Boosting photoassisted activity for catalytic oxidation of benzoic acid and reduction of 4-nitrophenol with Ag-supported Fe₃O₄ aerogel

In this study, a Fe₃O₄-based aerogel was successfully prepared using a sol-gel method followed by supercritical freezing; upon Ag loading, the prepared material exhibited high visible light-assisted Fenton-oxidation and reduction activities for benzoic acid removal and 4-aminophenol production, respectively. The photocatalytic-assisted reaction mechanisms of the Ag-loaded Fe₃O₄-based aerogel were investigated. The proposed mechanisms showed that photogenerated holes and electrons play important roles in the generation of hydroxyl radicals involved in the oxidation and reduction processes, respectively. The highly efficient light-assisted oxidation and reduction could be attributed to the unique mesoporous structure of the Fe₃O₄-based aerogel and to the Ag loading, which provides a high specific surface area, abundant active sites, and increased amounts of active radicals. In addition, the ferromagnetism of the Fe₃O₄-based aerogel endows it with recyclability and reusability. Based on the high activity of the Ag-loaded Fe₃O₄-based aerogel for light-assisted oxidation and reduction, this work provides new insights into the design of an efficient aerogel catalyst for environmental remediation.