Study of solid/gas phase photocatalytic reactions by electron ionization mass spectrometry

Nuño, Manuel; Ball, Richard; Bowen, Chris R.

doi:10.1002/jms.3396

Cited by 12 publications

(10 citation statements)

References 45 publications

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“…Anatase is one of the polymorphs and is widely studied for its photocatalytic properties when exposed to UV radiation. Previous researchers have investigated the use of titanium dioxide and its photocatalytic reactions in a wide range of applications such as water treatment [12][13][14], air purification [15][16][17][18][19] self-cleaning surfaces [20][21][22][23][24][25][26] or for the development of new super hydrophilic surfaces [21].…”

Section: Titanium Dioxide and Photocatalysismentioning

confidence: 99%

Environmental performance of nano-structured Ca(OH)2/TiO2 photocatalytic coatings for buildings

Nuño

Pesce

Bowen

et al. 2015

Building and Environment

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This paper describes the environmental performance of a mixed phase coating (photocatalytic nanolime) manufactured from a colloidal nano-structured calcium hydroxide in alcohol (nanolime) combined with titanium dioxide. While nanolime is used as a consolidant in the field of cultural heritage and titanium dioxide is used as a photocatalytic material for self-cleaning coatings and environmental pollution control within the construction industry both materials are often used separately. We report in this paper an approach to combine both materials for the development of a photocatalytic nanolime coating. The photocatalytic effect of titanium dioxide on the carbonation of nanolime and its influence on the degradation processes in polluted environments is explored. A suspension of 25g/l of nanolime in ethanol and 7.4% wt/vol titanium dioxide was applied to specimens of Bath stone. For comparison, additional specimens were treated only with the nanolime.The specimens were exposed to oxides of nitrogen and sulphur under 30% relative humidity (RH) for 120 hours. Exposure was carried out under both, UV and daylight. After exposure, the effect of titanium dioxide on the carbonation of nanolime and on the degradation processes was investigated using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and X-ray photo electron spectroscopy (XPS). Results were evaluated considering the dissolution processes of the two oxides in water, and modelled using PHREEQC. Results show that the nanolime and the photocatalytic nanolime coatings promote the reaction of SO 2 . In addition, the photocatalytic effect of the anatase form of titanium dioxide promotes the formation of a surface layer of calcium sulphate and inhibits carbonation of calcium hydroxide. That was attributed to the oxidation of sulphur dioxide to sulphur trioxide by hydroxyl radicals which led to the formation of sulphuric acid.

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Section: Titanium Dioxide and Photocatalysismentioning

confidence: 99%

Environmental performance of nano-structured Ca(OH)2/TiO2 photocatalytic coatings for buildings

Nuño

Pesce

Bowen

et al. 2015

Building and Environment

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“…To assess the photocatalytic activity of TiO 2 powders in the gas phase, a mass spectrometer was employed due to its ability to monitor a range of species simultaneously. The system has been reported previously in detail [14][15][16], including the ionic species and corresponding masses commonly formed in the gas phase [15]. A schematic diagram of the system is shown in Figure 1.…”

Section: Photocatalytic Degradation Of Gaseous Pollutantsmentioning

confidence: 99%

“…Gas cylinders are connected via flowmeters to the reactive chamber. One output is connected to the detector[15].…”

mentioning

confidence: 99%

Photocatalytic Properties of Commercially Available TiO2 Powders for Pollution Control

Nuño¹,

Ball²,

Bowen³

2016

Semiconductor Photocatalysis - Materials, Mechanisms and Applications

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The photocatalytic properties of titanium dioxide have been widely studied over recent decades since the discovery of water photolysis by TiO 2 electrodes in 1972. Titanium dioxide has three main crystal polymorphs; anatase, rutile and brookite and rutile is the most common as the metastable polymorph. Each polymorph has different band gap positions. Anatase's band gap is 3.2 eV, higher than rutile's which is 3.0 eV. This difference in the band gap will determine their optimum UV wavelength range to promote a photocatalytic process. There are different methods to assess the photocatalytic activity of a material. The most commonly used method is the degradation of a dye in aqueous solution under UV light, due to its simplicity. Under these conditions the decomposition rate of a suitable organic dye is used as a measure of activity. Physical properties such as particle size and surface area will determine the effective area that will interact and absorb the dye prior to degradation. The physical mechanisms involved in such aqueous based methods differ from gas phase reactions. More advanced techniques use mass spectrometers to evaluate photocatalytic activity of titanium dioxide in the gas phase. An effective photocatalyst for heterogeneous reactions in the gas phase is one which is efficient at creating radicals as a result of an absorbed photon.

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“…Recent developments in the application of electron ionisation mass spectrometry for the study of photo-catalytic activity have demonstrated the suitability and reliability of this approach for multiple pollutants. Studies have differentiated between rutile and anatase forms of TiO 2 under irradiation at different wavelengths in the UVA range [25].…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic activity of electrophoretically deposited (EPD) TiO2 coatings

et al. 2015

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This paper describes the application of electrophoretic deposition for air pollution removal using anatase as a photoactive coating. In this study, the anatase form of TiO 2 has been applied to (1) fluorine-doped tin oxide (FTO)-coated glass; (2) 304L stainless steel; and (3) titanium substrates using isopropanol and acetylacetonebased solutions at 20, 40, 60 and 80 V. In order to increase the strength of the substrate-anatase interface without transforming the phase into rutile, samples were calcined at 450°C for 2 h. The resulting coatings were characterised by Raman spectroscopy, X-ray diffraction, non-contact optical profilometry and scanning electron microscopy.The photocatalytic activity of the deposited coatings were evaluated in the gas phase for nitrogen dioxide (NO 2 ) removal by electron ionisation mass spectrometry, whilst irradiated by light of wavelength 376-387 nm for 100 min. Anatase phase titania supported on a FTO-coated glass substrate showed the highest photoactivity for NO 2 remediation. This was attributed to the formation of a threedimensional nanostructure with properties determined by the deposition conditions. This work provides routes for the development of low-cost and large area photoactive coatings for pollution control.

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Study of solid/gas phase photocatalytic reactions by electron ionization mass spectrometry

Cited by 12 publications

References 45 publications

Environmental performance of nano-structured Ca(OH)2/TiO2 photocatalytic coatings for buildings

Environmental performance of nano-structured Ca(OH)2/TiO2 photocatalytic coatings for buildings

Photocatalytic Properties of Commercially Available TiO2 Powders for Pollution Control

Photocatalytic activity of electrophoretically deposited (EPD) TiO2 coatings

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