Agn+ quantum dots obtained via in situ photodeposition method as photocatalytic CO2 reduction cocatalyst: Borrowing redox conversion between Ag+ and Ag0

Abstract Ag n + -loaded TiO 2 (Ag n + /TiO 2 ) nanocomposites were prepared by an in situ photodeposition method. There is no sacrificial agent during the loading procedure, and the photo-reduction process is always accompanied by a photo-oxidation process, resulting in the simultaneous presence of Ag 0 and Ag + . Surprisingly, the obtained Ag n + clusters can be considered as quantum dots with an average size of 2.75 nm, and this quantum size for noble metal is very difficult to get by conventional photodeposition method. Furthermore, we can adjust the ratio of Ag 0 and Ag + to achieve dynamic balance by changing the processing temperature (60 °C - yellow to 180 °C - violet black). The results indicate that the ratio of Ag 0 and Ag + is a key factor for the photocatalytic efficiency.