Zipeng Xing

Black TiO 2 nanobelts/g-C 3 N 4 nanosheets Laminated Heterojunctions with Efficient Visible-Light-Driven Photocatalytic Performance

Black TiO2 nanobelts/g-C3N4 nanosheets laminated heterojunctions (b-TiO2/g-C3N4) as visible-light-driven photocatalysts are fabricated through a simple hydrothermal-calcination process and an in-situ solid-state chemical reduction approach, followed by the mild thermal treatment (350 °C) in argon atmosphere. The prepared samples are evidently investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption, and UV-visible diffuse reflectance spectroscopy, respectively. The results show that special laminated heterojunctions are formed between black TiO2 nanobelts and g-C3N4 nanosheets, which favor the separation of photogenerated electron-hole pairs. Furthermore, the presence of Ti3+ and g-C3N4 greatly enhance the absorption of visible light. The resultant b-TiO2/g-C3N4 materials exhibit higher photocatalytic activity than that of g-C3N4, TiO2, b-TiO2 and TiO2/g-C3N4 for degradation of methyl orange (95%) and hydrogen evolution (555.8 μmol h−1 g−1) under visible light irradiation. The apparent reaction rate constant (k) of b-TiO2/g-C3N4 is ~9 times higher than that of pristine TiO2. Therefore, the high-efficient laminated heterojunction composites will have potential applications in fields of environment and energy.

3D urchin-like black TiO2−x/carbon nanotube heterostructures as efficient visible-light-driven photocatalysts

3D urchin-like black TiO2−x/CNT heterostructures are successfully fabricated via a facile one-pot solvothermal reaction combined with a subsequent in situ solid-state chemical reduction approach. The as-prepared photocatalysts are characterized in detail via X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The results demonstrate that the obtained black TiO2−x/CNT heterostructures exhibit a 3D urchin-like heterojunction structure, and Ti3+ is doped into the lattice of anatase TiO2. This unique 3D structure with abundant active sites can enhance light scattering capability, and the Ti3+ self-doping defective TiO2 with a narrow bandgap can promote visible-light photocatalytic activity. Therefore, the TiO2−x/CNT heterostructures exhibit unparalleled high visible-light-driven photocatalytic activity and electrochemical properties. The visible-light-driven photocatalytic degradation rate for methylene orange is up to 99.6% and the hydrogen production rate is as high as 242.9 μmol h−1 g−1, which is ascribed to the 3D urchin-like structure offering abundant active sites, the heterostructures resulting in the separation of photogenerated charge carriers, and the Ti3+ self-doping narrowing the bandgap and favoring visible light absorption.

Mesoporous black TiO2-x/Ag nanospheres coupled with g-C3N4 nanosheets as 3D/2D ternary heterojunctions visible light photocatalysts

3D mesoporous black TiO2-x/Ag nanosphere coupled with 2D g-C3N4 sheet ternary heterojunctions are successfully fabricated through a facile evaporation-induced self-assembly (EISA) process and photodeposition method, followed by a mild calcination (350°C) under an argon atmosphere after an in situ solid-state chemical reduction strategy. The resultant mesoporous black TiO2-x/Ag/g-C3N4 ternary heterojunctions with narrow band gap of∼2.27eV possess a relative high specific surface area of∼100m2g-1, main pore size of 6.2nm and the highest visible-light-driven photocatalytic property for degradation of methyl orange (97%) and methylene blue (99%). The apparent reaction rate constants (k) of mesoporous black TiO2-x/Ag/g-C3N4 for methyl orange and methylene blue are∼9 and 11 times higher than that of pristine TiO2. The possible mechanism is proposed, and the excellent photocatalytic property can be ascribed to the introduction of Ti3+ self-doping and g-C3N4, which favor the visible light absorption and the separation of electron-hole pairs, the surface plasma resonance effect of Ag nanoparticle, and the mesoporous networks offer more surface active sites.

Facile synthesis of high-thermostably ordered mesoporous TiO2/SiO2 nanocomposites: An effective bifunctional candidate for removing arsenic contaminations.

High-thermostably ordered mesoporous TiO2/SiO2 nanocomposites are successfully prepared through evaporation-induced self-assembly method combined with ethylenediamine bounding strategy and subsequent high-temperature calcinations (700°C). The prepared samples are characterized in detail by thermogravimetric-differential scanning calorimetry, X-ray diffraction, Raman, transmission electron microscopy and N2 adsorption. The results indicate that the samples are ordered mesostructure and the presence of SiO2 inhibits the anatase-to-rutile phase transformation at high temperature. Significantly, the experimental results show that the high-thermostably ordered mesoporous TiO2/SiO2 nanocomposites play bifunctional roles on effectively adsorbing As (III) and completely oxidizing higher toxic As (III) to lower toxic As (V) under various pH values by one time. Moreover, after recycling for ten times the composites still keep wonderful photocatalytic and adsorption performance. The subtly nanostructured bifunctional composites will have broad application prospects in contaminated water treatment.

