FACILE SYNTHESIS OF ORGANIC-INORGANIC HYBRID MATERIALS AND THEIR PHOTOCATALYTIC ACTIVITY

摘要

As a typical metal free inorganic semiconductor, graphitic C_3N_4 (g-C_3N_4) has attracted intensive attention for H_2 generation, pollutant degradation and CO_2 reduction. It is well-known that the band gap of g-C_3N_4 is about 2.7 eV, which can absorb visible light up to 460 nm. Furthermore, the CB minimum (-1.12 eV vs. NHE) of g-C_3N_4 is extremely negative, so photo-generated electrons should have high reduction ability. However, the photocatalytic efficiency of the pure g-C_3N_4 is limited by the high recombination rate of its photo-generated electron-hole pairs. One of the techniques for increasing the separation efficiency of photo-generated electron-hole pairs is to form a composite photocatalyst using two kinds of semiconductors. Suitable matching of the band levels of the conduction and valence bands in the two semiconductors offers appropriate driving forces to separate and transfer photo-generated electron-hole pairs. To improve g-C_3N_4 photocatalytic activity, various semiconductor/g-C_3N_4 composite photocatalysts have been reported and used for the photodegradation of organic dyes in solution. Herein, different ratios of WO_3/g-C_3N_4 or Ag_3PO_4/g-C_3N_4 hybrid photocatalysts were synthesized. The photocatalysts were characterized by various techniques such as XRD, SEM, TEM, UV-visible DRS, and so on. The separation mechanisms of photo-excited carriers for the hybrid photocatalysts were also proposed on the basis of the results for the PL analysis.