events. Platinum (Pt) supported on titanium dioxide (TiO2) demonstrated HOR-selective electrocatalysis, made possible by extreme variation in conductivity according to the hydrogen concentration in the atmosphere. Under hydrogen-rich conditions, hydrogen spillover occurred and led to the formation of a conduction pathway on the Pt/TiO2 surface, promoting the HOR. Under oxygen-rich conditions, the conductivity of the TiO2 surface caused it to return to its original insulating nature, inhibiting the ORR. In an SU/SD simulation protocol test, the HOR-selective Pt/TiO2 demonstrated three-times-higher durability in a membrane electrode assembly in comparison with a commercial Pt/C catalyst.