Enhanced photocatalytic properties of CdS -decorated BiPO4 heterogeneous semiconductor catalyst under UV-light irradiation

Abstract CdS@BiPO 4 nanocomposite photocatalysts, composed of monoclinic BiPO 4 nanorods with an average diameter of 150 nm and length of 1.0 μm and hexagonal CdS nanocrystals with an average diameter of 8.0 nm, were synthesized by an in-situ heterogeneous nucleation and growth in the solutions at room temperature. Their phase components, microstructures and surface morphologies were characterized by XRD, FESEM, HRTEM and XPS and, in particular, the catalytic performance of CdS@BiPO 4 composites with different CdS/BiPO 4 weight ratios were studied through the degradation of methyl orange (MO) solution under UV-light irradiation. It has been found that the CdS nanocrystals are uniformly attached on the surface of BiPO 4 nanorods and no impurity phases are detected by XRD in the CdS@BiPO 4 composite catalysts, while their photocatalytic performances are notably enhanced compared with their individual constituent phases. Moreover, the composite catalyst with 6 wt% of CdS has been shown to possess the highest photocatalytic activity, which promotes MO to degrade to 95.4% in 45 min under UV light irradiation, about 1.40 and 7.50 times higher than that of single phases BiPO 4 and CdS, respectively. The formation of BiPO 4 /CdS heterojunctions apt to reduce recombination of the photogenerated carriers in CdS@BiPO 4 due to the favorable built-in electric fields at their interfacial area is believed responsible for the improved photocatalytic performances. On the basis of the experimental results and discussions, a possible charge transfer mechanism for the enhanced photocatalytic activity under UV light irradiation was also proposed.