Chuanyi Wang

A comparative study of nanometer sized Fe(III)-doped TiO2 photocatalysts: synthesis, characterization and activity

Fe(III)-doped TiO2 nanoparticles have been prepared in three different ways using inorganic or organic precursors, respectively. Transmission electron microscopic (TEM) structure characterization of the obtained particles reveals that TiO2 particles with and without the Fe(III) dopant possess the crystal structure of anatase. Cryo-TEM of vitrified samples confirms earlier assumptions that TiO2 nanoparticles tend to form three-dimensional networks in solution. A novel energy transfer mechanism is suggested employing these three-dimensional networks as antenna systems which lead to improved photocatalytic activities of the colloidal preparations. The performance of the nanostructured TiO2 with and without Fe-dopant for the photocatalytic oxidation of methanol producing HCHO is strongly dependent on the preparations and the Fe-content. Fe(III)-doped TiO2 nanoparticles prepared from organic precursors by the novel method (≤2.5 atom% Fe) exhibit a greatly enhanced photocatalytic activity (quantum yield of HCHO up to ca. 15%).

Self-Assembly of Perylene Imide Molecules into 1D Nanostructures: Methods, Morphologies, and Applications

Methods, Morphologies, and Applications Shuai Chen,†,‡ Paul Slattum, Chuanyi Wang,*,† and Ling Zang* †Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011, China ‡The Graduate School of Chinese Academy of Science, Beijing 100049, China Nano Institute of Utah and Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States Vaporsens Inc., Salt Lake City, Utah 84112, United States

Selective photocatalytic N2 fixation dependent on g-C3N4 induced by nitrogen vacancies

Photoreduction of N2 is among the most interesting and challenging methods for N2 fixation under mild conditions. In this study, we determined that nitrogen vacancies (NVs) could endow graphitic carbon nitride (g-C3N4) with the photocatalytic N2 fixation ability. Photocatalytic N2 fixation induced by NVs is free from the interference of other gases. The reason is that NVs could selectively adsorb and activate N2 because NVs have the same shape and size as the nitrogen atom in N2. In addition to this, NVs could also improve many other properties of g-C3N4 to support photocatalytic N2 fixation. These new findings could elucidate the design of efficient photocatalysts for photocatalytic N2 fixation.

Visible-Light-Assisted Electrocatalytic Oxidation of Methanol Using Reduced Graphene Oxide Modified Pt Nanoflowers-TiO2 Nanotube Arrays

In this work, Pt nanoflowers deposited on highly ordered TiO2 nanotube arrays (TNTs) by modification of reduced graphene oxide (RGO) nanostructures have been synthesized. The ternary complex (Pt-TNTs/RGO) displays efficient electrocatalytic performance toward methanol oxidation in alkaline medium. The electrochemical impedance spectroscopy (EIS) and responsive photocurrent results indicate that the presence of graphene could effectively promote charge separation during electrocatalytic process. Interestingly, with assistance of visible light illumination, the electrocatalytic activity and stability of the ternary complex electrode toward methanol oxidation are distinctly improved. Both electro- and photo-catalytic processes for methanol oxidation contribute to the enhanced catalytic performance and stability. Moreover, the ternary electrode also displays efficient photoelectrocatalytic degradation of methylene blue (MB) under visible light illumination. The present work sheds light on developing highly efficient and long-term stability catalysts for methanol oxidation with assistance of visible-light illumination.

A novel preparation of iron-doped TiO2 nanoparticles with enhanced photocatalytic activity

FeIII-doped TiO2 nanoparticles prepared from organic precursors (⩽2.5 atom% Fe) exhibit strongly enhanced photocatalytic activity as demonstrated by the quantum yields measured for the formation of formaldehyde by photocatalyzed oxidation of methanol in aqueous solution (Φ up to ca. 15%).

Green synthesis of shape-defined anatase TiO2 nanocrystals wholly exposed with {001} and {100} facets

Anatase TiO(2) nanocuboids wholly exposed with high-energy {001} and {100} facets were successfully synthesized by a novel, environmentally benign synthetic strategy using acid-delaminated vermiculite (DVMT) and tetramethylammonium hydroxide as synergistic morphology-controlling reagents, where the DVMT layers act as effective hard template selectively stabilizing the {001} facets of TiO(2).

In situ Electron Microscopy Investigation of Fe(III)-doped TiO2 Nanoparticles in an Aqueous Environment

Three-dimensional networks of Fe(III)-doped TiO2 nanoparticles (2–4 nm) prepared from organic precursors are detected by Cryo-TEM (transmission electron microscopy) in an aqueous environment. High-resolution TEM studies show that the nanoparticles prefer to align along their crystallographic orientation. A novel energy transfer mechanism is suggested in which these three-dimensional networks act as antenna systems thus leading to an enhanced photocatalytic activity of the colloidal preparations.

Facile Synthesis of Defective TiO2-x Nanocrystals with High Surface Area and Tailoring Bandgap for Visible-light Photocatalysis.

A facile hydrothermal approach has been developed to prepare defective TiO2−x nanocrystals using Ti(III)-salt as a precursor and L-ascorbic acid as reductant and structure direction agent. The prepared TiO2−x nanocrystals are composed of a highly crystallized TiO2 core and a disordered TiO2−x outer layer, possessing high surface area, controlled oxygen vacancy concentration and tunable bandgap via simply adjusting the amount of added L-ascorbic acid. The defective TiO2−x shows high photocatalytic efficiency in methylene blue and phenol degradation as well as in hydrogen evolution under visible light, underlining the significance of the present strategy for structural and bandgap manipulation in TiO2-based photocatalysis.

Ti3+-self doped brookite TiO2 single-crystalline nanosheets with high solar absorption and excellent photocatalytic CO2 reduction

Black brookite TiO2 single-crystalline nanosheets with outstanding photocatalytic activity toward CO2 reduction is prepared by a facile oxidation-based hydrothermal reaction method combined with post-annealing treatment. Large amount of Ti3+ defects are introduced into the bulk of brookite nanoparticles, which increases the solar energy absorption and enhances the photocatalytic activity.

Enhanced photocatalytic H2 evolution over CdS/Au/g-C3N4 composite photocatalyst under visible-light irradiation

A novel heterojunction structured composite photocatalyst CdS/Au/g-C3N4 has been developed by depositing CdS/Au with a core (Au)-shell (CdS) structure on the surface of g-C3N4. The photocatalytic hydrogen production activity of the developed photocatalyst was evaluated under visible-light irradiation (λ > 420 nm) using methanol as a sacrificial reagent. As a result, its activity is about 125.8 times higher than that of g-C3N4 and is even much higher than that of Pt/g-C3N4. The enhancement in photocatalytic activity is attributed to efficient separation of the photoexcited charges due to the anisotropic junction in the CdS/Au/g-C3N4 system.