Catalytic oxidation of volatile organic compound over cerium modified cobalt-based mixed oxide catalysts synthesized by electrodeposition method

Abstract

Cerium (Ce) modified cobalt (Co)-based (Co-Ce) mixed oxide catalysts were electrodeposited on nickel foam (NF) with different Co/Ce molar ratios and directly used for the catalytic oxidation of toluene. Physicochemical properties of the obtained Co-Ce/NF catalysts were obtained by SEM, XRD, TEM, H2-TPR, O2-TPD and XPS techniques. It was found that the Co-Ce mixed oxide with a well nanosheet structure could be uniformly deposited on NF by adjusting the Co/Ce molar ratio in the initial solution for electrodeposition. H2-TPR analysis indicated that Ce doping improved the reducibility of Co-Ce/NF catalyst due to the synergistic effect between Co and Ce. In the toluene catalytic oxidation, the 10Co-Ce/NF catalyst prepared with a molar ratio of Co/Ce at 10 in the initial solution achieved the best catalytic performance among all the catalysts with a complete toluene conversion temperature of 268 °C and CO2 selectivity of 100 %. This can be contributed to the superior physiochemical properties of uniform nanosheet structure, rich surface and lattice active oxygen species at low temperatures, high content of Co3+ active species with high oxygen vacancies and Ce4+/Ce3+ redox couples in the catalyst. In addition, the 10Co-Ce/NF catalyst exhibited long-term stability in the presence of water vapor. It is expected that such a time-saving electrodeposition method could provide a promising way to prepare highly active and stable transition metal based catalysts for the oxidation of VOCs.