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[Display omitted] • Production of Hierarchical TiO 2 structures (nanoribbons/spherulites) with a single crystalline rutile phase. • The use of glycerol oxidation as a hole scavenger made it possible to reach 1.54 mAcm−2 (V vs. RHE, 83% of theoretical J abs). • PEC hydrogen generation of 2.2 mL H 2 cm−2h−1 under 1 Sun (AM 1.5G filter, 100 mWcm−2), representing 51 % faradaic efficiency. • The developed photoanodes achieved 0.81% applied bias photon-to-current efficiency (ABPE), and. • The photoanodes demonstrated stability in long-term operation, sustaining performance for 12 h. In this work, we present the use of hydrothermal strategies to produce hierarchical TiO 2 structures (nanoribbons/spherulites) with a rutile single crystalline phase. Using the hydrothermal synthesis, controlling the concentration of Cl- and Sn4+, a high-efficiency system with a rutile crystalline phase was obtained. Using glycerol as a hole-scavenger, promoting the photo(electro)reforming, the prepared photoanodes obtained photocurrent densities of 1.54 mA cm−2 (at 1.23 V vs. RHE) with 0.81 % of applied bias photon-to-current efficiency (ABPE) and photoelectrochemical hydrogen generation of 2.2 mL H 2 cm-2h−1, under 1 Sun (AM 1.5G filter, 100 mW cm−2) and longtime stability. [ABSTRACT FROM AUTHOR]

Abstract We examine comparatively the performance of sputtered TiO2 rutile and anatase thin films as an electron transport layer (ETL) in MAPbI3‐based perovskite solar cells. Both anatase and rutile TiO2 ETLs are deposited (on fluorine‐doped tin oxide [FTO] substrates) by magnetron sputtering in the form of nanocrystalline thin films. We systematically investigate the role of crystallographic phase composition of TiO2 ETLs on the photovoltaic performance of perovskite solar cells. The champion power conversion efficiencies (PCEs) of 18.4% and 17.7% under reverse scan mode are obtained for perovskite solar cells based on TiO2 anatase and TiO2 rutile ETL, respectively. The results show that the magnetron sputtering deposited ETLs differ from each other only in their phase composition while the overall performance of the devices is not greatly affected by the crystallographic phase of the TiO2 ETLs. Our results point to an important fact that for a proper and reliable comparison between the performance of TiO2 anatase and rutile ETLs, it is crucial to investigate films of similar morphology and structure that are synthesize under similar conditions.

The decomposition of ethanol, one of the most important biomass platform molecules, was investigated under green conditions, ambient temperature, atmospheric pressure and air for the synthesis of acetal in the presence of TiO2 activated under UV-A radiation. The impact of ethanol concentration, of the nature of TiO2 (rutile, anatase or mixture), of the photo-deposition of Pt under air or argon were all factors under investigation. Whatever the conditions and the nature of catalyst used, acetaldehyde was initially formed before reacting with ethanol to form acetal, a promising fuel additive. However, the subsequent generation of acetal differs depending on the conditions and the nature of catalyst. In the absence of a noble metal, rutile TiO2 leads to an increase in acetal formation at equivalent acetaldehyde formation. This behavior is discussed considering the acidic and basic properties of rutile and anatase phases together with H+ generated under UV. In the presence of Pt, under air or Ar, the acetal formation begins at a lower concentration of acetaldehyde due to the in-situ photo-deposition of Pt. However, whereas acetal formation is similar for Pt/anatase and Pt/rutile phase under air, under Ar, less acetal is generated on Pt/rutile in agreement with the production of more H2. [ABSTRACT FROM AUTHOR]

We examine comparatively the performance of sputtered TiO2 rutile and anatase thin films as an electron transport layer (ETL) in MAPbI3‐based perovskite solar cells. Both anatase and rutile TiO2 ETLs are deposited (on fluorine‐doped tin oxide [FTO] substrates) by magnetron sputtering in the form of nanocrystalline thin films. We systematically investigate the role of crystallographic phase composition of TiO2 ETLs on the photovoltaic performance of perovskite solar cells. The champion power conversion efficiencies (PCEs) of 18.4% and 17.7% under reverse scan mode are obtained for perovskite solar cells based on TiO2 anatase and TiO2 rutile ETL, respectively. The results show that the magnetron sputtering deposited ETLs differ from each other only in their phase composition while the overall performance of the devices is not greatly affected by the crystallographic phase of the TiO2 ETLs. Our results point to an important fact that for a proper and reliable comparison between the performance of TiO2 anatase and rutile ETLs, it is crucial to investigate films of similar morphology and structure that are synthesize under similar conditions. [ABSTRACT FROM AUTHOR]

