Probing the tunneling of electrons from SnO2 to ZnO in dye sensitization of composite SnO2/ZnO by use of generated H2O2 via reduction of O2

Bandara, Jayasundera; Tennakone, K.; Binduhewa, Prabath

doi:10.1039/b101411k

Cited by 10 publications

(7 citation statements)

References 14 publications

(3 reference statements)

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“…In order to assess the nature of photocatalytic degradation of R6G, we analysed the emission spectra of ZnO and silver modified ZnO in presence of R6G which is shown in Figure 10. The high reduction potential of S*, CB of ZnO (-0.8 V Vs NHE) and of Ag (0.15V) (according to literature data) 66,67 drives its electron injection reactions.…”

Section: Mechanism Of Enhancement Of Photocatalytic Activity By Silvermentioning

confidence: 99%

A Highly Efficient Ag-ZnO Photocatalyst: Synthesis, Properties, and Mechanism

2008

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Highly photocatalytically active silver-modified ZnO has been prepared and the effect of silver modification was studied. The structural and optical properties were characterized by X-ray diffraction, Fourier transform IR, differential scanning calorimetry, BET surface area, Raman, UV-vis, and photoluminescence spectroscopy. The photocatalytic activity of these materials was studied by analyzing the degradation of an organic dye, rhodamine 6G (R6G), and it is found that 3 mol % silver-modified ZnO at 400 °C shows approximately four times higher rate of degradation than that of unmodified ZnO and a three times higher rate than that of commercial TiO 2 photocatalyst Degussa P-25. It was also noted that the photocatalytic activity for the modified ZnO sample was five times higher than the unmodified sample using sunlight. The effect of silver in enhancing the photocatalytic activity has been studied by analyzing the emission properties of both ZnO and silvermodified ZnO in the presence (emission increases) and absence (emission decreases) of R6G. We attribute these observations to the extent of valence band hole production and the role of silver in trapping the conduction band (CB) electrons in the absence of R6G. In the presence of R6G, the dye preserves the CB electron population in the metal oxide, thus preserving and enhancing emission intensity. The sensitizing property of the dye and electron scavenging ability of silver together constitute to the interfacial charge transfer process in such a way to utilize the photoexcited electrons.

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Section: Mechanism Of Enhancement Of Photocatalytic Activity By Silvermentioning

confidence: 99%

A Highly Efficient Ag-ZnO Photocatalyst: Synthesis, Properties, and Mechanism

2008

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“…This enhances the photocatalytic efficiency, and there are many examples for coupled semiconductorphotocatalysis [4,5,[7][8][9]12,21]. In the reported coupled semiconductor-photocatalysis, both the semiconductors are bound together to form a particle and charge separation occurs within the particle.…”

Section: Enhanced Photocatalysis By Particulate Semiconductor Mixturementioning

confidence: 99%

“…TiO 2 /CdS powder as well as electrode, obtained by deposition of CdS on TiO 2 , exhibits higher photoactivity than bare TiO 2 powder and electrode [4]. Composite SnO 2 /ZnO generates more H 2 O 2 than individual oxides under dye-sensitization [5]. CuO/TiO 2 , obtained by coating TiO 2 on quartz followed by wet impregnation of CuO, photodegrades NO [6].…”

Section: Introductionmentioning

confidence: 99%

Semiconductor‐photocatalyzed degradation of carboxylic acids: Enhancement by particulate semiconductor mixture

Karunakaran

Dhanalakshmi

Gomathisankar

2009

Int J of Chemical Kinetics

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Degradation of oxalic acid on particulate TiO 2 , ZnO, CuO, Bi 2 O 3 , In 2 O 3 , and Nb 2 O 5 under UV-A light exhibits first-order kinetics, and the degradation rates increase linearly with the photon flux. All the oxides show sustainable photocatalytic activity, and the photonic efficiencies of degradation of oxalate are very much lower than those of the acid. The ease of degradation of carboxylic acids is the following: formic > oxalic > acetic > citric. Intimate mixtures of two different particulate semiconductors kept under suspension and at continuous motion exhibit higher photocatalytic activity, revealing interparticle charge transfer. C 2009

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“…Moreover, the present study shows that the degradation on Y 2 O 3 is enhanced by semiconductors, an unusual synergism when a semiconductor is present along with an insulator. Interparticle charge-transfer between semiconductors is known; a couple of reports are on charge-transfer between two particulate semiconductors [19,20] and the rest deal with coupled semiconductors [21,22]. …”

Section: Introductionmentioning

confidence: 99%