Carbon Nitride–Aromatic Diimide–Graphene Nanohybrids: Metal-Free Photocatalysts for Solar-to-Hydrogen Peroxide Energy Conversion with 0.2% Efficiency

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• 作者：Yusuke Kofuji ; Yuki Isobe ; Yasuhiro Shiraishi ; Hirokatsu Sakamoto ; Shunsuke Tanaka ; Satoshi Ichikawa ; Takayuki Hirai
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：August 10, 2016
• 年：2016
• 卷：138
• 期：31
• 页码：10019-10025
• 全文大小：552K
• 年卷期：0
• ISSN：1520-5126

文摘

Solar-to-chemical energy conversion is a challenging subject for renewable energy storage. In the past 40 years, overall water splitting into H₂ and O₂ by semiconductor photocatalysis has been studied extensively; however, they need noble metals and extreme care to avoid explosion of the mixed gases. Here we report that generating hydrogen peroxide (H₂O₂) from water and O₂ by organic semiconductor photocatalysts could provide a new basis for clean energy storage without metal and explosion risk. We found that carbon nitride–aromatic diimide–graphene nanohybrids prepared by simple hydrothermal–calcination procedure produce H₂O₂ from pure water and O₂ under visible light (λ > 420 nm). Photoexcitation of the semiconducting carbon nitride–aromatic diimide moiety transfers their conduction band electrons to graphene and enhances charge separation. The valence band holes on the semiconducting moiety oxidize water, while the electrons on the graphene moiety promote selective two-electron reduction of O₂. This metal-free system produces H₂O₂ with solar-to-chemical energy conversion efficiency 0.20%, comparable to the highest levels achieved by powdered water-splitting photocatalysts.