Surface state modulation for size-controllable photodeposition of noble metal nanoparticles on semiconductors†
Precise control of the size and distribution of noble metal nanoparticles exerts obvious effects on the performance of heterogeneous catalysts and has received tremendous interest. The photochemical deposition method has advantages in adjusting chemical states, morphology, etc., but the tuning of size and distribution remains a big challenge. In this work, via modulating the surface states and surface charges of the TiO2 support, the size and distribution of noble metals including Ag, Pt, Au and Pd were precisely controlled. We demonstrated that photoelectrons located in the conduction band tend to form larger noble metal nanoparticles, while surface state confined electrons could form smaller nanoparticles. The thus-prepared noble metals/TiO2 catalysts exhibit good potential in both photocatalytic H2 evolution and catalytic oxidation of HCHO. This work not only provides a green and effective method to control the particle size of noble metals on metal oxides, but also is helpful in understanding the role of surface states in photocatalytic processes.