Preparation and Characterization of ZnTiO3/g-C3N4 Heterojunction Composite Catalyst with Highly Enhanced Photocatalytic CO2 Reduction Performance

Herein, well-crystallized ZnTiO3 particles are first prepared by hydrothermal method. A series of S-scheme heterojunction photocatalysts of ZnTiO3/g-C3N4 (referred to as ZTO/CN) with different mass ratios are synthesized by successfully doping ZnTiO3 in g-C3N4 precursors and loading ZnTiO3 onto g-C3N4 nanosheets by calcination. It is clearly found that the ZnTiO3 particles are successfully loaded on g-C3N4 nanosheets by the X-ray diffractometer, energy-dispersive X-ray spectra, and high-resolution transmission electron microscopy images. Moreover, the specific surface area of 3.0% ZTO/CN is higher than that of pure g-C3N4. Using triethanolamine as the hole sacrificial agent, the highest CO and H-2 yields are achieved in the 3.0% ZTO/CN composite catalyst under the xenon lamp irradiation for 1 h. The generation rates of CO and H-2 reach 15.19 and 5.77 & mu;mol g(-1) h(-1), respectively, which are 2.9 and 4.1 times higher than that of pure g-C3N4. The CO and H-2 yields of the ZTO/CN composite catalyst show a trend of increasing and then decreasing with the increasing of ZnTiO3 content, which is due to the fact that excess ZnTiO3 can lead to a reduction of the effective heterojunction interface between ZnTiO3 and g-C3N4, decreasing the transfer and separation efficiency of photogenerated electrons and holes and thus reducing the photocatalytic activity.