Low energy photosynthesis of gold-titania catalysts

Kydd, Richard; Chiang, Kin Seng; Scott, Jason; Amal, Rose

doi:10.1039/b703528d

Cited by 22 publications

(12 citation statements)

References 28 publications

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“…In fact, according to the electron portioning effect involved in the conventional photodeposition process, gold NPs tend to nucleate and grow on the TiO 2 surface at oxygen-deficient titanium sites of high-electron density, which in the present case may correspond to the long living luminescent trap sites. Conversely, due to a different adsorption behavior of Pt ions and complexes from the solution onto the TiO 2 surface, the density of nucleation sites for Pt NPs may be dissimilar from those available for gold and therefore a greater level of dispersion is expected for Pt NPs in comparison to Au NPs for the same nominal metal loading. Indeed, the HR-TEM images reported in Figures and fully confirm that photodeposited Pt NPs are smaller in size and much better dispersed on the TiO 2 surface than Au NPs.…”

Section: Resultsmentioning

confidence: 85%

“…This might be a consequence of a different distribution of photodeposited Pt NPs on the oxide surface, with respect to photodeposited Au NPs, for which a specific interaction with the trap states introduced by doping appears to be favored due to a different mechanism governing the growth of Pt respect to Au NPs during the photodeposition step on the oxide material. In fact, according to the electron portioning effect involved in the conventional photodeposition process, gold NPs tend to nucleate and grow on the TiO 2 surface at oxygen-deficient titanium sites of high-electron density, which in the present case may correspond to the long living luminescent trap sites. Conversely, due to a different adsorption behavior of Pt ions and complexes from the solution onto the TiO 2 surface, the density of nucleation sites for Pt NPs may be dissimilar from those available for gold and therefore a greater level of dispersion is expected for Pt NPs in comparison to Au NPs for the same nominal metal loading.…”

Section: Resultsmentioning

confidence: 85%

“…If one considers the PL signal decrease recorded with NM NPs-modified doped or undoped materials (Figure 6), it seems that Au rather than Pt NPs appear to be able to efficiently capture electrons trapped at defect sites, possibly because of their close proximity due to their specific nucleation and growth during photodeposition. 43 In a different way, Pt NPs seem to be less prone to depopulate such electron trap states, probably because of their broader distribution on the TiO 2 surface.…”

Section: Photocatalytic Production Of H 2 By Photosteam Reforming Of ...mentioning

confidence: 99%

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Effects of Photodeposited Gold vs Platinum Nanoparticles on N,F-Doped TiO₂ Photoactivity: A Time-Resolved Photoluminescence Investigation

et al. 2018

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The time-resolved photoluminescence (PL) in the nanosecond time scale of TiO2 materials undoped or codoped with nitrogen and fluorine (N,F-doping) and modified by noble metals (NM, i.e. Au or Pt) nanoparticles (NPs) photodeposition has been systematically investigated in relation to their photocatalytic activity in hydrogen production. The main aim of the study is to elucidate the origin of the NM-dependent synergistic effects in photoactivity produced by N,F-doping of TiO2 and NM NPs deposition on the oxide surface. While TiO2 doping with fluorine and nitrogen introduces new stabilized luminescent defective trap states below the conduction band revealed by long-living PL components, the presence of NM NPs on the TiO2 surface produces a PL intensity suppression, which is more relevant for Au- rather than for Pt-NPs containing materials. Time-resolved PL analysis indicates that the electron transfer occurring at the TiO2/metal interface is affected by both the defective structure of anatase N,F-doped TiO2 and the type of NM (Au or Pt). In particular, Au rather than Pt NPs appear to strongly interact with the charge carriers trapped at surface defect sites, gold NPs being expected to preferentially grow on such sites during photodeposition. Furthermore, plasmonic gold NPs excitation upon PL light absorption is evidenced by the PL spectral shape variation observed only in the case of Au/TiO2. Thus, the larger synergistic effect on photocatalytic hydrogen production observed upon Au NPs photodeposition on N,F-doped TiO2 results from the opening of a new efficient electron transfer path from luminescent defective trap states on doped TiO2 to Au NPs, where proton reduction occurs.

