Suppression of Surface Recombination on TiO<sub>2</sub> Anatase Photocatalysts in Aqueous Solutions Containing Alcohol

Semenikhin, Oleg A.; Kazarinov, V.E.; Jiang, Lei; Hashimoto, Kazuhito; Fujishima, Akira

doi:10.1021/la981437b

Cited by 38 publications

(40 citation statements)

References 24 publications

(76 reference statements)

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“…This mechanism has been discussed many times for the effect of electron-donating additives on the photocatalytic reactions with a suspension of the microparticles of broadband semiconductors [8].…”

Section: Resultsmentioning

confidence: 99%

Photocatalytic activity of nanoparticles of metal sulfides in the degradation of organic dyes

2006

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The photocatalytic degradation of dyes at the nanosized sulfides of transition metals in aqueous solutions was investigated. The rate of degradation increases with decrease in the synthesis temperature of the nanoparticles and with the addition of alcohol. The substitution of Cd 2+ cations by Ag + or Cu 2+ leads to a decrease in the photoactivity of the CdS, while substitution by In 3+ leads to an increase. The substitution of Ni 2+ and Co 2+ cations in the corresponding sulfides by Cd 2+ leads to an increase in the rate of degradation.Nanoparticles containing oxides, sulfides, and other inorganic compounds can exhibit high photocatalytic activity in synthesis, reforming, degradation, and other reactions of organic compounds [1][2][3][4]. Nanoparticles as photocatalysts have a substantial advantage over the microparticles formed by broadband semiconductors such as TiO 2 , ZrO 2 , ZnO, Fe 2 O 3 , etc. due to the fact that they do not scatter light, making it possible to utilize more fully the incident light.The initial process in photocatalysis at suspensions of broadband photocatalysts is the formation of hole (h + )/electron (e -) pairs, which can recombine or dissociate with the release of h + and e -to the surface of the catalyst particles [5]. The holes and electrons can interact with the substrates and also with molecular oxygen or surface hydroxyls, leading to the formation of highly reactive particles, the reaction of which with the substrates causes degradation of the latter.The present paper is devoted to an investigation into the photocatalytic characteristics of the nanoparticles formed by the sulfides of transition metals, including mixed sulfides, as illustrated by the degradation of dyes. A comparative study was made of the photocatalytic characteristics of cadmium, nickel, silver, manganese, copper, cobalt, and molybdenum sulfide nanoparticles. EXPERIMENTALThe nanoparticles were prepared in aqueous solutions of the salts (5×10 -3 M) (chlorides, sulfates, or nitrates) of the respective metals by the usual procedure [6]. Ammonium molybdate was used for the preparation of the MoS 3 nanoparticles. During the preparation of the nanoparticles a stabilizer in the form of sodium polyphosphate (sodium hexametaphosphate) or methylbenzethonium chloride (Aldrich) was added to the solution of the salt, and an equimolar amount of sodium sulfide was then added with vigorous stirring. In the photocatalytic experiments the concentration of the stabilizer was 2 g/L. 2820040-5760/06/4205-0282

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Section: Resultsmentioning

confidence: 99%

Photocatalytic activity of nanoparticles of metal sulfides in the degradation of organic dyes

2006

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“…They attributed this to direct capture of holes by the adsorbed organic. An earlier, more detailed analysis was reported by Fujishima and co-workers [28] for the specific case of methanol. Fujishima and coworkers interpreted their results in terms of a model in which at low overpotentials (i.e.…”

Section: Electrochemical Characterization Of the Photoanodes And The mentioning

confidence: 88%

“…Since the Vinodgopal model [27] requires relatively high surface area, porous, particulate films that are readily accessible to the electrolyte, we speculate that the photocurrent enhancement on addition of methanol requires both anatase crystallites and porous films and is essentially blocked by rutilization. However, such enhancement has also been seen with single crystal rutile TiO 2 and zinc oxide [28].…”

