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

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, FeO@pyrogallol-formaldehyde resin@Ag (FeO@PGFR@Ag) nanomaterials were synthesized using FeO as a magnetic core and pyrogallol-formaldehyde resin (PGFR) as a shell layer. The presence of FeO ensured rapid material recovery. At the same time, the phenolic hydroxyl group in PGFR enabled the 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 FeO@PGFR@Ag exhibited high catalytic activity, with a 90% higher catalytic rate constant for cationic dye rhodamine B (RhB) compared with FeO@PGFR@Ag-CTAB. Positively charged FeO@PGFR@Ag-CTAB showed high catalytic activity, with a 124% higher catalytic rate constant for the anionic dye methyl orange (MO) compared with FeO@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.