Highly enhanced visible-light photocatalytic NOx purification and conversion pathway on self-structurally modified g-C-3N4 nanosheets  

作　　者：Yuhan Li Yanjuan Sun Wingkei Ho Yuxin Zhang Hongwei Huang Qiang Cai Fan Dong 

机构地区：[1]Chongqing Key Laboratory of Catalysis and New Environmental Materials,Engineering Research Center for Waste Oil Recovery Technology and Equipment, Ministry of Education, College of Environment and Resources, Chongqing Technology and Business University, Chongqing 400067. China [2]Department of Science and Environmental Studies. The Center for Education in Environmental Sustainability, The Education University of Hong Kong. Hong Kong, China [3]College of Materials Science and Engineering, National Key Laboratory of Fundamental Science of Micro/Nano-Devices and System Technology. Chongqing University.Chongqing 400044. China [4]School of Materials Science and Technology, National Laboratory of Mineral Materials, China University of Geosciences, Beijing 100083, China

出　　处：《Science Bulletin》2018年第10期609-620,共12页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China(51478070,21501016 and 21777011);the National Key R&D Program of China(2016YFC0204702);the Innovative Research Team of Chongqing(CXTDG201602014);the Natural Science Foundation of Chongqing(cstc2016jcyj A0481,cstc2017jcyj BX0052);the Early Career Scheme(ECS 809813) from Hong Kong;the Internal Research Grant from Hong Kong Institute of Education(R3588)

摘　　要：The unmodified graphitic carbon nitride(g-C_3N_4) suffers from low photocatalytic activity because of the unfavourable structure.In the present work,we reported a simple self-structural modification strategy to optimize the microstructure of g-C_3N_4 and obtained graphene-like g-C_3N_4 nanosheets with porous structure.In contrast to traditional thermal pyrolysis preparation of g-C_3N_4,the present thermal condensation was improved via pyrolysis of thiourea in an alumina crucible without a cover,followed by secondary heat treatment.The popcorn-like formation and layer-by-layer thermal exfoliation of graphene-like porous g-C_3N_4 was proposed to explain the formation mechanism.The photocatalytic removal performance of both NO and NO_2 with the graphene-like porous g-C_3N_4 for was significantly enhanced by selfstructural modification.Trapping experiments and in-situ diffuse reflectance infrared fourier transform spectroscopy(DRIFTS) measurement were conducted to detect the active species during photocatalysis and the conversion pathway of g-C_3N_4 photocatalysis for NO_x purification was revealed.The photocatalytic activity of graphene-like porous g-C_3N_4 was highly enhanced due to the improved charge separation and increased oxidation capacity of the ·O_2^- radicals and holes.This work could not only provide a novel self-structural modification for design of highly efficient photocatalysts,but also offer new insights into the mechanistic understanding of g-C_3N_4 photocatalysis.The unmodified graphitic carbon nitride（g-C3N4） suffers from low photocatalytic activity because of the unfavourable structure.In the present work,we reported a simple self-structural modification strategy to optimize the microstructure of g-C3N4 and obtained graphene-like g-C3N4 nanosheets with porous structure.In contrast to traditional thermal pyrolysis preparation of g-C3N4,the present thermal condensation was improved via pyrolysis of thiourea in an alumina crucible without a cover,followed by secondary heat treatment.The popcorn-like formation and layer-by-layer thermal exfoliation of graphene-like porous g-C3N4 was proposed to explain the formation mechanism.The photocatalytic removal performance of both NO and NO2 with the graphene-like porous g-C3N4 for was significantly enhanced by selfstructural modification.Trapping experiments and in-situ diffuse reflectance infrared fourier transform spectroscopy（DRIFTS） measurement were conducted to detect the active species during photocatalysis and the conversion pathway of g-C3N4 photocatalysis for NOx purification was revealed.The photocatalytic activity of graphene-like porous g-C3N4 was highly enhanced due to the improved charge separation and increased oxidation capacity of the ·O2- radicals and holes.This work could not only provide a novel self-structural modification for design of highly efficient photocatalysts,but also offer new insights into the mechanistic understanding of g-C3N4 photocatalysis.

关 键 词：Self-structural modification g-C3N4 Visible light photocatalysis In-situ DRIFTS Conversion pathway 

分 类 号：O643.36[理学—物理化学] O644.1[理学—化学] TB383.1[一般工业技术—材料科学与工程]