Structure and Properties of Noncrystalline Nano-Al(OH)3 Reclaimed from Carbonized Residual Wastewater Treatment Sludge

Performance of wastewater treatement sludge-carbon (SC) can be evidently improved by removing the inorganic fractions. A novel investigation for recovery of Al from acid leaching of SC and synthesis of nano-Al(OH)(3) has been conducted. Results show that the sodium aluminates with high purity can be obtained by effectively dissolving the inorganic fractions from SC and by further removing the impurities (Fe(3+), Ca(2+), Mg(2+), S(4+), and P(3+)). Highly dispersed Al(OH)(3) with high S(BET) is obtained at pH = 6. The peaks of -CH(2)- vibration and the C1s peaks (binding energies of 284.6 eV) imply that polyethylene glycol 1000 (PEG-1000) is chemically adsorbed on the surface of Al(OH)(3) samples, which is propitious to reduce the hydrogen bonds between water molecules and surface -OH groups to prevent hard agglomeration. The stretching vibration peaks of [AlO(2)](-) and the Na1s peaks confirm that a trace of sodium aluminate (NaAl(OH)(4), Na(+)(H(2)O)(4)[Al(OH)(4)(-)], or the dehydrated monomers) is retained in the prepared Al(OH)(3). The main phase transformation for calcination (≤800 °C) of the SC-derived Al(OH)(3) is from amorphous Al(OH)(3) to amorphous A1(2)O(3). Here we highlight that production of Al(OH)(3) and SC from sludge provides the potential application in significant quantities that can revolutionize the handling of such kinds of harmful waste.

808 nm light triggered black TiO2 nanoparticles for killing of bladder cancer cells

The black TiO2 nanoparticles are synthesized via a facile calcination method combined with an in-situ controllable solid-state reaction approach. The results indicate that the photocatalyst with a narrow band gap of ~2.32 eV extends the photoresponse to visible light and near infrared region. And thus more reactive oxygen species can be obtained to induce the cell-killing under 808 nm light triggering. The as-obtained black TiO2 nanoparticles exhibiting low toxicity, good biocompatibility and high anticancer effect in vitro, is demonstrated as efficient photosensitizers for phototherapy to kill the bladder cancer cells. These findings suggest that the facile synthetic black TiO2 nanomaterials will have broad application in biomedicine.

Plasmon Ag decorated 3D urchinlike N-TiO 2−x for enhanced visible-light-driven photocatalytic performance

Plasmon Ag decorated 3D urchinlike N-TiO2-x photocatalysts are successfully synthesized by a facile hydrothermal treatment (180 °C) and combined with a photo-deposition approach, followed by a reduction treatment. The results show that the resultant Ag/N-TiO2-x sample possesses a three-dimensional (3D) urchinlike nanostructure with high crystallinity of anatase. Meanwhile, it exhibits the narrow optical band gap (Eg ∼ 2.61 eV) and the excellent visible-light-driven photocatalytic performance. Moreover, the hydrogen generation rate and photocatalytic degradation rate of phenol are up to 186.2 μmol h-1 g-1 and 97.7% under visible light irradiation, which are about 4.2 and 5.4 folds greater than that of N-TiO2. The mechanism of photocatalytic process is also proposed, and the enhanced photocatalytic property is mainly due to the synergistic reaction of the Ti3+ and N codoping, which narrows the band gap and favors the utilization of visible light, and the plasmon effect of Ag nanoparticles and unique 3D urchinlike architecture, which are propitious to the separation and transmission of photogenerated carriers.

Synergistic effect of surface plasmon resonance, Ti3+ and oxygen vacancy defects on Ag/MoS2/TiO2-x ternary heterojunctions with enhancing photothermal catalysis for low-temperature wastewater degradation

Ag/MoS2/TiO2-x ternary heterojunctions are fabricated through hydrothermal and photo-deposition process combine with in-situ solid-state chemical reduction approach. The prepared materials are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence, and X-ray photoelectron spectroscopy. The results show that the ternary heterojunctions doped with Ti3+ are formed, meanwhile, Ag nanoparticle and MoS2 nanosheets are anchored on surface of TiO2 nanobelts simultaneously. The photocatalytic degradation ratio of Bisphenol A in low temperature water and hydrogen production rate for Ag/MoS2/TiO2-x are up to 96.7% and ∼1.98 mmol h-1 g-1, respectively, which are several times higher than that of pristine TiO2. Furthermore, the photothermal performance of Ag/MoS2/TiO2-x is also unexpected. The excellent photocatalytic activity and photothermal performance can be ascribed to the synergistic effect of the formation of heterojunctions, Ti3+ and surface oxygen vacancies defects and surface plasmon resonance of Ag nanoparticles, which extend the photoresponse to visible-infrared light region and favor the spatial separation of photogenerated charge carriers.

C,N co-doped porous TiO2 hollow sphere visible light photocatalysts for efficient removal of highly toxic phenolic pollutants

Herein, C,N co-doped porous TiO2 hollow sphere visible light photocatalysts were fabricated using biocompatible N-lauroyl-l-glutamic acid as a doped precursor and soft-template by a mild and facile self-assembly soft-template method, followed by calcination at 550 °C in air. The structure, morphology, and surface elemental composition were characterized in detail by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results show that the prepared TiO2 photocatalysts have a porous hollow sphere structure and are co-doped with C and N. The visible-light-driven photocatalytic degradation rates of phenol and 2-chlorophenol are ∼92 and 90%, respectively. The photocatalytic reaction rate constants of phenol and dichlorophen on HPT550 porous TiO2 hollow spheres were about ∼4 and ∼2 times higher than those on P25, respectively. This enhancement is because the C,N co-doped porous TiO2 hollow spheres not only extend the photoresponse to the visible light region as C,N co-doping narrows the bandgap (2.7 eV), but also expose a large number of surface active sites that favor visible-light-driven photocatalysis. Moreover, the porous hollow structure favors multiple reflections of photons in the interior, increasing the utilization ratio of light. It is worth to pay more efforts to the development of visible light photocatalysts and further promote their practical application.