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 85%

Section: Photocatalytic Production Of H 2 By Photosteam Reforming Of ...mentioning

confidence: 99%

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Effects of Photodeposited Gold vs Platinum Nanoparticles on N,F-Doped TiO₂ Photoactivity: A Time-Resolved Photoluminescence Investigation

et al. 2018

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“…Most of the methods published for the preparation of metal-decorated TiO 2 by photodeposition involve suspended particles in aqueous media [35][36][37][38][39][40][41][42][43][44][45], although non-aqueous methods have recently been reported [46,47]. Our approach for the scaleup process was different, and was developed based on sample preparation for metal photodeposition on microscope grids as discussed in the previous study [34].…”

Section: Introductionmentioning

confidence: 99%

Physico-Chemical Effects on the Scale-Up of Ag Photodeposition on TiO2 Nanoparticles

Chan

Barteau

2011

Top Catal

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We have previously demonstrated that TiO 2 nanoparticles can be functionalized by photodeposition with silver or gold particles in the 1-2 nm range presumed to be desirable for catalysis applications. However, the preparation of these samples directly on microscope grids, while conducive to particle size determinations, did not produce sufficient materials for reaction studies. We report here scale-up techniques designed to produce greater quantities of material for testing, while maintaining characteristics that contribute to uniformity in the deposition process. For the scale-up process, an irradiation source with highly uniform intensity is necessary to generate Ag/TiO 2 samples with consistent Ag loading. In addition, control of the precursor concentration is also required to produce Ag/ TiO 2 samples with high Ag loading and narrow Ag size distribution. The optimum conditions for the scale-up process found in this study involved Ag photodeposition from a 5 9 10 -3 M AgNO 3 solution using a high pressure Hg lamp at 366 nm for 60 s. Under these reaction conditions, the size of Ag particles determined by TEM and HAADF-STEM imaging was within 1-2 nm and the Ag loading was *3.2 wt%. Achievement of this level of uniformity required control of the uniformity of illumination, as well as of the solution concentration and irradiation conditions. Higher solution concentrations and higher power led to the growth of larger (ca. 10 nm) silver particles. In contrast, the loading and size distribution of the Ag particles photodeposited were remarkably insensitive to the source and morphology of the TiO 2 nanoparticles utilized. No Ag peak was resolved in the XRD patterns for Ag/TiO 2 samples obtained from the optimized scale-up process, corroborating the size range determination of the Ag nanoparticles. XPS showed that the Ag particles in all cases were metallic Ag.

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“…This synthetic approach does not require any additional templates and reduction agents, and thus offers not only an attractive possibility for the manufacture of thin film microcircuits and devices, but also could offer a very efficient and economic technique for the preparation of nanoparticles. Another example of the photosynthetical obtaining of metal nanoparticles is production of comparatively high-activity gold-titania catalysts supported on TiO 2 [110]. These materials were tested in the carbon monoxide oxidation reaction and returned markedly higher levels of activity at room temperature, when compared to catalysts prepared by the traditional photodeposition method.…”

Section: Methods For Metal Activation and Applications Of Obtained Acmentioning

confidence: 99%

Synthetic Techniques and Applications of Activated Nanostructurized Metals: Highlights up to 2008

Kharissova

Kharisov²

2008

NANOTEC

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Main methods for current production of metallic nanoparticles in different forms are reviewed. Metal nanoparticles are generally synthesized in form of nanopowders, nanowires, nanoclusters, nanorods, nanobelts, and nanofilms. Bi- and trimetallic clusters and alloys are also of an interest. Examined techniques for obtaining metal nanoparticles include chemical vapor and electrochemical deposition, use of gamma-, X-ray, laser and UV-irradiation, ultrasonic and microwave treatment, electron- and ion-beams, arc discharge, decomposition and reduction of metal salts and complexes, and biosynthesis. A special attention is paid to Rieke and supported metals.

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Low energy photosynthesis of gold-titania catalysts

Cited by 22 publications

References 28 publications

Effects of Photodeposited Gold vs Platinum Nanoparticles on N,F-Doped TiO₂ Photoactivity: A Time-Resolved Photoluminescence Investigation

Effects of Photodeposited Gold vs Platinum Nanoparticles on N,F-Doped TiO₂ Photoactivity: A Time-Resolved Photoluminescence Investigation

Physico-Chemical Effects on the Scale-Up of Ag Photodeposition on TiO2 Nanoparticles

Synthetic Techniques and Applications of Activated Nanostructurized Metals: Highlights up to 2008

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Low energy photosynthesis of gold-titania catalysts

Cited by 22 publications

References 28 publications

Effects of Photodeposited Gold vs Platinum Nanoparticles on N,F-Doped TiO2 Photoactivity: A Time-Resolved Photoluminescence Investigation

Effects of Photodeposited Gold vs Platinum Nanoparticles on N,F-Doped TiO2 Photoactivity: A Time-Resolved Photoluminescence Investigation

Physico-Chemical Effects on the Scale-Up of Ag Photodeposition on TiO2 Nanoparticles

Synthetic Techniques and Applications of Activated Nanostructurized Metals: Highlights up to 2008

Contact Info

Product

Resources

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Effects of Photodeposited Gold vs Platinum Nanoparticles on N,F-Doped TiO₂ Photoactivity: A Time-Resolved Photoluminescence Investigation

Effects of Photodeposited Gold vs Platinum Nanoparticles on N,F-Doped TiO₂ Photoactivity: A Time-Resolved Photoluminescence Investigation