Intensified Catalytic Decomposition of Acetone at Room Temperature Using a Ag-Modified CeO₂–Al₂O₃ Binary Metal Oxide Support: Enhancing Synergies, Role of Relative Humidity, and In Situ Mechanistic Interpretation

This study probes the effectiveness of using a Ag/CeO2–Al2O3 mixed metal oxide support compared to Ag-modified single supports (Ag/CeO2 and Ag/Al2O3) on acetone removal under VUV irradiation at room temperature. It is shown that under VUV light, the type of support can affect acetone oxidation at the microscopic and macroscopic levels. At the microscopic level, the findings from X-ray photoemission spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) analyses showed that the nature of the support can influence the oxidation state of silver. At the macroscopic level, it was demonstrated that the support can control the dominance of the oxidation mechanism. While Ag/Al2O3, compared to Ag/CeO2, can boost acetone and ozone conversion, the selectivity of Ag/Al2O3 (88%) was lower than that of Ag/CeO2 (96%). However, not only can Ag/CeO2–Al2O3 with an optimized 1:1 ratio of CeO2/Al2O3 oxidize 96 and 98% of the inlet acetone and ozone, respectively, but also the reaction selectivity was above 97%. Moreover, the influence of relative humidity (RH) on Ag/CeO2–Al2O3 activity under VUV light was investigated, and it proved the dual character of RH. Although RH improved the VUV photolysis performance in the gaseous state, it poisoned the gas–catalyst interface, leading to an inhibition role in the catalytic reactions. The high and sustainable performance of the Ag/CeO2–Al2O3 catalyst at room temperature, achieved through engineering of the mixed metal oxide support and maintained even under humid conditions, offers a promising solution for indoor air quality control in diverse settings. These include residential, commercial, and industrial spaces and potential applications in reducing volatile organic compounds (VOCs) from automotive emissions.