IR spectroscopy as a tool to investigate photocatalytic reactions at oxide surfaces

Mino, Lorenzo

doi:10.1007/s12210-016-0592-9

Cited by 10 publications

(7 citation statements)

References 23 publications

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“…Infrared spectroscopy has been widely used to study the interactions of methanol and water with the TiO2 surface [6][7][8][9][10] and to provide information on the photoreaction mechanism [10][11][12][13][14][15]. In addition to the detection of surface species formed during the photoreaction, time resolved FT-IR spectroscopy proved to be a powerful tool to distinguish between photopromoted free CB electrons and shallow trapped (ST) electrons and to evaluate their lifetime [8,[16][17][18].…”

Section: Introductionmentioning

confidence: 99%

In situ attenuated total reflection infrared spectroscopy study of the photocatalytic steam reforming of methanol on Pt/TiO2

Chiarello

Ferri

Selli

2018

Applied Surface Science

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The effect of Pt deposition on TiO2 and of Pt particle size on the photocatalytic steam reforming of methanol was studied by in-situ attenuated total reflectance infrared spectroscopy (ATR-IR). Two 0.5 wt.% Pt/TiO2 samples were investigated, one possessing Pt nanoparticles of ca. 4 nm mean size, the other Pt clusters of ca. 1.3 nm mean size showing significantly different photoactivity in terms of both hydrogen production rate and selectivity to CO, CO2 and all other by-products. The presence of Pt nanoparticles strongly affects both the adsorption/desorption and the reactivity properties of the TiO2 surface. Moreover, the variation of the IR spectrum background upon UV-vis irradiation proved that the photopromoted electrons can be trapped by the Pt particles with the consequent increasing of electron-hole separation. Reducing the Pt size from nanoparticles to clusters increases the rate of methanol and water absorption and hinders the detrimental formation of irreversibly adsorbed CO on Pt. All of these aspects contribute to increase the photocatalytic performance of Pt cluster-decorated TiO2 with respect to Pt nanoparticles containing TiO2. Finally, prolonged exposure of all samples to methanol/water vapour in the dark led to the formation of unreactive formate which persists also under UV-vis irradiation. By contrast, this spectator species does not form when the sample is exposed to methanol/water vapour under UV-vis irradiation.

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Section: Introductionmentioning

confidence: 99%

In situ attenuated total reflection infrared spectroscopy study of the photocatalytic steam reforming of methanol on Pt/TiO2

Chiarello

Ferri

Selli

2018

Applied Surface Science

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“…In this context, our group investigated several TiO 2 anatase and rutile samples using IR spectroscopy to study the surface properties and the processes occurring at the oxide surface during photocatalytic reactions. [55] For instance, the use of adsorbed carbon monoxide as molecular probe [25d,56] allowed us to obtain information at molecular level on the different exposed surfaces. Indeed, in the IR spectra, obtained for the adsorption of CO at 60 K on a TiO 2 sample (Figure 3a), several signals can be observed, and most of these spectral features are related to the internal stretching mode of CO interacting with the Ti 4 + surface sites.…”

Section: Shape Engineering Of Tio 2 Nanoparticlesmentioning

confidence: 99%

Ti‐Based Catalysts and Photocatalysts: Characterization and Modeling

Mino

Signorile

Crocellà

et al. 2018

The Chemical Record

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This perspective article aims to underline how cutting‐edge synchrotron radiation spectroscopies such as extended X‐ray absorption spectroscopy (EXAFS), X‐ray absorption near edge structure (XANES), high resolution fluorescence detected (HRFD) XANES, X‐ray emission spectroscopy (XES) and resonant inelastic X‐ray scattering (RIXS) have played a key role in the structural and electronic characterization of Ti‐based catalysts and photocatalysts, representing an important additional value to the outcomes of conventional laboratory spectroscopies (UV‐Vis, IR, Raman, EPR, NMR etc.). Selected examples are taken from the authors research activity in the last two decades, covering both band‐gap and shape engineered TiO2 materials and microporous titanosilicates (ETS‐10, TS‐1 and Ti−AlPO‐5). The relevance of the state of the art simulation techniques as a support for experiments interpretation is underlined for all the reported examples.

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“…Interestingly, during the photoreduction process CO adsorbs on the reduced Mo sites forming carbonyls whose spectroscopic properties in the mid-IR region depend on the metal oxidation and coordination state. Therefore, the spectroscopic study of the adsorbed molecules represents a useful way to probe the nature of the different surface species that are progressively formed [ 19 , 20 , 21 ]. Many researchers have investigated these carbonyl species, giving sometimes contradictory interpretations of the spectroscopic data.…”

Section: Introductionmentioning

confidence: 99%

Probing Molybdenum Active Sites during In Situ Photoreduction of the Mo6+/SiO2 Catalyst

2021

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The photoreduction of the Mo6+/SiO2 system with CO was investigated in situ, employing a recently developed experimental setup allowing for the acquisition of transmission FT-IR spectra under simultaneous UV irradiation. Carbon monoxide, besides acting as a reducing agent in such processes, is also a useful probe molecule able to detect coordinatively unsaturated sites exposed on the surface. The unprecedented quality of the spectroscopic data, obtained as a function of the reduction time, allowed us to better rationalize the different mechanisms previously proposed for the photoreduction process. These results, coupled with UV-Vis spectroscopic data, shed light on the oxidation state and surface structure of supported molybdenum species, which are key active sites for several important reactions, such as selective oxidation, polymerization, hydrodesulfurization, epoxidation and olefin metathesis.

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IR spectroscopy as a tool to investigate photocatalytic reactions at oxide surfaces

Cited by 10 publications

References 23 publications

In situ attenuated total reflection infrared spectroscopy study of the photocatalytic steam reforming of methanol on Pt/TiO2

In situ attenuated total reflection infrared spectroscopy study of the photocatalytic steam reforming of methanol on Pt/TiO2

Ti‐Based Catalysts and Photocatalysts: Characterization and Modeling

Probing Molybdenum Active Sites during In Situ Photoreduction of the Mo6+/SiO2 Catalyst

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