In situ synthesis of a C-doped (BiO)2CO3 hierarchical self-assembly effectively promoting visible light photocatalysis

Abstract

Development of high-performance visible light photocatalysts is the key to environmental and energetic applications of photocatalysis technology. By combination of doping and structural optimization, semiconductors with wide band gaps could transform into highly active visible light photocatalysts. In this work, C-doped (BiO)₂CO₃ microspheres hierarchically constructed by self-assembled nanosheets were prepared via a facile hydrothermal method applying glucose as the carbon source for the first time. The incorporation of an external C element into the crystal structure of (BiO)₂CO₃ could narrow the band gap by down-shifting the conduction band, and meantime generate some localized states above the valence band edge. The C-doped (BiO)₂CO₃ hierarchical self-assembly exhibited highly enhanced and stable photocatalytic activity for NO removal under visible light illumination, far exceeding those of undoped (BiO)₂CO₃, C-doped TiO₂ and N-doped (BiO)₂CO₃. The improved photocatalytic activity could be attributed to the increased visible light absorption, improved charge separation and transfer as well as the special hierarchical structure. The C-doped (BiO)₂CO₃ microspheres also generated enhanced visible light induced photocurrent density. There exists an optical amount of C element introduced into the crystal structure. In addition, the growth mechanism of C-doped (BiO)₂CO₃ hierarchical microspheres has been proposed. By using other carbohydrates like maltose, fructose, sucrose and starch as the carbon doping source, C-doped (BiO)₂CO₃ can also be synthesized, which indicates that carbohydrates are a general type of carbon doping source. This work could provide a one-step and general method to fabricate highly active C-doped (BiO)₂CO₃ photocatalysts, which simultaneously provide new insight into the enhancement of visible photocatalysis by combination of carbon doping and structural optimization.