The improved photocatalytic performance of the gully-like CdS-APS@TiO2-ZrO2 composite by constructing Z-scheme heterojunction

Using monodisperse polystyrene (PS) microspheres as the template, a series of CdS-APS@TiO 2 -ZrO 2 composites (APS = 3-aminopropyltriethoxysilane) with gully-like morphology were prepared. Results from various characterisation methods indicated that grafting CdS did not change the original gully-like structure of the TiO 2 -ZrO 2 composite. However, this unique gully-like structure could provide more channels for the transfer of electrons and inhibit the recombination of photogenerated carriers. Compared with pure TiO 2 and ZrO 2 , the CdS-APS@TiO 2 -ZrO 2 composite had a red-shifted band edge absorption due to the improvement of its physical and chemical properties. The results of photoluminescence spectroscopy and the electrochemical impedance showed that the lifetime of photogenerated charge carriers in the CdS-APS@TiO 2 -ZrO 2 composite was prolonged, which inhibited the recombination of photogenerated electron–hole pairs. The results of multi-mode photocatalytic experiments revealed that CdS-APS@TiO 2 -ZrO 2 composite exhibited the best photocatalytic activity. Moreover, the hydrogen evolution amount was 90 times P25, which has good cycling stability. Finally, a direct dual Z-scheme photocatalytic mechanism was proposed by investigating the active species in the photocatalytic reaction of the CdS-APS@TiO 2 -ZrO 2 composite. The excellent microscopic morphology of CdS-APS@TiO 2 -ZrO 2 composite is beneficial to improve the separation efficiency of electrons and holes. Meanwhile, the formation of heterojunction provides more ways for electron transfer. • CdS-APS@TiO 2 -ZrO 2 composite was prepared by PS microspheres as the template. • Grafting CdS did not change the microscopic morphology of the composite. • The composite grafted with CdS has a good light absorption range. • Gully-like structure provides more channels for transfer of electrons and holes. • A rate of hydrogen evolution of CdS-APS@TiO 2 -ZrO 2 composite is 90 times of P25.