Ta and Nb co-doped TiO2 and its carbon-hybrid materials for supporting Pt–Pd alloy electrocatalysts for PEM fuel cell oxygen reduction reaction

Abstract

To explore possible substitutes for carbon supports in PEM fuel cell catalysts, both Ta and Nb co-doped TiO₂ (TaNbTiO₂) and carbon–TaNbTiO₂ (C–TaNbTiO₂) hybrid support materials are successfully synthesized by a modified thermal hydrolysis method. These materials are employed as support candidates for Pt–Pd alloy catalysts for the oxygen reduction reaction. Among several supported catalysts, 20 wt% Pt_0.62Pd_0.38/C_75wt%–(Ta_0.01Nb_0.03Ti_0.96O₂)_25wt% is found to have an oxygen reduction reaction (ORR) mass activity of 260 mA mg_Pt⁻¹ and an ORR loss of 30%, which are slightly better than those of the commercially available Pt/C baseline catalyst which has a mass activity of 110 mA mg_Pt⁻¹ and an ORR loss of 40% probably because of a strong physicochemical interaction among the Pt–Pd alloy catalyst particle, carbon–TaNbTiO₂ support and carbon, as well as the stability of oxide to protect carbon from corrosion by the distribution of oxide onto carbon, respectively.