Highly active Cr-doped, Ni-doped and Mo-doped TiO2 photocatalysts were synthesized by a sol–gel method. The synthesized catalysts were characterized by UV–DRS, BET, XRD, FE-SEM–EDS, TEM and XPS. Metal doping decreased the band gap of TiO2 to 2.83 eV for Mo-doped TiO2 and Ni-doped TiO2. The activity of the synthesized photocatalysts was evaluated by studying the degradation of MB as a model pollutant under both UV and solar irradiation. The Mo/TiO2 catalyst achieved 98% degradation under solar light within 120 min. The activity of the catalysts was in the order Ni-doped TiO2   7 and followed pseudo-first order kinetics. Degradation by-products were analyzed on HR-LCMS and a mechanism is proposed.

Solar light-assisted photocatalytic degradation of methylene blue with Mo/TiO 2 : a comparison with Cr- and Ni-doped TiO 2

Easily recoverable photocatalysts with high activities are desirable in photocatalytic wastewater treatment. In this paper, we reported a low-temperature solution synthesis of Ni-doped flower-like rutile TiO2, which possessed an activity four times that of the commercial Degussa P25 TiO2 nanoparticles when utilized to assist photodegradation of rhodamine B in water under the illumination of a Xe lamp. More importantly, the micrometer-sized aggregations facilitate the subsequent recovery from the slurry. Hydrogen titanate nanowires were firstly achieved by interactions between metallic Ti and a H2O2 aqueous solution at 80 °C. A subsequent immersing at 80 °C of the titanate nanowires in a H2SO4 aqueous solution containing NiSO4 transformed the nanowires to rutile TiO2 nanoflowers, which were assembled by single-crystalline nanorods. The transformation proceeded through dissolution–precipitation in the acidic environment, which in sequence led to the growth of rutile nanorods that assemble the nanoflowers, via an oriented attachment mechanism. When utilized to assist photodegradation of rhodamine B in water under Xe lamp illumination, the Ni-free rutile TiO2 nanoflowers exhibited an activity double that of P25. The appropriate doping of Ni further improved the efficiency to four times that of P25. The enhanced photocatalytic activity can be attributed to both the high specific surface area of ca. 118 m2 g−1, and the appropriate Ni-doping that favors both the light harvesting and the charge separation.

Ni-doped rutile TiO2 nanoflowers: low-temperature solution synthesis and enhanced photocatalytic efficiency

Optimization of physicochemical properties of TiO2 anatase for organophosphorus remediation remains challenging. One approach is to use anatase nanofibers, prepared from hydrothermally synthesized titanates. Charge densities and potentials of anatase nanofibers were determined from atomic force microscopy force–curve measurements using the modified Derjaguin, Landau, Verwey, Overbeek theory, which includes roughness and hydration forces, in the pH range 4–9. Calculated values were −0.007 to −0.03 C m–2 and −70 to −150 mV, respectively. In contrast, at neutral pH, the magnitudes of diffuse layer surface charge densities and potentials have a minimum in anatase nanoparticles. These observations and zeta-potential results suggest that nanofiber surfaces are more acidic compared with nanoparticles. This is consistent with nanofibers having ∼3-fold higher adsorption for organophosphorus methyl parathion (pH ≈ 7). The resulting adsorption includes contributions from (1) charge accumulation at local coordination...

Role of TiO2 Anatase Surface Morphology on Organophosphorus Interfacial Chemistry

In this review, we provide an overview of recent progress in nanocarbons with different dimensions as noble-metal-free co-catalysts for photocatalysts. We put emphasis on the interface engineering between nanocarbon co-catalysts and various semiconductor photocatalysts and the novel properties generating of nanocarbon co-catalysts, also including the synthesis and application of nanocarbon-based photocatalyst composites.

https://www.mdpi.com/2073-4344/6/8/111/pdf

Nanocarbons with Different Dimensions as Noble-Metal-Free Co-Catalysts for Photocatalysts

Layered titanate hierarchical spheres as a promising pseudocapacitive electrode material for high rate lithium ion batteries

The nickel-doped titanium dioxide nanotubes were prepared by Sol-gel and hydrothermal method and used to photodecompose methylene blue (MB) in liquid phase under visible light irradiation. The anatase-type titania nanotubes were shown to be hollow scrolls with outer diameter of about 10–15 nm and length of several hundred nanometers. The photocatalytic properties of Ni-doped titanium dioxide nanotubes and nanopowders were studied by degrading of MB. The results show that appropriate content of nickel can effectively enhance the photocatalytic activity of titanium dioxide nanotubes.

Preparation and Photocatalytic Property of Nickel-Doped Titanium Dioxide Nanotubes

Preparation and characterization of Lepidocrocite titanate nanofibers

A simple method to form single-crystal silica nanotubes in a low relative temperature is reported. A result of tridymite nanotubes in single-crystal structure, which was obtained by pregained amorphous silica nanotubes heated to 471 K for 5 h in the presence of glycol and potassium hydroxide is described. The results of XRD and TEM reveal that single-crystal tridymite nanotube was prepared.

Preparation and Characterization of Single-Crystal Silica Nanotubes

The purpose of this study was to investigate the possibility for parenteral delivery of Gamma-linolenic acid methyl ester without chemical modification using a microemulsion. Microemulsions composed of gamma-linolenic acid methyl ester and Tween 80 were prepared using PEG 400 as a cosurfactant. The effect of formulation variables on the particle size of the microemulsion was investigated. TEM image indicates the liquid droplets of the microemulsion are spheral shape. The mean droplet size of microemulsion system (Tween 80: GLA = 3:1) by PCS was about 50 nm and no changes were noted for at least six months.

Physicochemical Characterization and Evaluation of a Microemulsion System for Gamma-Linolenic Acid Methyl Ester

To improve the photocatalytic property of TiO2, Fe3+-doped TiO2 nanotubes were fabricated by sol-gel and hydrothermal method. The prepared materials were characterized by XRD and TEM techniques. The photocatalytic properties of samples were evaluated based on the degradation of aqueous methylene blue solution under visible light. The obtained anatase-type titania nanotubes were hollow scrolls with outer diameter approximately 13 nm and length about 90–120 nm. The results showed that appropriate content of ferrum ion can improve the photocatalytic activity of titanium dioxide nanotubes significantly.

Xiaoxi Gao

Papers

Preparation and Photocatalytic Property of Nickel-Doped Titanium Dioxide Nanotubes

Preparation and characterization of Lepidocrocite titanate nanofibers

Preparation and Characterization of Single-Crystal Silica Nanotubes

Physicochemical Characterization and Evaluation of a Microemulsion System for Gamma-Linolenic Acid Methyl Ester

Preparation and Photocatalytic Property of Fe-Doped Titanium Dioxide Nanotubes