Shiping Xu

3D hierarchical golden wattle-like TiO2 microspheres: polar acetone-based solvothermal synthesis and enhanced water purification performance

3D hierarchical TiO2 microsphere structures self-assembled from 1D nanostructures have attracted considerable research attention due to their unique microstructures and properties, and non-polar solvent-based solvothermal methods have been proved to be effective techniques to synthesize such structures. However, to the best of our knowledge, no successful products have been reported based on polar solvents in the available literature. Herein, for the first time, uniform and sophisticated golden wattle (Acacia pycnantha)-like TiO2 microsphere structures, self-assembled from highly crystallized and radially grown 1D rutile nanorods, were successfully synthesized via a template-free solvothermal reaction using only polar acetone as the solvent in the presence of hydrochloric acid (HCl). The obtained samples showed good water purification performance, even superior to Degussa P25, owing to their unique 1D nanorod building block structure, fast electron transfer rate, excellent light harvesting capability and good crystallinity. In addition, a three-step growth mechanism of the golden wattle-like TiO2 microspheres was proposed based on a time-dependent morphology and crystal form evolution process. The synthetic strategy for the golden wattle-like TiO2 microspheres employed in this study provides new insights into the design of 3D hierarchical TiO2 structures for practical environmental purification applications.

Facile one-pot synthesis of carbon incorporated three-dimensional hierarchical TiO2 nanostructure for highly efficient pollutant removal

Herein, a carbon incorporated three-dimensional (3D) hierarchical TiO2 nanostructure (CRF-TiO2) was successfully synthesized via a facile one-pot route by coupling TiCl3 hydrolysis–oxidation with resorcinol–formaldehyde (RF) reaction without any surfactant. The fabricated CRF-TiO2 showed an interesting 3D hierarchical and mesoporous structure, possessed relatively large specific surface area and excellent light absorption capability, and the TiO2 in the final product was an anatase–rutile mixture with mature crystallinity. All of the above characteristics endow the prepared CRF-TiO2 with superior adsorption capability and photocatalytic activity compared to Degussa P25. As a result, with the presence of CRF-TiO2, pollutants in water could be rapidly separated from the aqueous phase via adsorption, which can ideally meet the requirements of fast water purification, and then the pollutants would be efficiently decomposed by a photocatalysis process under both UV and visible light irradiation to completely fulfill the pollutant removal target. The synthetic strategy for CRF-TiO2 employed in this study provides an effective solution for the synthesis of carbon incorporated 3D hierarchical TiO2 architectures, and can introduce new insights to design TiO2-based photocatalysts for practical environmental purification applications.

Enhanced degradation of ciprofloxacin by graphitized mesoporous carbon (GMC)-TiO 2 nanocomposite: Strong synergy of adsorption-photocatalysis and antibiotics degradation mechanism

In order to achieve remarkable synergy between adsorption and photocatalysis for antibiotics elimination from water, in this study, a graphitized mesoporous carbon (GMC)-TiO2 nanocomposite was successfully synthesized by an extended resorcinol-formaldehyde (R-F) method. In the composite, the lamellar GMC nanosheets possessed large specific surface area and mesoporous structure, and could adsorb and enrich antibiotics effectively. This could not only reduce the antibiotic concentration in water shortly, but also greatly increase the chances for antibiotics to contact with and be degraded by photocatalysts and active species. Interestingly, GMC could also facilitate the transportation of photogenerated electrons to further improve the photocatalytic efficiency of TiO2, and 15 mg/L ciprofloxacin (CIP) could be totally mineralized in 1.5 h. Meanwhile, the biological inhibition of reaction solution on luminescence bacteria decreased obviously with antibiotics degradation until non-toxicity, reinforcing the thorough elimination of antibiotics. Besides, from the viewpoint of organic chemistry, several plausible CIP degradation pathways were established using HPLC-MS technique, and an interesting intermediate with five-membered ring structure was firstly proposed, which is helpful to deeply understand CIP degradation. Strong synergy between adsorption and photocatalysis, along with quick and efficient antibiotics elimination, double confirm the great potential of GMC-TiO2 nanocomposite for practical antibiotic wastewater purification.