Effect of calcination on the photocatalytic performance of CdS under visible light irradiation

The photocatalytic activity of cadmium sulfide (CdS) under visible light irradiation was evaluated by degrading methylene blue (MB). Upon calcination in air/O2 atmosphere, the photocatalytic activity of CdS was enhanced by eliminating the trap energy levels. Meanwhile, the effect of cadmium oxide (CdO) on the photocatalytic activity of CdS was also studied by in situ forming CdO on the surface of CdS. CdO blocked the light absorption of CdS, which decreased the photocatalytic activity of CdS.

Research highlights▶ Hexagonal CdS was directly treated by a simple calcination method in air/O2 atmosphere to eliminate the trap energy levels which are the recombination centers for the photogenerated electrons and holes. ▶ The photocatalytic activities for degrading methylene blue by CdS calcined in air and O2 atmosphere were enhanced by 87.5% and 69.7%, respectively. ▶ At the same time, the effect of CdO on the photocatalytic activity of CdS was also studied by in situ forming CdO on the surface of CdS. The formed CdO decreased the photodegradation efficiency of CdS through blocking the light absorption of CdS.