Chongshen Guo

Morphology-Controlled Synthesis of W18O49 Nanostructures and Their Near-Infrared Absorption Properties

The morphology-controlled synthesis and near-infrared (NIR) absorption properties of W(18)O(49) were systematically investigated for the application of innovative energy-saving windows. Various morphologies of W(18)O(49), such as nanorods, nanofibers, nanograins, nanoassembles, nanoplates, and nanoparticles, with various sizes were successfully synthesized by solvothermal reactions using organic alcohols as reaction media and WCl(6), W(EtO)(6), and WO(3) solids as the tungsten source. W(18)O(49) nanorods of less than 50 nm in length showed the best optical performance as an effective solar filter, which realized high transmittance in the visible region as well as excellent shielding properties of NIR light. Meanwhile, the W(18)O(49) nanorods also exhibited strong absorption of NIR light and instantaneous conversion of the absorbed photoenergy to the local heat.

Facile synthesis of homogeneous CsxWO3 nanorods with excellent low-emissivity and NIR shielding property by a water controlled-release process

A systematic investigation of the synthesis of homogenous CsxWO3 nanorods by a designed water-controlled release process was carried out. The results revealed that the uniform rod-like CsxWO3 nanoparticles with a Cs/W atomic ratio of ca. 0.33 can be obtained by using 20 vol% CH3COOH–80 vol% CH3CH2OH mixed solution as a reaction solvent at 240 °C for 20 h. The morphology of products were changed depending on the speed of water-releasing process, meanwhile, the Cs/W atomic ratio could be controlled by both the amount of released water and the reaction temperature. CsxWO3 nanorods showed a high transmittance in the visible light region and excellent shielding ability of near infrared (NIR) lights, indicating that CsxWO3 nanorods have a suitable characteristic as solar filter applications.

Synthesis of W18O49 Nanorod via Ammonium Tungsten Oxide and Its Interesting Optical Properties

W(18)O(49) nanorods were synthesized by pyrolyzing (NH(4))(x)WO(3+x/2) nanorods precursors, which were prepared by a hydrothermal reaction using sulfate as a structure-directing agent, in a reductive atmosphere of H(2)(5 vol %)/N(2) at 500 °C for 1 h. W(18)O(49) nanorods showed high transmittance in the visible region as well as excellent shielding properties of NIR lights. A simulated experiment revealed that excellent heat insulating performance can be realized by applying a 70% visible light transparent W(18)O(49) coating on a quartz glass. Meanwhile, the W(18)O(49) nanorods also showed strong absorption of NIR light and instantaneous conversion of photoenergy to heat. In a word, W(18)O(49) nanorods hold interesting optical properties and are a promising material in a wide range of applications.

Synthesis of One-Dimensional Potassium Tungsten Bronze with Excellent near-Infrared Absorption Property

Potassium tungsten oxide nanofibers were successfully synthesized via a facile hydrothermal reaction route in the presence of sulfate. After reduction under a reductive atmosphere of H(2)(5 vol %)/N(2), the potassium tungsten oxide transformed to potassium tungsten bronze. Because of the lack of free electrons, the potassium tungsten oxide (K(x)WO(3+x/2)) showed no NIR shielding performance; however, the potassium tungsten bronze (K(x)WO(3)) showed promising optical characteristics such as high transmittance for visible light, as well as high shielding performance for near-infrared lights, indicating its potential application as a solar filter. Meanwhile, the potassium tungsten bronze (K(x)WO(3)) showed strong absorption of near-infrared light and instantaneous conversion of photoenergy to heat.

Novel synthesis of homogenous CsxWO3 nanorods with excellent NIR shielding properties by a water controlled-release solvothermal process

Nanosize homogenous rod-like tungsten bronze CsxWO3 with excellent NIR shielding ability was successfully synthesized by a novel and facile water controlled-release solvothermal process (WCRSP).

