scholarly journals Insight into the Contributions of Surface Oxygen Vacancies on the Promoted Photocatalytic Property of Nanoceria

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1168
Author(s):  
Yuanpei Lan ◽  
Xuewen Xia ◽  
Junqi Li ◽  
Xisong Mao ◽  
Chaoyi Chen ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Oxygen Vacancies ◽  
Separation Efficiency ◽  
Photocatalytic Property ◽  
Pure Hydrogen ◽  
Photogenerated Carrier ◽  
Surface Oxygen ◽  
Photoluminescence Spectra ◽  
Electron Hole ◽  
Insight Into

Oxygen vacancies (OVs) have critical effects on the photoelectric characterizations and photocatalytic activity of nanoceria, but the contributions of surface OVs on the promoted photocatalytic properties are not clear yet. In this work, we synthesized ceria nanopolyhedron (P-CeO2), ceria nanocube (C-CeO2) and ceria nanorod (R-CeO2), respectively, and annealed them at 600 °C in air, 30%, 60% or pure H2. After annealing, the surface OVs concentration of ceria elevates with the rising of H2 concentration. Photocatalytic activity of annealed ceria is promoted with the increasing of surface OVs, the methylene blue photodegradation ratio with pure hydrogen annealed of P-CeO2, C-CeO2 or R-CeO2 is 93.82%, 85.15% and 90.09%, respectively. Band gap of annealed ceria expands first and then tends to narrow slightly with the rising of surface OVs, while the valence band (VB) and conductive band (CB) of annealed ceria changed slightly. Both of photoluminescence spectra and photocurrent results indicate that the separation efficiency of photoinduced electron-hole pairs is significantly enhanced with the increasing of the surface OVs concentration. The notable weakened recombination of photogenerated carrier is suggested to attribute a momentous contribution on the enhanced photocatalytic activity of ceria which contains surface OVs.

scholarly journals Bi/BiOCl Nanosheets Enriched with Oxygen Vacancies to Enhance Photocatalytic CO2 Reduction

2021 ◽  
Author(s):  
Shuqi Wu ◽  
Junbu Wang ◽  
Qingchuan Li ◽  
Zeai Huang ◽  
Zhiqiang Rao ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Noble Metals ◽  
Oxygen Vacancies ◽  
Separation Efficiency ◽  
Co2 Reduction ◽  
Photogenerated Electron ◽  
In Situ Reduction ◽  
Electron Hole

AbstractBiOCl has been used in the photoreduction of CO2, but exhibits limited photocatalytic activity. In this study, Bi was in situ reduced and deposited on the surface of (001)-dominated BiOCl nanosheets by NaBH4 to form Bi/BiOCl nanosheets enriched with oxygen vacancies. The as-prepared Bi/BiOCl nanosheets having low thickness (ca. 10 nm) showed much higher concentration of oxygen vacancies compared to Bi/BiOCl nanoplates having high thickness (ca. 100 nm). Subsequently, the photocatalytic activity of the Bi/BiOCl nanosheets enriched with oxygen vacancies for CO2 reduction was dramatically enhanced and much higher than that of BiOCl nanoplates, nanosheets, and Bi/BiOCl nanoplates. It showed that the improved photocatalytic activity in the reduction of CO2 can be attributed to the enhanced separation efficiency of photogenerated electron–hole pairs of the oxygen vacancies on BiOCl nanosheets and Bi metals. This work demonstrated that the in situ reduction of non-noble metals on the surface of BiOCl nanosheets that are enriched with oxygen vacancies is favorable for increasing photocatalytic CO2 reduction.

scholarly journals Ag as Cocatalyst and Electron-Hole Medium in CeO2 QDs/Ag/Ag2Se Z-scheme Heterojunction Enhanced the Photo-Electrocatalytic Properties of the Photoelectrode

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 253 ◽  
Author(s):  
Lingwei Li ◽  
Hange Feng ◽  
Xiaofan Wei ◽  
Kun Jiang ◽  
Shaolin Xue ◽  
...  
Keyword(s):  
High Speed ◽  
Oxygen Vacancies ◽  
Photocatalytic Performance ◽  
Interfacial Region ◽  
Photogenerated Carrier ◽  
Electron Hole ◽  
Carrier Recombination ◽  
Photocatalytic System ◽  
Nano Channel ◽  
Active Substances

