Nitrogen-defect induced trap states steering electron-hole migration in graphite carbon nitride

作者：Li, Wenlu; Wei, Zhen^*; Zhu, Kaijian; Wei, Weiqin; Yang, Jun; Jing, Jianfang; Phillips, David Lee^*; Zhu, Yongfa^*

来源：Applied Catalysis B: Environmental , 2022, 306: 121142.

DOI：10.1016/j.apcatb.2022.121142

• Graphite carbon nitride
• Nitrogen defects
• Photocatalysis
• Trap states
• Femtosecond transient absorption spectroscopy

Defect structures of semiconductors intrinsically regulate the trap states, excitons and active charge carriers for artificial photosynthesis systems. A g-C3N4 system with abundant nitrogen defects was prepared through a thermal polycondensation strategy to reveal the role of trap states and exhibited a 20-fold enhanced H-2 evolution efficiency relative to bulk g-C3N4 under visible light irradiation. Subsequent femtosecond transient absorption spectroscopy study found that the N-defect induced shallow trap states can capture photogenerated electrons to inhibit deep trapping and direct recombination of photogenerated charges. The active electrons in shallow trap states can enhance the photocatalytic H-2 evolution when compared with the inactive electrons in deep trap states. Mid-infrared transient absorption spectroscopy also confirmed the increased quantity of shallow-trapped electrons without interference of other signals. This work provides new insights for steering depth of trap states and photocatalytic processes through N defects to achieve high photocatalytic performance using femtosecond transient absorption spectroscopy.

• 单位
  清华大学