Xiangdong Wang

Bio: Xiangdong Wang is an academic researcher from Xi'an Jiaotong University. The author has contributed to research in topics: Photocatalysis & Mesoporous material. The author has an hindex of 8, co-authored 12 publications receiving 172 citations.

Synthesis and characterization of N-doped TiO2 loaded onto activated carbon fiber with enhanced visible-light photocatalytic activity

Abstract: Nano-sized TiO2 particles are only excited under ultraviolet light irradiation and are difficult to be separated and recovered from the solution after the degradation reaction is complete. In this work, we have reported that N-doped TiO2 particles prepared via a sol–gel method were loaded onto activated carbon fiber (ACF) to fabricate a series of novel N-doped TiO2/ACF photocatalysts. The prepared N-doped TiO2 particles were in the anatase phase and the mean size of the particles was about 15 nm when heat-treated at 500 °C. Nitrogen atoms were incorporated into the surface of TiO2 mainly as interstitial nitrogen and molecularly chemisorbed γ-N2 molecules, and a little as substitutional nitrogen. N-doped TiO2 particles exhibit an evident red shift in the band edge and an obvious increase in visible region absorption, and the particles as a single particle are homogeneously dispersed on the surface of ACF. The results of the photocatalytic degradation of methyl orange show that N-doped TiO2/ACF photocatalysts exhibit enhanced visible light photocatalytic activity. This could be attributed to the synergistic effect between the strong adsorption of the ACF and the visible light photocatalytic activity by N-doped TiO2. The photocatalysts could be used for multiple degradation cycles without a decrease in the photocatalytic activity.

Black TiO 2 synthesized via magnesiothermic reduction for enhanced photocatalytic activity

Abstract: Utilizing solar energy for hydrogen evolution is a great challenge for its insufficient visible-light power conversion. In this paper, we report a facile magnesiothermic reduction of commercial TiO2 nanoparticles under Ar atmosphere and at 550 °C followed by acid treatment to synthesize reduced black TiO2 powders, which possesses a unique crystalline core–amorphous shell structure composed of disordered surface and oxygen vacancies and shows significantly improved optical absorption in the visible region. The unique core–shell structure and high absorption enable the reduced black TiO2 powders to exhibit enhanced photocatalytic activity, including splitting of water in the presence of Pt as a cocatalyst and degradation of methyl blue (MB) under visible light irradiation. Photocatalytic evaluations indicate that the oxygen vacancies play key roles in the catalytic process. The maximum hydrogen production rates are 16.1 and 163 μmol h−1 g−1 under the full solar wavelength range of light and visible light, respectively. This facile and versatile method could be potentially used for large scale production of colored TiO2 with remarkable enhancement in the visible light absorption and solar-driven hydrogen production.

Nitrogen-doped titanium dioxide (N-doped TiO2) for visible light photocatalysis

Abstract: TiO2 is an effective and well-known photocatalyst for water and air purification, but its practical applications in visible light-assisted chemical reactions are hindered mainly by its poor visible light absorption capacity. Nitrogen-doped TiO2 (N-doped TiO2) has attracted considerable attention as a photocatalyst, and rapid progress has been made in enhancing the photocatalytic efficiency of TiO2 under visible light irradiation. N-doped TiO2 exhibits broad absorption in the visible region, which can allow the utilization of a large part of the solar spectrum. This might be useful for environmental and energy applications, such as the photocatalytic degradation of organic pollutants, solar cells, sensors, and water splitting reactions. This review focuses on the major developments in the synthesis of N-doped TiO2 and its possible applications in the photocatalytic degradation of organic pollutants and environmental remediation under visible light irradiation.

Photocatalytic Activity Improvement and Application of UV-TiO2 Photocatalysis in Textile Wastewater Treatment: A Review

Abstract: Treatment of textile wastewater using titanium dioxide (TiO2) photocatalysis has been started from the last decade and reached attention to the researchers because of its versatile application. The variety of applications of TiO2 as a photocatalyst has been taken place because of low operating temperature, biologically inert nature, low energy consumption, water insolubility, ease availability and photoactivity, less toxicity, high chemical stability, suitable flat band potential, narrow band gap and environmentally benign. The successful and efficient application of photocatalysis depends on quality of photocatalyst, nature of pollutants, and source of light, which should be in close contact with each other. The TiO2 photocatalyst is used for the effluent treatment of textile wastewater in the presence of ultraviolet (UV) irradiation. Heterogeneous UV-TiO2 photocatalysis is capable to remove organic pollutants from textile wastewater, which has been widely studied and the technology also being commercialized in many developing countries in the world. This review focuses on the mechanism of UV-TiO2 photocatalysis, modification of TiO2 photocatalyst, and application of doping and co-doping in order to improve the photocatalytic activity in wastewater treatment. In addition, the review conveys comprehensive and fundamental assessments of the photocatalytic activity for the removal of organic dyes and phenolic compounds from textile wastewater.

Titanium Dioxide: From Engineering to Applications

Abstract: Titanium dioxide (TiO2) nanomaterials have garnered extensive scientific interest since 1972 and have been widely used in many areas, such as sustainable energy generation and the removal of environmental pollutants. Although TiO2 possesses the desired performance in utilizing ultraviolet light, its overall solar activity is still very limited because of a wide bandgap (3.0–3.2 eV) that cannot make use of visible light or light of longer wavelength. This phenomenon is a deficiency for TiO2 with respect to its potential application in visible light photocatalysis and photoelectrochemical devices, as well as photovoltaics and sensors. The high overpotential, sluggish migration, and rapid recombination of photogenerated electron/hole pairs are crucial factors that restrict further application of TiO2. Recently, a broad range of research efforts has been devoted to enhancing the optical and electrical properties of TiO2, resulting in improved photocatalytic activity. This review mainly outlines state-of-the-art modification strategies in optimizing the photocatalytic performance of TiO2, including the introduction of intrinsic defects and foreign species into the TiO2 lattice, morphology and crystal facet control, and the development of unique mesocrystal structures. The band structures, electronic properties, and chemical features of the modified TiO2 nanomaterials are clarified in detail along with details regarding their photocatalytic performance and various applications.

Recent Progress on Titanium Dioxide Nanomaterials for Photocatalytic Applications.

Abstract: Environmental and energy problems have drawn much attention owing to rapid population growth and accelerated economic development For instance, photocatalysis, "a green technology", plays an important role in solar-energy conversion owing to its potential to solve energy and environmental problems Recently, many efforts have been devoted to improving visible-light photocatalytic activity by using titanium dioxide as a photocatalyst as a result of its wide range of applications in the energy and environment fields However, fast charge recombination and an absorption edge in the UV range limit the photocatalytic efficiency of TiO2 under visible-light irradiation Many investigations have been undertaken to overcome the limitations of TiO2 and, therefore, to enhance its photocatalytic activity under visible light The present literature review focuses on different strategies used to promote the separation efficiency of electron-hole pairs and to shift the absorption edge of TiO2 to the visible region Current synthesis techniques used to elaborate several nanostructures of TiO2 -based materials, recent progress in enhancing visible photocatalytic activity, and different photocatalysis applications will be discussed On the basis of the studies reported in the literature, we believe that this review will help in the development of new strategies to improve the visible-light photocatalytic performance of TiO2 -based materials further