High photocatalytic degradation activity of polyethylene containing polyacrylamide grafted TiO2

A novel photocatalytic polyacrylamide grafted TiO₂ (PAM-g-TiO₂) nanocomposite was prepared and embedded into a low density polyethylene (LDPE) plastic. Photocatalytic degradation of the LDPE/PAM-g-TiO₂ composite film was carried out under ambient conditions under ultraviolet light irradiation. The properties of composite film were compared with those of the pure LDPE film by measuring the changes in weight loss, carbonyl index, molecular weight, tensile strength and elongation at break. PAM-g-TiO₂ embedded LDPE showed highly enhanced photocatalytic degradation. Irradiating the LDPE/PAM-g-TiO₂ composite film for 520 h under UV light reduced its weight by 39.85% and average molecular weight (M_w) by 94.60%, while that of pure LDPE film was only 1.03% and 69.59%, respectively. The addition of PAM-g-TiO₂ brought about the good dispersion of TiO₂ in LDPE matrix and improved the hydrophilicity of composite film, which were able to facilitate the degradation of LDPE. The photocatalytic degradation mechanism of the films is briefly discussed.     

Visible-light responsive dye-modified TiO2 photocatalyst

A series of dye-modified TiO₂ photocatalysts were synthesized using dye Chrysoidine G (CG), tolylene-2,4-diisocyanate (TDI), and commercial TiO₂ (Degussa P25) as starting materials. TDI was used as a bridging molecule whose two -NCO groups reacted with Ti-OH of TiO₂ and -NH₂ groups of CG, respectively. As a result, special organic complexes were formed on the TiO₂ surface via stable π-conjugated chemical bonds between TiO₂ and dye molecules, confirmed by FT-IR, XPS, and UV-vis spectra. Due to the existence of π-conjugated surface organic complexes, the as-synthesized photocatalysts showed a great improvement in visible absorption (400-550 nm). Methylene blue, as a photodegradation target, was used to evaluate the photocatalytic performance, and the dye-modified TiO₂ exhibited much better activity under the visible light irradiation than bare TiO₂.     

TiO2 nanoparticles incorporated with CuInS2 clusters: preparation and photocatalytic activity for degradation of 4-nitrophenol

TiO₂ nanoparticles incorporated with CuInS₂ clusters were prepared in a solvothermal process and characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersion X-ray analysis (EDX). Compared with pure TiO₂ nanoparticles, the TiO₂ nanoparticles incorporated with CuInS₂ clusters display higher photocatalytic activity with 99.9% of degradation ratio of 4-nitrophenol after 2 h irradiation. In order to investigate the effect of the CuInS₂ clusters on the photocatalytic activity of TiO₂ nanoparticles, diffuse reflectance UV–Vis spectra (DRS), photoluminescence (PL) spectra, and photocurrent action spectra were measured. The results indicate that the enhanced photocatalytic activity is probably due to the interface between TiO₂ and CuInS₂ as a trap of the photogenerated electrons to decrease the recombination of electrons and holes.     

Kinetic study on degradation of gaseous acetone over thin-film TiO2 photocatalyst in a continuous flow system

The effects of mixing condition by baffles, inlet concentration and face velocity on the photocatalytic degradation (PCD) of gaseous acetone over thin-film TiO₂ have been examined in a continuous flow system. The PCD rate increased upon installing baffles at a low inlet concentration and a high face velocity.     

Preparation and photocatalytic degradability of TiO2/polyacrylamide composite

Based on the unique absorbent characters and three-dimensional network structure of polyacrylamide (PAM) superabsorbent polymer, a photocatalytic degradable TiO₂/PAM composite was synthesized by an aqueous solution polymerization method with N,N′-methylene bisacrylamide as crosslinker, potassium peroxydisulfate as initiator, acrylamide as monomer, and TiO₂ (P-25) as functional filler. The photocatalytic degradability of the composite was evaluated using methyl orange as photodegradation target, and the recovery and reproducibility of the composite was investigated. It was found that TiO₂/PAM composite had a good photocatalytic degradability, the composite also possessed a good reproducibility of photocatalytic degradability, which is possible to be used in practical process.     

