One-pot chemical vapor deposition (OP-CVD) of period-4 transition metal oxide catalysts supported on CeO2: A comparative study for CO Oxidation

Ceria-supported catalysts have been used in catalysis, however, facile synthesis routes are a necessity. Herein, we develop transition metal oxide catalysts (TMO x ) over CeO 2 support via one-pot chemical vapor deposition (OP-CVD), where period 4 TM: Fe, Co, Ni, and Cu were considered. The MO x /CeO 2 showed negligible pore structure changes and SSA. Catalysts effectively meet the target loading and dispersion of TMO x , and their adsorption on CeO 2 were indicative of the potential for high catalytic activity. The in-situ Raman measurements confirmed generation of oxygen vacancies (O v ) with inclusion of MO x by formation of structural defects. XRD results validated that all catalysts resembled crystal structure to that of ceria corroborating lower crystallites and thorough dispersion of surface species. The XPS measurements revealed the electronic structure of all elements in the catalysts for their available oxidation states. The synthesized catalysts were then applied to the CO oxidation reaction as a model reaction. Among the catalysts, CuO x /CeO 2 showed the highest catalytic activity (∼100% CO conversion at ∼178°C). H 2 -TPR analysis revealed the reducibility and redox capability of the catalysts. CuO x /CeO 2 exhibited the low-temperature reducibility and higher hydrogen consumption, indicating highly accessible and mobile oxygen species beneficial for CO oxidation. Overall findings demonstrate that catalytic performance is governed not only by the concentration of oxygen vacancies (O v ) but also by the intrinsic reactivity of the interfacial metal sites and their ability to facilitate oxygen transfer with CeO 2 support. Additionally, OP-CVD served as an effective method for synthesizing supported catalysts for diverse catalytic applications.