scholarly journals Tuning the Photocatalytic Activity of Tin Oxide Through Mechanical Surface Activation

Author(s):  
Fernando Silva ◽  
Gelson da Silva ◽  
Juliana Torres ◽  
Caue Ribeiro

Tin oxide (SnO2) nanoparticles were synthesized by the co-precipitation method and mechanically modified by high-energy ball milling. The experimental results demonstrate that the collision with zirconia balls produces slight changes in the crystalline, electronic, morphological, and surface properties of SnO2, which lead to an increase in the redox potential of the energy level and the formation of the hydroxyl group on the SnO2 surface. Moreover, these changes are intensified over the milling up to 90 min, directly affecting the photocatalytic performance, which was monitored by the rate of rhodamine B (RhB) degradation driven by ultraviolet (UV) irradiation. As a result, all ground samples showed better photocatalytic activity than pristine SnO2 (Sn-cop). The maximum degradation of rhodamine B was ca. 75%, achieved with 90 min-milled SnO2 nanoparticles (Sn-M90), compared to the Sn-cop sample induced a 1.67 times higher degradation rate. The reaction mechanism suggests that its better photocatalytic activity may be associated with the higher increased redox potential of the valence and conduction bands and the formation of hydroxyl active sites on the catalyst surface principal oxidizing agent generated. Therefore, we conclude that the ball milling process is an efficient way to induce stable activation of oxide metal for photocatalytic applications.

Author(s):  
Fengjuan Ge ◽  
Jie Zhu ◽  
Yan Xu ◽  
Jing Li ◽  
Xueyang Zhang

BiOBr photocatalysts were prepared by changing the solvent and synthesis method. SEM, XRD and BET characterization shows that the sample prepared in high-viscosity solution by precipitation method has tremella-like microstructure, with smaller size and higher surface area. Among them, the BiOBr prepared in glycerol solution (GR-P) has the highest surface area of 113.8 m2⋅[Formula: see text]. XRD also indicates that the GR-P has much more exposed (110) facets than other samples. The Rhodamine B degradation tests show that the GR-P has the best activity on both deethylation and aromatic ring destruction steps, indicating that the exposed (110) facets promote the degradation process.


Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5889
Author(s):  
Jeyapaul Sam Jebakumar ◽  
Asokan Vimala Juliet

The exhaust gases from various sources cause air pollution, which is a leading contributor to the global disease burden. Hence, it has become vital to monitor and control the increasing pollutants coming out of the various sources into the environment. This paper has designed and developed a sensor material to determine the amount of carbon monoxide (CO), which is one of the major primary air pollutants produced by human activity. Nanoparticle-based sensors have several benefits in sensitivity and specificity over sensors made from traditional materials. In this study, tin oxide (SnO2), which has greater sensitivity to the target gas, is selected as the sensing material which selectively senses only CO. Tin oxide nanoparticles have been synthesized from stannous chloride dihydrate chemical compound by chemical precipitation method. Palladium, at the concentration of 0.1%, 0.2%, and 0.3% by weight, was added to tin oxide and the results were compared. Synthesized samples were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) techniques. XRD revealed the tetragonal structure of the SnO2 nanoparticles and FESEM analysis showed the size of the nanoparticles to be about 7–20 nm. Further, the real-time sensor testing was performed and the results proved that the tin oxide sensor, doped with 0.2% palladium, senses the CO gas more efficiently with greater sensitivity.


2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
H. Letifi ◽  
Y. Litaiem ◽  
D. Dridi ◽  
S. Ammar ◽  
R. Chtourou

