Dopant-induced surface activation of ceria nanorods for electro-oxidation of hydrogen and propane in solid oxide fuel cells

Abstract

Ceria is an excellent oxide catalyst to break H2 in the absence of noble metals and has shown great promise for potential applications in diverse technological fields. The catalytic activity of ceria is critically linked to surface composition and structure. Herein, selective doping with moderate lanthanide ions is reported to regulate surface oxygen vacancies and bonded adsorbates of ceria nanorods so as to finely tune their activities toward electro-oxidation of H2 and C3H8 in reduced-temperature solid oxide fuel cells. Lanthanide doped ceria nanorods are hydrothermally synthesized, and electrochemically evaluated as the anode catalysts for reduced-temperature SOFCs. Measurements of anode polarization resistances and fuel cell power densities show a catalytic activity in the order of Ce0.8Pr0.2O2-δ < Ce0.8Gd0.2O2-δ < Ce0.8Sm0.2O2-δ. Probing the surface structure with hydrogen temperature-programmed reduction, UV-Raman and XPS reveals that such catalytic activities are essentially determined by surface reducibility, availability of surface oxygen vacancies and strongly bonded hydroxyls.