Bi-quantum dots co-sensitized TiO2 nanocomposites: Templated synthesis and stabilized by polymer brushes

In this paper, a new strategy is reported to produce CdS–CdSe nanoparticles co-sensitized TiO2 nanocomposites via polymer brush template. The anonic functional polymer (polymethacrylate cadmium) are grafted on TiO2 surface via the surface–initiated atomic transfer radical polymerization using biomimetic anchor. The coordinated cadmium as the source precursor reacts with H2S to generate CdS nanocrystals on TiO2 surface. Interestingly, after reaction, the polymer brush can acts as the nanoreactor for generating and shaping CdSe nanoparticles via the absorption of cadmium ions by carboxylate groups and subsequent reaction with Na2SeSO3, the high density CdS or CdS–CdSe nanocrystals can be multiply uploaded on TiO2 surface by repeated steps. CdS nanoparticles have very small size of about 3–5 nm and the size of CdS–CdSe bi-nanocrystals is about 5–10 nm, which are stabilized by tether polymer brush. The light absorption of CdS/TiO2 and CdS–CdSe/TiO2 are investigated and both are expanded to visible light region.