The facet-dependent catalytic performance of CeO2 nanocatalysts in the decomposition of ammonium perchlorate

Abstract

CeO2 nanocrystals can be used as an excellent catalyst in ammonium perchlorate (AP) decomposition, and exploring their catalytic performance on specific crystal facets is crucial for a deeper understanding of the reaction mechanism. Herein, CeO2 nanorods (CeO2-R) with (110) facets, octahedra (CeO2-O) with (111) facets and cubes (CeO2-C) with (100) facets were successfully synthesized, and their activity in AP decomposition showed an order of CeO2-R>CeO2-C>CeO2-O. Specifically, the THTD decreased from 428.6 ℃ to 357.8 ℃, 385.4 ℃ and 410.6 ℃ for (110), (100) and (111) facet, respectively. The XPS and EPR results confirmed a direct positive correlation between the oxygen vacancies concentration on the facets and their catalytic performance, and through detailed tracking experiments with TG-MS, the following reasonable conclusion can be drawn: oxygen vacancies can not only facilitate the adsorption of NH3 which is the main decomposition product, but also reduce the band gap of CeO2, and then promotes the deep dissociation of NH3. This work presented a clear facet-dependent activity of CeO2 in the thermal decomposition of AP and comprehensively proved the supportive role of oxygen vacancies on different facets in the reaction.