A recyclable photoelectrode with high degradation capability for organic pollutants is crucial for environmental protection and, in this work, a novel CeO2 quantum dot (QDs)/Ag2Se Z-scheme photoelectrode boasting increased visible light absorption and fast separation and transfer of photo-induced carriers is prepared and demonstrated. A higher voltage increases the photocurrent and 95.8% of tetracycline (TC) is degraded by 10% CeO2 QDs/Ag2Se in 75 minutes. The degradation rate is superior to that achieved by photocatalysis (92.3% of TC in 90 min) or electrocatalysis (27.7% of TC in 90 min). Oxygen vacancies on the CeO2 QDs advance the separation and transfer of photogenerated carriers at the interfacial region. Free radical capture tests demonstrate that •O2−, •OH, and h+ are the principal active substances and, by also considering the bandgaps of CeO2 QDs and Ag2Se, the photocatalytic mechanism of CeO2 QDs/Ag2Se abides by the Z-scheme rather than the traditional heterojunction scheme. A small amount of metallic Ag formed in the photocatalysis process can form a high-speed charge transfer nano channel, which can greatly inhibit the photogenerated carrier recombination, improve the photocatalytic performance, and help form a steady Z-scheme photocatalysis system. This study would lay a foundation for the design of a Z-scheme solar photocatalytic system.

Fabrication, characterization and photocatalytic activity of g-C3N4 coupled with FeVO4 nanorods

RSC Advances ◽  
2015 ◽  
Vol 5 (35) ◽  
pp. 27933-27939 ◽  
Author(s):  
Qingyan Nong ◽  
Min Cui ◽  
Hongjun Lin ◽  
Leihong Zhao ◽  
Yiming He
Keyword(s):  
Photocatalytic Activity ◽  
Separation Efficiency ◽  
Photogenerated Electron ◽  
Electron Hole

The coupling of FeVO4 nanorods with g-C3N4 promotes the separation efficiency of photogenerated electron–hole pairs, and subsequently enhances its photocatalytic activity in rhodamine photodegradation.

Synthesis of Er-doped Bi2WO6 and enhancement in photocatalytic activity induced by visible light

RSC Advances ◽  
2015 ◽  
Vol 5 (115) ◽  
pp. 94887-94894 ◽  
Author(s):  
Meng Wang ◽  
Ziyu Qiao ◽  
Minghao Fang ◽  
Zhaohui Huang ◽  
Yan'gai Liu ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Separation Efficiency ◽  
Photogenerated Electron ◽  
Electron Hole ◽  
Er Doped

1.5% Bi2WO6:Er3+ exhibited highest photocatalytic activity as the separation efficiency of the photogenerated electron–hole pairs is enhanced.

Photo-Induced Charge Transfer on Pt/Bi2WO6 Composite Photocatalysts

2020 ◽  
Vol 20 (3) ◽  
pp. 1838-1844 ◽  
Author(s):  
Dong-Qing He ◽  
Hong-Cheng Liu ◽  
Qi Wang ◽  
Qian Yu ◽  
Jin-Ying Liu ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Charge Transfer ◽  
Separation Efficiency ◽  
Pt Nanoparticles ◽  
Transient Photovoltage ◽  
Composite Photocatalysts ◽  
Induced Charge ◽  
Average Size ◽  
Transfer Properties ◽  
Insight Into

Pt/Bi2WO6 composite photocatalysts were prepared by a facile photoreduction method. Pt nanoparticles with an average size of 5–8 nm were successfully deposited on the surface of Bi2WO6 microspheres and the photocatalytic activity of Bi2WO6 was greatly improved by Pt nanoparticles. The photo-induced charge transfer properties of samples were studied by means of surface photovoltage (SPV) and transient photovoltage (TPV) techniques, giving an insight into the intrinsic reasons of the improvement in photocatalytic activity. The SPV and TPV results revealed that the deposited Pt nanoparticles could trap photo-induced electrons and then largely enhance the separation efficiency of photo-induced charge carriers.