In this paper, we have reported a novel photocatalytic study of vanadium-doped SnO2 nanoparticles (SnO2: V NPs) in rhodamine B degradation. These NPs have been prepared with vanadium concentrations varying from 0% to 4% via the coprecipitation method. Structural, morphological, and optical properties of the prepared nanoparticles have been investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscope (TEM), and UV-Vis and photoluminescence (PL) spectroscopy. Structural properties showed that both undoped and SnO2: V NPs exhibited the tetragonal structure, and the average crystal size has been decreased from 20 nm to 10 nm with the increasing doping level of vanadium. Optical studies showed that the absorption edge of SnO2: V NPs showed a redshift with the increasing vanadium concentration. This redshift leads to the decrease in the optical band gap from 3.25 eV to 2.55 eV. A quenching in luminescence intensity has been observed in SnO2: V NPs, as compared to the undoped sample. Rhodamine B dye (RhB) has been used to study the photocatalytic degradation of all synthesized NPs. As compared to undoped SnO2 NPs, the photocatalytic activity of SnO2: V NPs has been improved. RhB dye was considerably degraded by 95% within 150 min over on the SnO2: V NPs.


2020 ◽  
Vol 6 (1) ◽  
pp. 1-9
Author(s):  
Febiyanto Febiyanto ◽  
Uyi Sulaeman

Synthesis of Ag3PO4 photocatalyst under the varied concentrations of AgNO3 and Na2HPO4·12H2O as starting material has been successfully synthesized using the co-precipitation method. The concentration of AgNO3 is 0.1; 0.5; 1.0; and 2.0 M, whereas Na2HPO4·12H2O is 0.03; 0.17; 0.33; and 0.67 M, respectively. The co-precipitations were carried out under aqueous solution. As-synthesized photocatalysts were examined to degrade Rhodamine B (RhB) under blue light irradiation. The results showed that varying concentrations of starting materials affect the photocatalytic activities, the intensity ratio of [110]/[200] facet plane, and their bandgap energies of Ag3PO4 photocatalyst. The highest photocatalytic activity of the sample was obtained by synthesized using the 1.0 M of AgNO3 and 0.33 M of Na2HPO4·12H2O (AP-1.0). This is due to the high [110] facet plane and increased absorption along the visible region of AP-1.0 photocatalyst. Therefore, this result could be a consideration for the improvement of Ag3PO4 photocatalyst.


Author(s):  
Mukholit, Heri Sutanto ◽  
Ngurah Ayu Ketut Umiati ◽  
Eko Hidayanto

Bi2O3 has successfully been synthesized using precipitation method with sintering temperature variations of 400oC, 450o C, 500o C, 550o C, and 600o C. Crystallinity property of resulting Bi2O3 powder has also been tested with XRD and morphology properties were tested with SEM. Meanwhile, photocatalytic properties were tested by using it to degrade Rhodamine B under sunlight. Results of XRD tests show that differences in sintering temperature affect crystallite size. Increases in sintering temperature between 400o C and 500o C result in greater crystallite size, whereas sintering temperature between 550o C and 600oC result in smaller crystallite size. Results of SEM tests show that resulting Bi2O3 has rod-like structure, While results of degradation tests show that increases in sintering temperature enhances photocatalytic activities of Bi2O3, as evident with Bi2O3 undergoing sintering at 600oC was able to degrade Rhodamine B with 56.74% effectiveness and degradation rate of 0.007 ppm/min.


2009 ◽  
Vol 207 (2-3) ◽  
pp. 231-235 ◽  
Author(s):  
Roger Amade ◽  
Paul Heitjans ◽  
Sylvio Indris ◽  
Mina Finger ◽  
Andreas Haeger ◽  
...  

Author(s):  
Sivakumar Krishnamoorthy ◽  
Dharani M.

Zinc oxide (ZnO) nanoparticles prepared using simple co-precipitation method are characterized and photocatalytic activity is tested on the degradation of methylene blue and rhodamine B organic pollutants. Morphological and structural properties of synthesized nanomaterial have been characterized using FESEM, EDAX spectroscopy, and XRD, while UV-visible DRS spectroscopy and photoluminescence have been used to understand their optical properties. The photocatalytic behaviour of synthesized nanoparticles was evaluated on the degradation of methylene blue (MB) and rhodamine B (RhB) organic pollutants under solar light irradiation. The highest degradation was achieved for MB (100%) over RhB (96%). Preliminary investigation shows the effective degradation of organic pollutants by ZnO nanoparticles.


