Hollow CeO2 dodecahedrons: one-step template synthesis and enhanced catalytic performance

Abstract

Novel hollow CeO₂ dodecahedrons were synthesized using ZIF-67 nanocrystals as templates via a one-step liquid phase reaction for the first time. The structure, composition, morphology, surface chemical states, and band gap of the as-prepared hollow CeO₂ dodecahedrons were thoroughly investigated with XRD, SEM, TEM, HR-TEM, XPS, Raman, UV-Vis and ICP-AES. The hollow structures, with a specific BET surface area as high as 128 m² g⁻¹, are composed of small CeO₂ nanocrystallites less than 5 nm. The formation mechanism of hollow CeO₂ dodecahedrons was proposed, and the relative rate between Ce³⁺ hydrolysis and template dissolution was found to be the key to the successful formation of well-defined hollow dodecahedrons. The CO oxidation catalytic activities of hollow CeO₂ dodecahedrons revealed an excellent performance with a complete CO conversion at 170 °C and a superior catalytic stability, which was attributed to the synergistic effect of large surface area, small crystallites, hollow structure, large amount of oxygen vacancies, and the containing Co species. This work provides a rapid and cost-efficient approach to synthesize a new dodecahedral CeO₂ hollow structure, which broadens the way to synthesize crystalline metal oxide with controllable morphologies in mild solution conditions.