Section: Structural Characterization Of the Photoanodesmentioning

confidence: 94%

The photoelectrocatalytic oxidation of aqueous nitrophenol using a novel reactor

et al. 2005

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This paper reports the oxidation of aqueous 4-nitrophenol solutions in a photo-electrochemical bubble column reactor (BCR) in which mass transfer has been shown not to be rate limiting. The work represents the first steps in the scale-up of active photoanodes and efficient reactors for the disinfection and detoxification of water.The preparation, optimization and application of two types of electrode are described and the results are compared with those for a TiO 2 electrode supplied by Ineos Chlor. Photocurrents measured in tap water and in aqueous methanol were used for the initial characterization of the electrodes. The methanol was employed for diagnostic purposes only, as discussed below; methanol can react either by direct hole transfer or by hydroxyl radical recombination, but the balance of these reactions depends upon the nature of the electrode surface. The most active thermal electrodes were fabricated by heating titanium metal in air at 750°C for 10 min, whilst the most active solgel electrodes were heated at 600°C for 10 min.Three of the central achievements of the work were to: (1) show that it is possible to design and fabricate photoelectrochemical reactors capable of effecting the mineralization of strongly absorbing organics; (2) confirm that the photocatalytic decomposition of 4-NP in reactors with a 4 dm 3 capacity can be increased by the application of a small positive potential and (3) that the application of such a potential significantly enhances the mineralization of 4-NP.For the mineralization of 0.25 mM nitrophenol solutions the reactivity sequence is:However, even at 3 V applied potential, charge recombination is not eliminated. The order of electrode activity was:Ineos > Sol Gel > Thermal: Differences between the activities of different electrodes were attributed to changes in the structure and morphology of the TiO 2 . It is noteworthy that although, for nitrophenol oxidation, the thermal electrodes were the least active, for photoelectrocatalytic disinfection in the same type of reactor, thermal electrodes were the most active.

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“…There is very important relationship between photocatalytic activity and interaction of contamination and photocatalyst (Linsebigler et al 1995;Semenikhin et al 1999;Rothenberger et al 1985). From some other researches (Dubey et al 2006), it can be seen that adsorbing organics on the surface of photocatalyst is helpful to prevent recombination of photoinduced electrons and holes.…”

Section: Adsorption Of Mo On the Surface Of Pth/tio 2 Composite Partimentioning

confidence: 99%

Visible Light Induced Photocatalytic Degradation of Methyl Orange by Polythiophene/TiO2 Composite Particles

Zhu

Jiang

et al. 2010

Water Air Soil Pollut

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The adsorption and photocatalytic degradation of methyl orange (MO) aqueous solution under visible light illumination by polythiophene/titanium dioxide (PTh/TiO 2 ) composite particles were studied. The experimental observations from UV-vis spectrophotometer indicate that MO molecules were degraded in a different degree during the visible light-induced photocatalysis reaction. We propose a new degradation mechanism of MO during the photocatalytic reaction, based on blue shift of UV-vis absorption spectra of MO solution and other researches. The data from total organic carbon analyzer definitely prove that MO can be mineralized to CO 2 and H 2 O, and some intermediate products are generated during the photocatalysis degradation of MO.

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Suppression of Surface Recombination on TiO₂ Anatase Photocatalysts in Aqueous Solutions Containing Alcohol

Cited by 38 publications

References 24 publications

Photocatalytic activity of nanoparticles of metal sulfides in the degradation of organic dyes

Photocatalytic activity of nanoparticles of metal sulfides in the degradation of organic dyes

The photoelectrocatalytic oxidation of aqueous nitrophenol using a novel reactor

Visible Light Induced Photocatalytic Degradation of Methyl Orange by Polythiophene/TiO2 Composite Particles

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Suppression of Surface Recombination on TiO2 Anatase Photocatalysts in Aqueous Solutions Containing Alcohol

Cited by 38 publications

References 24 publications

Photocatalytic activity of nanoparticles of metal sulfides in the degradation of organic dyes

Photocatalytic activity of nanoparticles of metal sulfides in the degradation of organic dyes

The photoelectrocatalytic oxidation of aqueous nitrophenol using a novel reactor

Visible Light Induced Photocatalytic Degradation of Methyl Orange by Polythiophene/TiO2 Composite Particles

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Suppression of Surface Recombination on TiO₂ Anatase Photocatalysts in Aqueous Solutions Containing Alcohol