Photodegradation of 1,2-dichlorobenzene over illuminated trimetallic oxide consisting of rutile TiO2 in major portion together with WO3 and SnO2 was studied with respect to the effect of physicochemical properties of the catalyst. The photocatalytic activity enhancement by the presence of surface defects due to calcination temperature was investigated with the information obtained from XRD, DRUV, PL, FESEM and XPS. Calcination of TiO2 at 950 °C resulted in highest activity. Decrease in percentage of degradation of 1,2-dichlorobenzene was noted when it was immobilized on PVC film and chitosan beads. The effect of calcination temperature, catalyst loading and pH was investigated for slurry and after immobilization. Further optimization study was carried out with the aid of response surface methodology utilizing Box–Behnken design. High correlation was obtained for the experimental and the predicted value (R2 = 0.9992, Adj. R2 = 0.9982 and Pred. R2 = 0.9971). Optimization result showed that the maximum percentage of degradation was achieved at calcination temperature of 961.2 °C, with catalyst loading of 0.22 g and pH 7.2. The presence of two intermediates was identified during the reaction using GC–MS. On top of that the photocatalyst could also be reused for several times.

In this study, a dual-phase Li4Ti5O12-TiO2 microrod was successfully prepared using a modified hydrothermal method and calcination process. The stoichiometry of LiOH as precursor was varied at mol ratio of 0.9, 1.1, and 1.3, to obtain the appropriate phase composition between TiO2 and Li4Ti5O12. Results show that TiO2 content has an important role in increasing the specific capacity of electrodes. The refinement of X-ray diffraction patterns by Rietveld analysis confirm that increasing the LiOH stoichiometry suppresses the TiO2 phase. In the scanning electron microscopy images, the microrod morphology was formed after calcination with diameter sizes ranging from 142.34 to 260.62 nm and microrod lengths ranging from 5.03–7.37 μm. The 0.9 LiOH sample shows a prominent electrochemical performance with the largest specific capacity of 162.72 mAh/g and 98.75% retention capacity achieved at a rate capability test of 1 C. This finding can be attributed to the appropriate amount of TiO2 that induced the smaller crystallite size, and lower charge transfer resistance, enhancing the lithium-ion insertion/extraction process and faster diffusion kinetics.

Photodegradation of 1,2-dichlorobenzene over illuminated trimetallic oxide consisting of rutile TiO2 in major portion together with WO3 and SnO2 was studied with respect to the effect of physicochemical properties of the catalyst. The photocatalytic activity enhancement by the presence of surface defects due to calcination temperature was investigated with the information obtained from XRD, DRUV, PL, FESEM and XPS. Calcination of TiO2 at 950 °C resulted in highest activity. Decrease in percentage of degradation of 1,2-dichlorobenzene was noted when it was immobilized on PVC film and chitosan beads. The effect of calcination temperature, catalyst loading and pH was investigated for slurry and after immobilization. Further optimization study was carried out with the aid of response surface methodology utilizing Box-Behnken design. High correlation was obtained for the experimental and the predicted value (R2 = 0.9992, Adj. R2 = 0.9982 and Pred. R2 = 0.9971). Optimization result showed that the maximum percentage of degradation was achieved at calcination temperature of 961.2 °C, with catalyst loading of 0.22 g and pH 7.2. The presence of two intermediates was identified during the reaction using GC-MS. On top of that the photocatalyst could also be reused for several times. [ABSTRACT FROM AUTHOR]

Following our strategy to analyze the metal–support interaction, we present periodic DFT calculations for adsorption of metal atoms on a perfect rutile TiO2(110) surface (at low coverage, θ = 1/3) to investigate the interaction of an individual metal atom, M, with TiO2 and its consequence on the coadsorption of H and CO over M/TiO2. M under investigation varies in a systematic way from K to Zn. It is found that the presence of the support decreases or increases the strength of M–H or M–CO interaction according to the nature of M. The site of the adsorption for H and the formation of HCO/M also depend on M. From the left- to the right-hand side of the period, C and O both interact while O progressively detaches from M. On the contrary, for M = Fe–Cu, CO dissociation is more likely to happen. For CO and H coadsorption, two extreme cases emerge: For Ni, the hydrogen adsorbed should easily move on the support and CO dissociation is more likely. For Ti or Sc, H is easily coadsorbed with CO on the metal and CO hydrogenation could be the initial step. [ABSTRACT FROM AUTHOR]

