scholarly journals Rendering Visible-Light Photocatalytic Activity to Undoped ZnO via Intrinsic Defects Engineering

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1163
Author(s):  
Lan-li Chen ◽  
Bao-gai Zhai ◽  
Yuan Ming Huang

It is significant to render visible-light photocatalytic activity to undoped ZnO nanostructures via intrinsic defect engineering. In this work, undoped ZnO nanocrystals were derived via co-precipitation synthesis. The resulting ZnO nanocrystals were characterized by means of X-ray diffraction, scanning electron microscopy, photoluminescence spectroscopy, and ultraviolet-visible absorption spectroscopy, respectively. The visible-light photocatalytic activity of the products were characterized by monitoring the decomposition of methyl orange in water under visible-light illumination of a 300 W halogen lamp. It is found that undoped ZnO nanocrystals exhibit visible-light photocatalytic activity with their first-order rate constant up to 4.6 × 10−3 min−1. Density functional calculations show that oxygen vacancies create deep energy levels at EV + 0.76 eV in the bandgap of ZnO. In conjunction with the density functional calculations, the photocatalytic degradation of methyl orange under visible-light irradiation provides direct evidence that oxygen vacancies in ZnO nanocrystals yield the visible-light photocatalytic activity. Our results demonstrate that visible-light photocatalytic activity can be endowed to undoped ZnO nanocrystals by manipulating the intrinsic defects in ZnO. Intrinsic defect-modulated ZnO photocatalysts thus represent a powerful configuration for further development toward visible-light responsive photocatalysis.

2011 ◽  
Vol 239-242 ◽  
pp. 1923-1928
Author(s):  
Qian Lin Chen ◽  
Yuan Wang ◽  
Chun Yan Zhong ◽  
Yu Guo

La3+/halogen (F-, Cl-and Br-) co-doped TiO2was synthesized by alkoxide hydrolysis method. The prepared La3+/halogen TiO2photocatalysts with anatase phases and rutile phases were characterized with XRD, EDS, TEM and surface area analytic technology. Methyl orange was used as model pollutants to evaluate its visible light photocatalytic activity. The results showed that the co-doping of La3+and halogen ions improved the surface area of TiO2. Compared with 450°C and 650°C, La3+/Cl-and La3+/Br-co-doped TiO2calcined at 550°C exhibited much higher photocatalytic activity. The optimal doping ratio of La3+/F-, La3+/Cl-and La3+/Br-was 0.4, 0.6, and 0.5 ((wt%)/(wt%)), respectively. Moreover, the degradation ratio of methyl orange on La3+/halogen co-doped TiO2with the optimal ratio were all higher than the maximum degradation ratio on La3+, F-, Cl-and Br-doped TiO2prepared by the same method.


2016 ◽  
Vol 45 (35) ◽  
pp. 13944-13950 ◽  
Author(s):  
Gang Yan ◽  
Hongfei Shi ◽  
Huaqiao Tan ◽  
Wanbin Zhu ◽  
Yonghui Wang ◽  
...  

A new 2D sheet composite Bi2OxS3−x/Nb6O17 has been prepared, which shows good visible light photocatalytic performance for the degradation of methyl orange.


2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Yan Gong ◽  
Hongtao Yu ◽  
Xie Quan

Recently a novel sliver oxide Ag3AsO4has been found to be an excellent photocatalyst with strong oxidation capability for pollutant degradation under visible light. But the origin of its high visible light photocatalytic activity was unclear which hindered further research of Ag3AsO4. For clarifying that, the electronic structure and optical properties of Ag3AsO4have been analyzed by the hybrid density functional method. The results reveal that the Ag3AsO4presents a narrow band gap with strong oxidation ability of the valence bands maximum edge and the highly delocalized charge distribution of the conduction bands minimum is beneficial for the carriers transfer to surface to participate in the photocatalytic reaction. These results provide clear explanations of the excellent visible light photocatalytic performance of the Ag3AsO4from microscopic aspect. And it is significant to design novel materials with high photocatalytic performance.


RSC Advances ◽  
2016 ◽  
Vol 6 (69) ◽  
pp. 64446-64449 ◽  
Author(s):  
Xiaosong Zhou ◽  
Bei Jin ◽  
Jin Luo ◽  
Xuyao Xu ◽  
Lingling Zhang ◽  
...  

Dramatic visible light photocatalytic activity was obtained for the degradation of methyl orange using TiO2 photocatalysts modified with polydopamine (PDA) nanospheres.


2016 ◽  
Vol 37 (2) ◽  
pp. 165-173
Author(s):  
苗慧 MIAO Hui ◽  
夏娟 XIA Juan ◽  
金凤 JIN Feng ◽  
孙林 SUN Lin ◽  
崔玉民 CUI Yu-min ◽  
...  

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