scholarly journals Enhanced visible-light photocatalytic activity of anatase-rutile mixed-phase nano-size powder given by high-temperature heat treatment

2020 ◽  
Vol 7 (1) ◽  
pp. 191539 ◽  
Author(s):  
Takamasa Ishigaki ◽  
Yusuke Nakada ◽  
Naoki Tarutani ◽  
Tetsuo Uchikoshi ◽  
Yoshihiro Tsujimoto ◽  
...  

Nano-size EVONIK AEROXIDE ® P25 titanium dioxide, TiO 2 , powder was heat-treated at temperatures, 700–900°C, in air. An X-ray diffraction study showed that the P25 powder is composed of approximately 20 and approximately 80 mass% of rutile and anatase phases, respectively. It was also shown that the transformation from anatase to rutile induced by high-temperature heat treatment was almost completed at 750°C, whereas a small amount (less than 3 mass%) of anatase phase was still left even in the powder heat-treated at 900°C. The transformation behaviour was consistent with results obtained by Raman scattering spectroscopy. Raman experiments also indicated that high-temperature heating induced the formation of oxide ion vacancies. Powders were dispersed in methyl orange (MO) aqueous solution, and the bleach rate of MO was measured to evaluate photocatalytic activity under ultraviolet (UV)- and visible-light irradiation. After the heat treatment, the UV-light photocatalytic performance sharply deteriorated. Interestingly, visible-light photocatalytic activity was enhanced by high-temperature heating and reached the highest performance for an 800°C-heated sample, indicating that the P25 powder obtained high visible-light photocatalytic performance after heat treatment. Even after 900°C heat treatment, the photocatalytic performance was higher than that of as-received powder. Enhancement of photocatalytic activities was discussed in relation to visible light absorption and charge carrier transfer.

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3948
Author(s):  
Lingfang Qiu ◽  
Zhiwei Zhou ◽  
Mengfan Ma ◽  
Ping Li ◽  
Jinyong Lu ◽  
...  

Novel visible-light responded aluminosilicophosphate-5 (SAPO-5)/g-C3N4 composite has been easily constructed by thermal polymerization for the mixture of SAPO-5, NH4Cl, and dicyandiamide. The photocatalytic activity of SAPO-5/g-C3N4 is evaluated by degrading RhB (30 mg/L) under visible light illumination (λ > 420 nm). The effects of SAPO-5 incorporation proportion and initial RhB concentration on the photocatalytic performance have been discussed in detail. The optimized SAPO-5/g-C3N4 composite shows promising degradation efficiency which is 40.6% higher than that of pure g-C3N4. The degradation rate improves from 0.007 min−1 to 0.022 min−1, which is a comparable photocatalytic performance compared with other g-C3N4-based heterojunctions for dye degradation. The migration of photo-induced electrons from g-C3N4 to the Al site of SAPO-5 should promote the photo-induced electron-hole pairs separation rate of g-C3N4 efficiently. Furthermore, the redox reactions for RhB degradation occur on the photo-induced holes in the g-C3N4 and Al sites in SAPO-5, respectively. This achievement not only improves the photocatalytic activity of g-C3N4 efficiently, but also broadens the application of SAPOs in the photocatalytic field.


2017 ◽  
Vol 19 (36) ◽  
pp. 24915-24927 ◽  
Author(s):  
A. H. Reshak

The amalgamation of a wide optical band gap photocatalyst with visible-light-active CdO quantum dots (QDs) as sensitizers is one of the most efficient ways to improve photocatalytic performance under visible light irradiation.


Nanomaterials ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 579 ◽  
Author(s):  
Xiaojuan Chen ◽  
Ning Li ◽  
Runliang Zhu ◽  
Shuai Li ◽  
Chunmo Yu ◽  
...  

