Synthesis of Copolymerized Carbon Nitride Nanosheets from Urea and 2-Aminobenzonitrile for Enhanced Visible Light CO2 Reduction with a Ruthenium(II) Complex Catalyst

Kengo Shibata, Kosaku Kato, Constantine Tsounis, Tomoki Kanazawa, Daling Lu, Shunsuke Nozawa, Akira Yamakata, Osamu Ishitani, Kazuhiko Maeda

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Copolymerized carbon nitride nanosheets (NS-C3N4) are synthesized by heating a mixture of urea and 2-aminobenzonitrile (ABN) at 823 K for 2 h in air. The visible light-absorption capability of the copolymerized NS-C3N4 can be improved with an increase in the ABN content in the starting material, while maintaining the rather negative conduction band potential of NS-C3N4. With the aid of a ruthenium(II) complex catalyst, the copolymerized NS-C3N4 becomes active for CO2 reduction into formate (>90% selectivity) under visible light (λ > 400 nm) in the presence of triethanolamine as an electron donor. The activity is enhanced with increasing the starting ABN content to reach a maximum at a certain amount, beyond which it declines. The optimized material, modified with a silver promoter and a phosphonate-functionalized ruthenium(II) catalyst, gives a high turnover number of 6000 (vs Ru catalyst) for formate production. Physicochemical analyses indicate that increasing the starting ABN concentration improves the visible light-absorption capability of the copolymerized NS-C3N4, but increases the number of trap states, which can work as recombination centers of photogenerated electrons and holes. Therefore, an appropriate adjustment of the ABN comonomer amount is essential to obtain copolymerized NS-C3N4, which shows high photocatalytic activity.

Original languageEnglish
Article number1900461
JournalSolar RRL
Volume4
Issue number8
DOIs
Publication statusPublished - Aug 1 2020
Externally publishedYes

Keywords

  • artificial photosynthesis
  • formates
  • hybrid materials
  • photocatalysis
  • solar fuels

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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