WO3−x sensitized TiO2 spheres with full-spectrum-driven photocatalytic activities from UV to near infrared

To make full use of solar energy for photocatalytic reactions, in this work, we developed full-spectrum-responsive photocatalysts with noteworthy photocatalytic activities under either UV, visible or even near infrared irradiation for the photodegradation of methylene blue. The core-shell structure of TiO2@WO3-x is designed from the consideration of combining the full-spectrum photo-absorption properties of WO3-x with the excellent semiconductor properties of TiO2. As expected, the WO3-x sensitized TiO2 sphere gives rise to a prominently strong optical absorption in the whole region of 300-2500 nm and thus displays desired photocatalytic properties for the full utilization of all solar energy, especially in the unexploited NIR part, which accounts for most of the sunlight. Encouraged by the above exciting photocatalytic outcome, we then go further to propose a plausible mechanism for interpreting the NIR-driven photocatalytic properties, which is based on the hypothesis of low-valent W5+ site induced free electrons and evidence-based ESR results.

Near-infrared absorption properties of RbxWO3 nanoparticles

The rubidium tungsten bronze (RbxWO3) nanoparticles were synthesized by a solvothermal process in CH3COOH–C2H5OH mixed solutions for the application to near-infrared absorption materials. The as-obtained powder products were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and UV-Vis-NIR spectra. The morphologies of samples were greatly changed as large irregular aggregates, aggregates of rod-like and irregular shaped nanoparticles and rod-like microparticles with increasing content of acetic acid in the starting solution. The sample synthesized in a 20 vol.% CH3COOH to 80 vol.% C2H5OH mixed solution consisted of the agglomerated particles of 50–100 nm in diameter, showing a highly disordered microstructure. Promoted by this disordered nature, the thin film of RbxWO3 nanoparticles realized excellent absorption of near-infrared light, meanwhile, it selectively transmitted the major part of visible light.

The near infrared absorption properties of W18O49

The urchin-like W18O49 nanoparticles showed high transparency in the visible region, strong absorption of near-infrared light and instantaneous conversion of the absorbed photo-energy to local heat.

Synthesis of hierarchically structured ZnO spheres by facile methods and their photocatalytic deNOx properties

This paper presents novel and facile methods for the fabrication of a series ZnO spheres by template-free, carbon template and hydrated-salt assisted solvothermal process, respectively. Phase purity and crystalline structure of the products were studied by X-ray diffraction analysis. SEM was employed to investigate the morphology and the fabrication of the monodisperse. BET analysis revealed that the as-prepared samples possessed huge specific surface area. UV-vis diffuse reflectance spectroscopy showed that these ZnO hollow spheres have a higher absorption. The as-prepared samples showed excellent photocatalytic activity for the decomposition of NOx gas under both visible-light and UV light irradiation (λ>510, 400, 290nm), being superior to that of commercial TiO2 powders.

Ce0.5Zr0.4Sn0.1O2/Al2O3 catalysts with enhanced oxygen storage capacity and high CO oxidation activity

Ce0.5Zr0.4Sn0.1O2/Al2O3 catalysts were prepared by a coprecipitation route using Ce(NH4)2(NO3)6, Zr(NO3)3·2H2O, SnCl4·5H2O and Al2O3 as the starting materials, and were evaluated as a promoter in automotive catalysis by X-ray diffraction, transmission electron microscopy and the Brunauer–Emmet–Teller (BET) technique. The oxygen storage capacity (OSC) values of the samples were measured using thermogravimetric-differential thermal analysis at 600 °C with a continuous flow of CO–N2 gas and air alternately. The CO oxidation activity of the synthesized sample was evaluated via a gas FTIR spectrometer for analysis of gas compositions. The Ce0.5Zr0.4Sn0.1O2/γ-Al2O3 composite possessed excellent thermal stability, enhanced OSC values, and high CO oxidation activity at the low temperatures even after calcination at 1000 °C for 20 h.