Novel Z-Scheme CuBi2O4/β-Bi2O3 composite photocatalysts with different mass ratios and calcination temperatures were firstly synthesized by the hydrothermal method following a temperature-programmed process. The morphology, crystal structure, and light absorption properties of the as-prepared samples were systematically characterized, and the composites exhibited enhanced photocatalytic activity toward diclofenac sodium (DS) degradation compared with CuBi2O4 and β-Bi2O3 under visible light irradiation. The optimal photocatalytic efficiency of the composite, achieved at the mass ratio of CuBi2O4 and β-Bi2O3 of 1:2.25 and the calcination temperature of 600 °C is 92.17%. After the seventh recycling of the composite, the degradation of DS can still reach 82.95%. The enhanced photocatalytic activity of CuBi2O4/β-Bi2O3 is closely related to OH•, h+ and O2•−, and the photocatalytic mechanism of CuBi2O4/β-Bi2O3 can be explained by the Z-Scheme theory.


RSC Advances ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 6114-6120 ◽  
Author(s):  
Junpeng Ren ◽  
Yongyong Zhu

Ag2O doped electrospun BiVO4 nanofibers with p–n junction heterogeneous structures show enhanced photocatalytic activity under visible light (photocatalytic efficiency: 98.47% within 100 min) and good cycling stability.


RSC Advances ◽  
2015 ◽  
Vol 5 (112) ◽  
pp. 92033-92041 ◽  
Author(s):  
Xin Liu ◽  
Ailing Jin ◽  
Yushuai Jia ◽  
Junzhe Jiang ◽  
Na Hu ◽  
...  

An efficient composite photocatalyst fabricated by dispersing ultrafine Fe2O3 nanocrystals onto g-C3N4 nanosheets via a facile deposition-precipitation method shows significantly enhanced photocatalytic performance under visible light irradiation.


2020 ◽  
Vol 100 (1) ◽  
pp. 165-174 ◽  
Author(s):  
Piotr Micek ◽  
Katarzyna Słota ◽  
Paweł Górka

The aim of this study was to determine the effect of heat treatment alone or in combination with the addition of lignosulfonate (LSO3) on canola cake protein, lysine, and methionine degradation in the rumen. Cold-pressed canola cake was left untreated, heated at 90, 110, 130, or 150 °C, or processed with 5% of LSO3 (in dry matter) and then heated. Effective rumen degradability of crude protein (CP), lysine, and methionine was less for treated than untreated canola cake (P < 0.05) and decreased with increased temperature of heating, but particularly when canola cake was heated at 150 °C (quadratic, P < 0.01). In general, effective rumen degradability of CP, lysine, and methionine was less for canola cake heated at 130 °C in combination with LSO3 compared with canola cake heat treated only (quadratic × LSO3 interaction, P ≤ 0.07). Results of this study indicate that high temperature heating (130 °C or greater for 60 min) may be necessary to protect canola cake protein from degradation in the rumen, and the combination of heat treatment and LSO3 may be more effective in protecting canola cake protein, lysine, and methionine from degradation in the rumen than the use of heat treatment only.


CrystEngComm ◽  
2015 ◽  
Vol 17 (32) ◽  
pp. 6120-6126 ◽  
Author(s):  
Yajie Chen ◽  
Guohui Tian ◽  
Tong Feng ◽  
Wei Zhou ◽  
Zhiyu Ren ◽  
...  

Single-crystalline Bi19Br3S27 nanorods were prepared and showed excellent visible-light photocatalytic performance.


2015 ◽  
Vol 17 (43) ◽  
pp. 28743-28753 ◽  
Author(s):  
Guangzhao Wang ◽  
Hong Chen ◽  
Yang Li ◽  
Anlong Kuang ◽  
Hongkuan Yuan ◽  
...  

To improve the photocatalytic performance of KNbO3 for the decomposition of water into hydrogen and oxygen, the electronic structure of KNbO3 should be modified to have a suitable bandgap with band edge positions straddling the water redox level so as to sufficiently absorb visible light.


2014 ◽  
Vol 16 (26) ◽  
pp. 13409-13417 ◽  
Author(s):  
Chao Liu ◽  
Liang Wu ◽  
Jing Chen ◽  
Ji-yuan Liang ◽  
Chang-shun Li ◽  
...  

N-doping and intercalation resulted in a PANI–N-HTiNbO5lamellar nanocomposite, which showed a dramatic enhanced visible-light photocatalytic activity and stability for the degradation of methylene blue (MB), due to the high efficiency of charge separation.


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