Facile synthesis of Fe3O4@pyrogallol-formaldehyde resin@Ag core–shell nanomaterials for the catalytic degradation of contaminants

Abstract

Noble metal nanoparticles (NPs) show excellent performance in catalysis, but their strong aggregation effect can lead to a decrease in or even disappearance of their catalytic activity. In this study, Fe₃O₄@pyrogallol-formaldehyde resin@Ag (Fe₃O₄@PGFR@Ag) nanomaterials were synthesized using Fe₃O₄ as a magnetic core and pyrogallol-formaldehyde resin (PGFR) as a shell layer. The presence of Fe₃O₄ ensured rapid material recovery. At the same time, the phenolic hydroxyl group in PGFR enabled the in situ reduction of Ag⁺ to form embedded Ag NPs, effectively avoiding the aggregation and shedding of Ag NPs. Cetyltrimethylammonium bromide (CTAB) was used to modify the surface charge of the catalyst. Results showed that negatively charged Fe₃O₄@PGFR@Ag exhibited high catalytic activity, with a 90% higher catalytic rate constant for cationic dye rhodamine B (RhB) compared with Fe₃O₄@PGFR@Ag-CTAB. Positively charged Fe₃O₄@PGFR@Ag-CTAB showed high catalytic activity, with a 124% higher catalytic rate constant for the anionic dye methyl orange (MO) compared with Fe₃O₄@PGFR@Ag. Therefore, the matching of the charges of the catalyst and contaminants, which facilitates the adsorption of the pollutants around the catalyst, has a significant impact on the catalytic performance and should be considered in the process of pollutant treatment.