Amorphous–anatase phase transition in single immobilized TiO2 nanoparticles

Khatim, O.; Amamra, M.; Chhor, K.; Bell, Anthony M. T.; Новиков, Д. В.; Vrel, D.; Kanaev, Andreï

doi:10.1016/j.cplett.2012.12.019

Cited by 45 publications

(36 citation statements)

References 24 publications

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“…A broad band at 700 cm −1 intensifies strongly after heat treatments beyond 300 °C and is split up into multiple bands after 400 °C (Figure S18 in the Supporting Information) . It has been suggested that the phase transition temperature of amorphous TiO 2 to anatase is around 400 °C, but this shifts to around 500 °C when heating amorphous NPs . Beyond 300 °C, the TiO 2 coating starts to densify and crystallize and at around 500 °C it definitely cracks open, which allows the Au cores to sinter.…”

Section: Resultsmentioning

confidence: 99%

Thermally Stable TiO₂‐ and SiO₂‐Shell‐Isolated Au Nanoparticles for In Situ Plasmon‐Enhanced Raman Spectroscopy of Hydrogenation Catalysts

Hartman

Weckhuysen

2018

Chemistry A European J

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Raman spectroscopy is known as a powerful technique for solid catalyst characterization as it provides vibrational fingerprints of (metal) oxides, reactants, and products. It can even become a strong surface‐sensitive technique by implementing shell‐isolated surface‐enhanced Raman spectroscopy (SHINERS). Au@TiO2 and Au@SiO2 shell‐isolated nanoparticles (SHINs) of various sizes were therefore prepared for the purpose of studying heterogeneous catalysis and the effect of metal oxide coating. Both SiO2‐ and TiO2‐SHINs are effective SHINERS substrates and thermally stable up to 400 °C. Nano‐sized Ru and Rh hydrogenation catalysts were assembled over the SHINs by wet impregnation of aqueous RuCl3 and RhCl3. The substrates were implemented to study CO adsorption and hydrogenation under in situ conditions at various temperatures to illustrate the differences between catalysts and shell materials with SHINERS. This work demonstrates the potential of SHINS for in situ characterization studies in a wide range of catalytic reactions.

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Section: Resultsmentioning

confidence: 99%

Thermally Stable TiO₂‐ and SiO₂‐Shell‐Isolated Au Nanoparticles for In Situ Plasmon‐Enhanced Raman Spectroscopy of Hydrogenation Catalysts

Hartman

Weckhuysen

2018

Chemistry A European J

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“…The largest pore shrinkage is expected to occur for the sample, prepared using PEG with highest molecular mass (TiO 2 /P10000), which would result in production of amorphous TiO 2 with denser particles package and reduced porosity. As a consequence of denser amorphous network, the orientation and frequency of anatase twin nucleation would be higher [42], leading to more rapid progression of anatase to rutile transformation [40,43].…”

Section: Catalysts Characterizationmentioning

confidence: 99%

Structure–activity relationship of nanosized porous PEG-modified TiO2 powders in degradation of organic pollutants

Lončarević

Dostanić

Radonjić

et al. 2015

Advanced Powder Technology

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“…Ultraporous aluminas (UPA) 1, 2 attract considerable interest because of their potential applications in catalysis, filtration, optoelectronics, photonics, etc. They serve as excellent supporting matrixes for active components in the form of monolayer molecules and single nanoparticles 3–5. Because of an exceptionally low impurity concentration, these materials do not contaminate supported nanoparticles during thermal treatment up to 1000 °C.…”

Section: Introductionmentioning

confidence: 99%

Governing Chemistry of Cellulose Hydrolysis in Supercritical Water

2015

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9This article summarizes the recent efforts in the High Pressure Processes Group labs at UVa 10 regarding the fundamentals of biomass hydrolysis in pressurized water medium. At extremely 11 low reaction times (0.02 s), cellulose was hydrolyzed in supercritical water (400ºC and 25 12 MPa) obtaining a sugars yield higher than 95% w·w -1 while 5-HMF yield was lower than 13 0.01% w·w -1 . When the reaction times was increased up to 1 s, the main product was 14 glycolaldehyde (60% w·w -1 ). Independently of the reaction time, the yield of 5-HMF was 15 always lower than 0.01% w·w -1 . In order to evaluate the reaction pathway and mechanism of 16 plant biomass in pressurized water, several parameters (temperature, pressure, reaction time 17 and reaction medium) were studied for different biomasses (cellulose, glucose, fructose and 18 wheat bran). It was considered that the reactions of glucose isomerization to fructose as well 19 as fructose dehydration to 5-HMF take place via proton or hydroxide anion association. So, 20 their concentration was taken into account as reagent concentration in the reaction 21 evaluations. It was found that the proton and hydroxide anion concentration in the medium 22 due water dissociation is the determining factor in the selectivity of the process. The reaction 23 of glucose isomerization to fructose and its further dehydration to produce 5-HMF are highly 24 dependent on ions concentration. By increasing pOH/pH, these reactions were minimized 25 allowing the control of 5-HMF production. At this condition, the retro-aldol condensation 26 pathway was enhanced instead of isomerization/dehydration pathway. 27 3 INTRODUCTION 28

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Amorphous–anatase phase transition in single immobilized TiO2 nanoparticles

Cited by 45 publications

References 24 publications

Thermally Stable TiO₂‐ and SiO₂‐Shell‐Isolated Au Nanoparticles for In Situ Plasmon‐Enhanced Raman Spectroscopy of Hydrogenation Catalysts

Thermally Stable TiO₂‐ and SiO₂‐Shell‐Isolated Au Nanoparticles for In Situ Plasmon‐Enhanced Raman Spectroscopy of Hydrogenation Catalysts

Structure–activity relationship of nanosized porous PEG-modified TiO2 powders in degradation of organic pollutants

Governing Chemistry of Cellulose Hydrolysis in Supercritical Water

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Amorphous–anatase phase transition in single immobilized TiO2 nanoparticles

Cited by 45 publications

References 24 publications

Thermally Stable TiO2‐ and SiO2‐Shell‐Isolated Au Nanoparticles for In Situ Plasmon‐Enhanced Raman Spectroscopy of Hydrogenation Catalysts

Thermally Stable TiO2‐ and SiO2‐Shell‐Isolated Au Nanoparticles for In Situ Plasmon‐Enhanced Raman Spectroscopy of Hydrogenation Catalysts

Structure–activity relationship of nanosized porous PEG-modified TiO2 powders in degradation of organic pollutants

Governing Chemistry of Cellulose Hydrolysis in Supercritical Water

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Thermally Stable TiO₂‐ and SiO₂‐Shell‐Isolated Au Nanoparticles for In Situ Plasmon‐Enhanced Raman Spectroscopy of Hydrogenation Catalysts

Thermally Stable TiO₂‐ and SiO₂‐Shell‐Isolated Au Nanoparticles for In Situ Plasmon‐Enhanced Raman Spectroscopy of Hydrogenation Catalysts