Synthesis and High Visible Light Photocatalytic Activity of Ternary Brookite-g-C3N4-BiOBr Composite

NANO ◽  
2020 ◽  
Vol 15 (04) ◽  
pp. 2050045
Author(s):  
Ning Liu ◽  
Huidong Xie ◽  
Jie Li ◽  
Yajuan Zhao ◽  
Na Wang
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Rhodamine B ◽  
Separation Efficiency ◽  
Photogenerated Electron ◽  
Photocurrent Density ◽  
Electron Hole ◽  
Degradation Ratio ◽  
Loading Amount ◽  
Visible Light Photocatalytic

Brookite TiO2 was synthesized by a hydrothermal method, g-C3N4 was prepared by a pyrolytic method, brookite/g-C3N4 composites were prepared by a calcining method, and brookite/g-C3N4/BiOBr ternary composites were prepared by loading BiOBr on the surface of brookite/g-C3N4. XRD and XPS analysis of the composites confirmed the formation of brookite TiO2/g-C3N4/BiOBr. SEM and TEM results confirmed the as-prepared composites were nanosized. The optimum loading amount of BiOBr was 30%. The photocatalytic results showed that the brookite/g-C3N4/30%BiOBr composites degraded rhodamine B completely under visible light irradiation. The degradation ratio of brookite/g-C3N4/30%BiOBr toward rhodamine B was nearly 100% for 2[Formula: see text]h, which was much higher than that of brookite TiO2 and brookite/g-C3N4 catalysts. The reason for the improvement of photocatalytic activity might be because the composites promoted the formation of superoxide radicals and the separation efficiency of photogenerated electron-hole pairs. The photocurrent density of the brookite/g-C3N4/30%BiOBr was about 10 times higher than that of pure brookite. In addition, the brookite/g-C3N4/BiOBr showed a good repeatablity of photocatalysis.

A simple method to synthesise Ag-doped TiO2 photocatalysts with different Ag0:Ag2O atomic ratios for enhancing visible-light photocatalytic activity

2017 ◽  
Vol 41 (8) ◽  
pp. 475-483 ◽  
Author(s):  
C. Chen ◽  
X. F. Lei ◽  
M. Z. Xue
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Light Absorption ◽  
Separation Efficiency ◽  
Visible Region ◽  
Light Irradiation ◽  
Electron Hole ◽  
X Ray

Pure anatase TiO2 photocatalysts with different Ag contents were prepared via a simple sol-gel method. The as-prepared anatase Ag-doped TiO2 photocatalysts were characterised by X-ray diffraction, transmission electron microscopy, UV-Vis diffuse reflectance spectra, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, thermal gravity and differential thermal analysis, scanning electron microscopy and N2 adsorption–desorption measurements (BET). Compared with pure TiO2, Ag-doped anatase TiO2 photocatalysts exhibited not only increases in light absorption in the visible region, the separation efficiency of electron–hole pairs and surface area, but also inhibition of the titania phase transition from anatase to rutile. Photoreduction results showed that Ag-doped anatase TiO2 photocatalysts have greatly improved photocatalytic activity, compared with pure TiO2, and the reduction of Cr(VI) under visible light irradiation was much higher than that of pure TiO2. The optimum Ag content was 1.0 mol%, which led to the complete reduction of Cr(VI) under visible light irradiation (λ > 420 nm) for 4 h. The enhanced photocatalytic activity was attributed to the synergic effect of the pure anatase structure, and the increased light absorption in the visible region, separation efficiency of electron–hole pairs and atomic ratio of Ag0:Ag2O.

The effect of iron doping on the photocatalytic activity of a Bi2WO6–BiVO4composite

RSC Advances ◽  
2016 ◽  
Vol 6 (59) ◽  
pp. 54060-54068 ◽  
Author(s):  
Saranyoo Chaiwichian ◽  
Khatcharin Wetchakun ◽  
Sukon Phanichphant ◽  
Wiyong Kangwansupamonkon ◽  
Natda Wetchakun
Keyword(s):  
Photocatalytic Activity ◽  
Separation Efficiency ◽  
Photogenerated Electron ◽  
Iron Doping ◽  
Electron Hole

The formation of Fe-doped Bi2WO6–BiVO4composites could improve the separation efficiency of photogenerated electron–hole pairs, then increasing its photocatalytic activity.

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