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Anatase TiO sub(2) nanoplates, with average side length ranging from 90 to 200 nm and average thickness ranging from 20 to 60 nm, were successfully fabricated by annealing anodized TiO sub(2) nanotubes with different heating rates. The as-synthesized TiO sub(2) nanoplates and nanotubes were analyzed by field-emission scanning electron microscopy, X-ray diffraction, X-ray fluorescence spectroscopy, and transmission electron microscopy. To investigate the growth mechanism of the TiO sub(2) nanoplates dominated by highly reactive {001} facets, different heating rates were applied appropriately during the thermal treatment. The results revealed that the heating rate during thermal treatment is critical in determining the nanostructure of anatase TiO sub(2). The fast heating rate (samples were annealed when the temperature heated up to 450 degree C) and the brittle property are the main reasons for the collapse of the anodized TiO sub(2) nanotubes. The nanosized TiO sub(2) species grow into TiO sub(2) nanoplates with the exposed 60 % of {001} facets because the fluorated surface of TiO sub(2) species can direct the formation of TiO sub(2) nanoplates with exposed {001} facets. The photoactivity of the TiO sub(2) nanoplates is higher than that of TiO sub(2) nanotubes.

The microstructure design of TiO sub(2) nanoparticles for photoanodes is an important issue in optimization of dye-sensitized solar cell (DSSC) performance. Up to date, the nanostructured TiO sub(2) particles have been extensively employed as active layers. However, less attention has been focused on the development of various TiO sub(2) nanostructures as the light-scattering layers (LSLs). In the present work, a facile hydrothermal method was utilized to prepare quasi-cube TiO sub(2) (qcTiO sub(2)) nanoparticles as the LSL for the DSSC photoanode. The anatase qcTiO sub(2) nanoparticles had a size distribution of 30-60 nm. The photoconversion efficiency of the cell with the qcTiO sub(2) LSL was enhanced 12 %, compared to the TiO sub(2) film without a scattering layer. The above enhancement was further vindicated by the incident photon-to-current efficiency measurement. The effect of the qcTiO sub(2) LSL on electron transport and charge recombination of the DSSC was studied by electrochemical impedance spectroscopy. The experiment results revealed that the enhanced photovoltaic performance is attributed to the better light-harvesting capacity, longer electron life time, and less charge recombination of the qcTiO sub(2) nanoparticles.

The preparation procedure of silicaatitania composite oxide using novel solution/sol single precursor containing titanium peroxocomplex and silicic acid has been described. Pechini-type sol-gel process has been used to prepare oxides from the aqueous precursor. Some structural, morphological and textural characteristics of the prepared material have been presented. Composite SiO2/TiO2 has high surface area (c.a. 300 m2/g), and it is composed of anatase nanoparticles with the mean diameter of 5 nm embedded in amorphous silica, then TiO2 prepared via similar method is presented as a mixture of anatase and rutile phases. The proposed synthetic procedure meets the requirements of agreen chemistrya.

There are two methods to estimate the particle size from X-ray diffraction data: the Debye equation and the Scherrer formula. The main goal of this study is to describe the methodology of particle size estimation on the base of two these methods and to apply it to TiO2 powder to determine the diameters and the mass content of anatase and brookite components. The studied nano-dispersed TiO2 powder was synthesized by the sol-gel method. The proposed method of particle size estimation consists of several steps: 1. Approximation of diffraction peaks by Gaussians and calculation of initial values of particle size with the use of the Scherrer formula; 2. Iterations with the use of the Debye equation to obtain more accurate particle size values; 3. Calculation of the mass content of different components corresponding to the minimum R-factor.

Understanding the adsorption and reactivity of carboxylic acids on oxide surfaces is of great interest in catalysis for biomass upgrading via ketonization, a carbon–carbon coupling reaction. Herein, we investigate the adsorption and reaction of acetic acid on anatase TiO 2 (101) using scanning tunneling microscopy, infrared spectroscopy, temperature programmed reaction, and density functional theory calculations. We demonstrate the adsorption of acetic acid can form two intermediates: (1) dissociated, bidentate acetate with an associated bridging hydroxyl, and (2) molecular, monodentate acetic acid. The coexistence of ordered phases with increasing monolayer (ML) saturation coverages consisting of (1) pure acetate (0.5 ML), (2) mixed acetate/acetic acid (0.67 ML), (3) mixed acetate/acetic acid (1.0 ML) and (4) pure acetic acid demonstrates similar energetics for both acetate and acetic acid species. Under ultra-high vacuum conditions, the presence of both monodentate acetic acid and bidentate acetate was observed below room temperature, while solely bidentate acetate was observed up to 575 K. The deprotonation of acetic acid produces water at 280 K, while the thermal decomposition of bidentate acetate produces ketene and acetic acid at 645 K. This model study provides detailed insight into the stability and reactivity of carboxylic acid surface-bound intermediates, which could participate during ketonization reactions for biomass upgrading.