The aim of this work was to clarify the effect of the support on CO selective methanation with Ru/TiO 2 catalysts. TPR, XRD and TEM measurements confirmed that the changes in the activity and selectivity should be ascribed to anatase:rutile ratio, RuO 2 +TiO 2 solid solution formation, as well as the metal content and the thermal treatment used. All these characteristics result in active and selective catalysts in which the suppression of the reverse water gas shift reaction was observed. The catalytic performance must be explained by both the formation of more active Ru species as a result of support influence and the higher Ru dispersion. The study allows to conclude that for CO activation the role of support surface hydroxyls seems to be determinant for both the activity and selectivity of Ru/TiO 2 catalysts. [Display omitted] • Selective Ru/TiO2 catalysts for CO methanation were prepared. • Role of support surface hydroxyls seems to be determinant. • Formation of more active Ru species thanks to TiO2-P25. • Anatase → rutile transformation and RuO2 +TiO2 species promote the activity. [ABSTRACT FROM AUTHOR]

The effect of coated rutile titanium dioxide (T1O2) and a disazopyrazolone dye (azo dye) on the mechanism and the kinetic of photo-oxidation of unvulcanized styrene butadiene rubber (SBR) composites under accelerated UV-visible irradiation (λ > 290 nm at 35 °C) has been investigated using several techniques such as infrared spectroscopy, UV-visible spectrophotometry, and gel fraction measurements. Different photo-products resulting from the photo-ageing such as alcohol, ketone, or acids as well as cross-linked network were identified. The incorporation of T1O2 rutile and an azo dye into the matrix did not modify the mechanism of photo-oxidation. However, they have a significant effect on the kinetic of photoproducts accumulation. Both fillers protect the matrix from photo-oxidation. TiO2 rutile, thanks to its inorganic coating at the surface, dissipates part of the UV-visible radiation received by the polymer. The activity mechanism of azo dye consisting of a combination of its function as an antioxidant and light absorber, presents a better stabilizing effect compared with TiO2 rutile. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the properties of nanosized TiO2 rutile by electrochemical methods and thermal analysis. The material shows a high capacity, high rate performance and excellent cycling stability. We can clearly prove the safer character of rutile electrodes by thermal analysis. The lithiated rutile electrodes exhibit exothermic reactions with a very small energy release and they are mainly related to surface film (SEI) decomposition. The impedance spectra strongly indicate the formation of a surface film, but the semicircles of charge transfer and SEI formation cannot be resolved at any potential. In addition a new pouch cell design which is suitable for in situ measurements such as FTIR, Raman and XRD is introduced and its efficiency is proven by in situ optical microscopy. [Copyright &y& Elsevier]

Abstract: Photoetching is known to compete with water photooxidation at n-TiO2 rutile electrodes in contact with aqueous H2SO4 solutions under UV illumination and anodic bias. A mechanism based on the generation of bridging hydroxyl species from the adsorption of water molecules at photoinduced bridging oxygen vacancies is proposed in order to explain the competition between both photoreactions. This mechanism, designated as Redox Photooxidation (RP) Mechanism, correlates the atomic arrangement of the TiO2 surface with its photocatalytic activity, considering that the first step for water photooxidation is the photogeneration of bridging oxygen/hydroxyl radicals associated with intrinsic bandgap surface states, via inelastic transfer of free valence band holes to bridging oxygen/hydroxyl groups, depending on the electrolyte pH. The critical distance between adjacent bridging oxygen/hydroxyl radicals allows their covalent bonding with generation of surface-bound peroxide species, which are further photooxidized leading to oxygen evolution. The RP mechanism allows to explain literature experimental results concerning surface modifications of n-TiO2 rutile during photoetching in competition with water photooxidation, as well as their dependence on crystal orientation. The photogeneration of chemisorbed peroxo species, intermediates of the oxygen evolution reaction, detected by MIRIR spectroscopy, as well as experimental results obtained from PL and DEMS experiments are also interpreted in the light of the RP mechanism. A comparative analysis with the nucleophilic attack (NA) Mechanism, an alternative model proposed recently to explain photoelectrochemical water oxidation at n-TiO2 rutile, is presented. [Copyright &y& Elsevier]

Abstract: The TiO2 rutile thin films were grown on Si(100) substrates with ZnO buffer layer at a substrate temperature of 500 °C by radio frequency (rf) magnetron sputtering. In order to investigate the effect of buffer layer thickness on the growth of the TiO2 film, the ZnO buffer layers were deposited in the thickness range of 70–150 nm. The thickness of the TiO2 films was about 200 nm identical for all the samples. The crystal structure of the buffer layers and the TiO2 thin films was characterized by X-ray diffractometer (XRD). The XRD spectra confirmed that TiO2 rutile film with high crystalline quality was achieved on the ZnO buffer layer, which had a great relation to the improvement of the crystalline quality of the ZnO buffer layer. The surface morphologies of the TiO2 rutile thin films were evaluated by atomic force microscopy (AFM). The roughness of the TiO2 thin films became smoother as the thickness of the ZnO buffer layer increased. [Copyright &y& Elsevier]

