Effect of the Ag+ in Ag25@ZnO nanocatalysts for the 4-nitrophenol reduction reactions

As catalysts, metal nanoclusters (NCs) have become the focus of research due to their precise structure and excellent catalytic activity. In general, it can greatly improve the catalytic activity of NCs by thermal treatment. In this work, the ZnO supported 2,4-dimethylbenzenethiol-protected-[Ag 25 (C 8 H 9 S) 18 ] - NCs (Ag 25 @ZnO) nanocatalysts were subjected to activation temperatures of 100 °C, 200 °C and 300 °C to remove the surface ligands of Ag 25  NCs and regulate the surface composition of Ag 25 @ZnO nanocatalysts. The structure of Ag 25 @ZnO nanocatalysts were characterized by XRD , SEM, TEM, EDS and XPS. In particular, the XPS results obviously confirmed that the concentration of Ag + on the catalyst surface was positively correlated with the activation temperature. Finally, the effect of the Ag  +  content on the catalytic activity of the Ag 25 @ZnO nanocatalysts was also explored. Because the content of Ag + in Ag 25 @ZnO-300 nanocatalysts is the highest, the 4-nitrophenol reduction reaction showed the best catalytic performance.