2016 ◽  
Vol 8 (3) ◽  
pp. 399-411 ◽  
Author(s):  
M. T. Uddin ◽  
Y. Sultana ◽  
M. A. Islam

In the present study, tin oxide (SnO2) nanoparticles were prepared by precipitation method using tin tetrachloride (SnCl4) as precursor and ammonia solution as precipitating agent followed by calcination at 400 ºC for 2 h. As-prepared SnO2 particles were characterized by X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR). The powder XRD results revealed that the SnO2 nanoparticles had a typical tetragonal rutile (cassiterite) structure and the average crystallite size calculated by using the Debye –Scherrer equation was found to be approximately 5.1 nm. The photocatalytic activity of the as-prepared photocatalysts was investigated by degrading methylene blue (MB) dye. The effect of pH, catalyst loading and initial dye concentration on photocatalytic degradation was investigated. Results showed that the SnO2 nanoparticles represented excellent photocatalytic activity for the degradation of MB under UV light with 200 min of irradiation time. The results also showed that the pH of solution had a direct influence on the photocatalysis process and basic pH was favorable for the degradation of MB. The effect of pH on photocatalytic activity was explained with the help of zero point charge (pHpzc). Furthermore, the photocatalysts could be easily recycled without significant change in the catalytic activity.


Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 139 ◽  
Author(s):  
Mohamed Mahmoud ◽  
Moaaed Motlak ◽  
Nasser Barakat

SnO2-decorated graphene oxide (SnO2/GO) was synthesized by the modified Hummers’s method, followed by a chemical incorporation of SnO2 nanoparticles. Then, the nanocomposite was used as anon-precious counter electrode in a dye-sensitized solar cell (DSSC). Although GO has a relatively poor electrical conductivity depending essentially on the extent of the graphite oxidation, presence of SnO2 enhanced its structural and electrochemical properties. The Pt-free counter electrode exhibited a distinct catalytic activity toward iodine reduction and a low resistance to electron transfer. Moreover, the decorated GO provided extra active sites for reducing I3− at the interface of the CE/electrolyte. In addition, the similarity of the dopant in the GO film and the fluorine-doped tin oxide (FTO) substrate promoted a strong assimilation between them. Therefore, SnO2-decorated GO, as a counter electrode, revealed an enhanced photon to electron conversion efficiency of 4.57%. Consequently, the prepared SnO2/GO can be sorted as an auspicious counter electrode for DSSCs.


Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1603 ◽  
Author(s):  
Meiling Sun ◽  
Weichong Kong ◽  
Yunlong Zhao ◽  
Xiaolin Liu ◽  
Jingyue Xuan ◽  
...  

Herein, high-energy {001} facets and Sn4+ doping have been demonstrated to be effective strategies to improve the surface characteristics, photon absorption, and charge transport of TiO2 hierarchical nanospheres, thereby improving their photocatalytic performance. The TiO2 hierarchical nanospheres under different reaction times were prepared by solvothermal method. The TiO2 hierarchical nanospheres (24 h) expose the largest area of {001} facets, which is conducive to increase the density of surface active sites to degrade the adsorbed methylene blue (MB), enhance light scattering ability to absorb more incident photons, and finally, improve photocatalytic activity. Furthermore, the SnxTi1−xO2 (STO) hierarchical nanospheres are fabricated by Sn4+ doping, in which the Sn4+ doping energy level and surface hydroxyl group are beneficial to broaden the light absorption range, promote the generation of charge carriers, and retard the recombination of electron–hole pairs, thereby increasing the probability of charge carriers participating in photocatalytic reactions. Compared with TiO2 hierarchical nanospheres (24 h), the STO hierarchical nanospheres with 5% nSn/nTi molar ratio exhibit a 1.84-fold improvement in photodegradation of MB arising from the enhanced light absorption ability, increased number of photogenerated electron–hole pairs, and prolonged charge carrier lifetime. In addition, the detailed mechanisms are also discussed in the present paper.


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