Synthesis of Copolymerized Carbon Nitride Nanosheets from Urea and 2‐Aminobenzonitrile for Enhanced Visible Light CO2 Reduction with a Ruthenium(II) Complex Catalyst. Issue 8 (19th December 2019)

• Record Type: Journal Article
• Authors: Shibata, Kengo; Kato, Kosaku; Tsounis, Constantine; Kanazawa, Tomoki; Lu, Daling; Nozawa, Shunsuke; Yamakata, Akira; Ishitani, Osamu; Maeda, Kazuhiko
• Other Names: Ong Wee-Jun guestEditor.; Maeda Kazuhiko guestEditor.
• Is Part Of: Solar RRL. Volume 4:Issue 8(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-12-19
• Subjects: artificial photosynthesis -- formates -- hybrid materials -- photocatalysis -- solar fuels; Solar energy -- Periodicals; Photovoltaic power generation -- Periodicals; Solar energy -- Research -- Periodicals; Photovoltaic power generation -- Research -- Periodicals; Periodicals; 333.7923
• DOI: 10.1002/solr.201900461
• Languages: English
• ISSNs: 2367-198X

Abstract

Abstract : Copolymerized carbon nitride nanosheets (NS‐C3 N4 ) 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‐C3 N4 can be improved with an increase in the ABN content in the starting material, while maintaining the rather negative conduction band potential of NS‐C3 N4 . With the aid of a ruthenium(II) complex catalyst, the copolymerized NS‐C3 N4 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‐C3 N4, 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‐C3 N4, which shows high photocatalytic activity. Abstract : Copolymerized carbon nitride nanosheets, synthesized from urea and 2‐aminobenzonitrile, are capable of reducing CO2 into formate with high selectivity (>90%) under visible light ( λ > 400 nm) when combined with a ruthenium(II) complex catalyst. The reinforced visible light absorption of the copolymerized material contributes to an enhanced photocatalytic activity, as compared with the urea‐derived pristine carbon nitride.