Supports can widely affect or even dominate the catalytic activity, selectivity, and stability of metal nanoparticles through various metal-support interactions (MSIs). However, underlying principles have not been fully understood yet, because MSIs are influenced by the composition, size, and facet of both metals and supports. Using Ru/TiO 2 supported on rutile and anatase as model catalysts, we demonstrate that metal-support interfacial compatibility can critically control MSI modes and catalytic performances in CO 2 hydrogenation. Annealing Ru/rutile-TiO 2 in air can enhance CO 2 conversion to methane resulting from enhanced interfacial coupling driven by matched lattices of RuO x with rutile-TiO 2 ; annealing Ru/anatase-TiO 2 in air decreases CO 2 conversion and converts the product into CO owing to strong metal-support interaction (SMSI). Although rutile and anatase share the same chemical composition, we show that interfacial compatibility can basically modify metal-support coupling strength, catalyst morphology, surface atomic configuration, MSI mode, and catalytic performances of Ru/TiO 2 in heterogeneous catalysis. Supports can largely affect the catalytic performance of metal nanoparticles, but the underlying principles are not yet fully understood. Here the authors demonstrate that metal-support interfacial compatibility of Ru/TiO 2 can critically control the metal-support interaction modes and the catalytic performances in CO 2 hydrogenation.

Bacterial infections triggered by patient or healthcare worker contact with surfaces are a major cause of medically acquired infections. By controlling the kinetics of tetrabutyl titanate hydrolysis and condensation during the sol–gel process, it is possible to regulate the content of Ti 3+ and oxygen vacancies (OVs) in TiO 2 , and adjust the associated visible light-induced photocatalytic performance and anti-bacterial adhesion properties. The results have shown that the Ti 3+ content in TiO 2 was 9.87% at the calcination temperature of the reaction system was 300 °C and pH was 1.0, corresponding to optimal photocatalytic and hydrophilic properties. The formation of a hydrated layer on the superhydrophilic surface provided resistance to bacterial adhesion, preventing cross-contamination on high-touch surfaces. The excellent photocatalytic self-cleaning performance and anti-bacterial adhesion properties can be attributed to synergistic effects associated with the high specific surface area of TiO 2 nanoparticles, the mesoporous structure, and the presence of Ti 3+ and OVs. The formation of superhydrophilic self-cleaning surfaces under visible light can serve as the basis for the development of a new class of anti-bacterial adhesion materials.

Lithium-doped anatase-TiO 2 nanoparticles (Li x Ti 1-x O 2 NPs, x = 0, 0.05, 0.10, 0.15 and 0.20) could be synthesized by a simple sol–gel process. X-ray diffraction (XRD) results displayed the tetragonal (space group: I41/amd) of polycrystalline TiO 2 anatase phase. The spectroscopy results of Raman and FT-IR confirmed the anatase phase of TiO 2 through the specific modes of metal oxides vibration in the crystalline TiO 2 . Surfaces micrographs by scanning electron microscope (SEM) of agglomerated Li x Ti 1-x O 2 NPs showed a spongy like morphology. Transmission electron microscope (TEM) illustrated a cuboidal shape of dispersed NPs with particle size distributed in a narrow range 5–10 nm. Bruanauer Emmett-Teller (BET) results showed the increased surface area of Li x Ti 1−x O 2 NPs with increasing Li content. Li x Ti 1-x O 2 NPs (x = 0.05–0.20) working electrodes illustrated a pseudocapacitive behavior with excellent electrochemical properties through the whole cycles of GCD test. Interestingly, Li 0.1 Ti 0.9 O 2 NPs electrode illustrated a high performance in terms of maximum specific capacitance 822 F g −1 at 1.5 A g −1 in 0.5 M Li 2 SO 4 electrolyte, with excellent capacitive retention 92.6% after 5000 cycles GCD test.