Acta Phys. -Chim. Sin. ›› 2024, Vol. 40 ›› Issue (12): 2408002.doi: 10.3866/PKU.WHXB202408002

Special Issue: Solar fuel preparation

• ARTICLE • Previous Articles     Next Articles

In Situ Assembled ZnWO4/g-C3N4 S-Scheme Heterojunction with Nitrogen Defect for CO2 Photoreduction

Jianyu Qin, Yuejiao An, Yanfeng Zhang*()   

  1. National Demonstration Center for Experimental Chemistry Education, Hebei Key Laboratory of Inorganic Nano-materials, College of Chemistry and Materials Science, Hebei Normal University, Shijiazhuang 050024, China
  • Received:2024-08-01 Revised:2024-09-02 Accepted:2024-09-02 Published:2024-11-09
  • Contact: Email: zhangyanfeng@hebtu.edu.cn (Yanfeng Zhang)
  • Supported by:
    ebei Provincial Natural Science Foundation(B2020205013); ebei Provincial Natural Science Foundation(B2022205008); Science and Technology Project of Hebei Normal University of China(L2021K01); Innovation Capability Improvement Plan Project of Hebei Province(22567604H)

Abstract:

Reforming CO2 into storable solar fuels via semiconductor photocatalysis is considered an effective strategy to solve the greenhouse effect and resource shortage. Unfortunately, the problem of rapid photogenerated carriers severely limits the CO2 reduction capability of one-component catalysts. The fabrication of S-scheme heterojunctions with defects can result in efficient spatial separation of photo-generated charge carriers and increase adsorption and activation of nonpolar molecules. Herein, ZnWO4/g-C3N4 S-scheme heterojunctions with defects are constructed through in situ growth method. The experiments show that the generation rate of CO from CO2 reduction is up to 232.4 μmol∙g−1∙h−1 with a selectivity close to 100%, which is 11.6 and 8.5 times higher than those of pristine ZnWO4 and g-C3N4, respectively. In situ XPS and work function analyses demonstrate the S-scheme charge transport pathway, which facilitates the spatial segregation of photogenerated carriers and promotes CO2 reduction. In situ ESR illustrates that CO₂ molecules are adsorbed by nitrogen vacancies, which act as photoelectron acceptors during the photocatalytic reaction and are favorable for charge trapping and separation. The S-scheme charge transport mode and nitrogen vacancy work together to stimulate the efficient conversion of CO2 to CO. This work presents significant insights to the cooperative influence of the S-scheme charge transport mode and defects in regulating CO2 reduction activity.

Key words: S-scheme heterojunction, ZnWO4, g-C3N4, Nitrogen vacancy, CO2 photoreduction