In Situ Bond Modulation of Graphitic Carbon Nitride to Construct p–n Homojunctions for Enhanced Photocatalytic Hydrogen Production. (5th August 2016)

• Record Type: Journal Article
• Authors: Liu, Guigao; Zhao, Guixia; Zhou, Wei; Liu, Yanyu; Pang, Hong; Zhang, Huabin; Hao, Dong; Meng, Xianguang; Li, Peng; Kako, Tetsuya; Ye, Jinhua
• Is Part Of: Advanced functional materials. Volume 26:Number 37(2016)
• Page Start: 6822
• Page End: 6829
• Publication Date: 2016-08-05
• Subjects: bond modulation -- graphitic carbon nitride -- photocatalysis -- p–n homojunctions -- solar energy conversion; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201602779
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract : Graphitic carbon nitride (g‐C3 N4 ) has recently emerged as an attractive photocatalyst for solar energy conversion. However, the photocatalytic activities of g‐C3 N4 remain moderate because of the insufficient solar‐light absorption and the fast electron–hole recombination. Here, defect‐modified g‐C3 N4 (DCN) photocatalysts, which are easily prepared under mild conditions and show much extended light absorption with band gaps decreased from 2.75 to 2.00 eV, are reported. More importantly, cyano terminal CN groups, acting as electron acceptors, are introduced into the DCN sheet edge, which endows the DCN with both n‐ and p‐type conductivities, consequently giving rise to the generation of p–n homojunctions. This homojunction structure is demonstrated to be highly efficient in charge transfer and separation, and results in a fivefold enhanced photocatalytic H2 evolution activity. The findings deepen the understanding on the defect‐related issues of g‐C3 N4 ‐based materials. Additionally, the ability to build homojunction structures by the defect‐induced self‐functionalization presents a promising strategy to realize precise band engineering of g‐C3 N4 and related polymer semiconductors for more efficient solar energy conversion applications. Abstract : The p–n homojunction graphitic carbon nitride (g‐C3 N4 ) photocatalysts with extended light absorption are prepared via in situ bond modulation, which is achieved by low‐temperature heating g‐C3 N4 with NaBH4 . Such a p–n homojunction endows g‐C3 N4 with much increased π‐electron delocalization and highly improved carrier separation and transfer. Consequently, the materials exhibit a fivefold enhanced photocatalytic hydrogen evolution activity under visible light irradiation.