Abstract: A series of TiO2 supported manganese oxide catalysts were prepared by wet-impregnation method for the low temperature selective catalytic reduction (SCR) of NO with ammonia as a reductant. A combination of various physico-chemical techniques such as N2 physisorption, O2 chemisorption, TPR, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman were used to characterize the chemical environment of these catalysts. O2 chemisorption and XRD results suggest that Mn exist in a well-dispersed state at below 16.7wt.% of Mn on TiO2 anatase (Hombikat), 7.5wt.% on TiO2 rutile (Kemira) and P-25 (80% anatase+20% rutile), and in microcrystalline phase above these loading levels on respective support materials. These results also reveal that Mn interacts very well with pure anatase phase compared to rutile. XPS results of Mn/TiO2 anatase (Hombikat) catalysts illustrated the presence of MnO2 as a major phase (peak at 642.0eV) along with Mn2O3 as the minor phase at lower loadings. The presence of Mn2O3 disappears at higher loadings. The characterization results indicated that the manganese oxide exists as an isolated species at very low loadings, highly dispersed state probably as two dimensional monolayer species at intermediate loadings, polymeric or microcrystalline form of manganese oxide at higher (above monolayer capacity) loadings was envisaged. The catalytic performance of various amounts of Mn loaded on different TiO2 supported catalysts for low temperature SCR reaction at catalyst bed temperature 175°C under power plant conditions using GHSV=50,000h−1 was studied. The catalyst with 16.7wt.% Mn/TiO2 anatase (Hombikat) was found to be highly active and selective catalyst for this reaction. The Raman studies acted as complimentary tool to XPS in order to characterize the manganese oxides (MnO, Mn2O3, Mn3O4, MnO2). Raman data show that there is a strong interaction between the Mn oxides and the support, which is responsible for the impressive catalytic performance in comparison with other systems we investigated. [Copyright &y& Elsevier]

Abstract: Photooxidation and photoreduction reaction rates on nanoparticulate TiO2 have been studied using a series of silica coated samples prepared from the same parent material—a high area rutile. Oxidation of propan-2-ol was measured by GC analysis of acetone product. Reduction of DPPH (1,1-diphenyl-2-picrylhydrazyl radical) was followed by the decrease in absorbance at 520nm and photogreying of TiO2 was measured as a change in L, the reflectance of the CIE Y illuminant centred at 550nm, using a Minolta chroma meter. The activity for oxidation of propan-2-ol correlated well with two measures of photoreduction, the reduction of the stable DPPH and TiO2 photogreying in an oxygen free system. In all cases, low silica loadings resulted in a small increase in activity. For silica levels >1wt.% the dependence of activity decreased with increasing levels of silica treatment. The pattern of activity versus silica-level was consistent with elimination of both photooxidation and photoreduction at 12–16% silica. A speculative interpretation of these changes was based on changes in the silica environment as determined by magic angle spinning NMR. [Copyright &y& Elsevier]

Abstract: The dose dependence of magnetism in Co-implanted TiO2 rutile was investigated using the magneto-optic Kerr effect method at room temperature. The (100)- and (001)-oriented single-crystalline rutile TiO2 plates were used as substrates and implanted by Co ions with a varying dose range of 0.25–1.50×1017 ions/cm2. We observed paramagnetic behaviour for the low dose doped samples, but obtain clear hysteretic-like behaviour for intermediate and high dose doped samples. For the intermediate implantation doses of Co, ferromagnetic behaviour can be explained by the F-center (oxygen vacancies) exchange mechanism, while for the highest implantation dose, in addition to Co substitution on Ti sites, formation of Co nanoclusters may take place within the TiO2 irradiated region. [Copyright &y& Elsevier]

In this study, a dual-phase Li4Ti5O12-TiO2 microrod was successfully prepared using a modified hydrothermal method and calcination process. The stoichiometry of LiOH as precursor was varied at mol ratio of 0.9, 1.1, and 1.3, to obtain the appropriate phase composition between TiO2 and Li4Ti5O12. Results show that TiO2 content has an important role in increasing the specific capacity of electrodes. The refinement of X-ray diffraction patterns by Rietveld analysis confirm that increasing the LiOH stoichiometry suppresses the TiO2 phase. In the scanning electron microscopy images, the microrod morphology was formed after calcination with diameter sizes ranging from 142.34 to 260.62 nm and microrod lengths ranging from 5.03–7.37 μm. The 0.9 LiOH sample shows a prominent electrochemical performance with the largest specific capacity of 162.72 mAh/g and 98.75% retention capacity achieved at a rate capability test of 1 C. This finding can be attributed to the appropriate amount of TiO2 that induced the smaller crystallite size, and lower charge transfer resistance, enhancing the lithium-ion insertion/extraction process and faster diffusion kinetics. [ABSTRACT FROM AUTHOR]