不同氮源溶剂热合成N-TiO2纳米颗粒及其光催化降解气相苯（英文）

采用三种不同的氮源溶剂热合成了锐钛矿-板钛矿混晶的N-TiO2催化剂.采用X射线衍射、N2吸附-脱附、X射线光电子能谱和透射电子显微镜等手段对催化剂进行了表征.重点研究了不同氮源对催化剂的相组成、晶粒尺寸、微观结构以及比表面积的影响.采用紫外光降解气相苯测试了合成材料的催化活性.结果表明,以水合肼为氮源合成的N-TiO2表现出最优的光催化活性,其活性明显高于P25,且能够循环使用15次以上.采用气相色谱-质谱技术分析了光降解过程的中间产物,基于此提出了相应的降解机理.     

Structural characterization and photocatalytic activity of hollow binary ZrO2/TiO2 oxide fibers

The formation of hollow binary ZrO₂/TiO₂ oxide fibers using mixed precursor solutions was achieved by activated carbon fibers templating technique combined with solvothermal process. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N₂ adsorption, X-ray photoelectron spectroscopy (XPS), UV-vis, and infrared (IR) spectroscopy. The binary oxide system shows the anatase-type TiO₂ and tetragonal phase of ZrO₂, and the introduction of ZrO₂ notably inhibits the growth of TiO₂ nanocrystallites. Although calcined at 575 °C, all hollow ZrO₂/TiO₂ fibers exhibit higher surface areas (>113 m²/g) than pure TiO₂ hollow fibers. The Pyridine adsorption on ZrO₂/TiO₂ sample indicates the presence of stronger surface acid sites. Such properties bring about that the binary oxide system possesses higher efficiency and durable activity stability for photodegradation of gaseous ethylene and trichloromethane than P25 TiO₂. In addition, the macroscopic felt form for the resulting materials is more beneficial for practical applications than traditional catalysts forms.     

TiO2/CuS异质结的制备及光催化降解染料废水的研究

以原位沉淀法和水热法混合的合成手段,制备了TiO_2/CuS异质结光催化剂。这种异质结改善了单一TiO_2半导体光催化剂的缺陷,明显提高了太阳光下光催化降解甲基橙的效率。TiO_2与CuS之间形成的异质结结构和合适的能带结构能够扩展材料对太阳光谱的响应范围并且很好地收集和传输光诱导载流子,从而提高了载流子的分离效率,最终使半导体的光催化活性明显增强。结果表明,太阳光照射25min后,相比于TiO_2/MnS、TiO_2/CdS和TiO_2/ZnS异质结,TiO_2/CuS异质结(TiO_2和CuS的摩尔比为3∶1)对甲基橙的降解效果最佳,降解效率能达到97.3%。为提高半导体的光催化活性提供了一条可行的路径。     

TiO2/carbon nanotube hybrid nanostructures: Solvothermal synthesis and their visible light photocatalytic activity

MWCNT/TiO₂ hybrid nanostructures were prepared via solvothermal synthesis and sol-gel method with benzyl alcohol as a surfactant. As-prepared hybrid materials were characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectra and X-ray photoelectron spectroscopy. The results showed that MWCNTs were uniformly decorated with anatase nanocrystals in solvothermal condition, but MWCNTs were embedded in a majority of TiO₂ nanoparticles by sol-gel method. When the weight ratio of MWCNTs to TiO₂ was 20%, MWCNT/TiO₂ hybrid nanostructures prepared by solvothermal synthesis exhibited higher visible-light-driven photocatalytic activity than that prepared by sol-gel method. Post-annealing of MWCNT/TiO₂ nanostructures at 400 °C resulted in the formation of the carbonaceous Ti-C bonds on the interface between TiO₂ and MWCNTs, which enhanced the photoabsorbance of the hybrid materials in the visible light region and improved the visible-light degradation efficiency of methylene blue.     

Photocatalytic efficiency of TiO2/poly[acrylamide-co-(acrylic acid)] composite for textile dye degradation

A novel photocatalytically degradable TiO₂/poly[acrylamide-co-(acrylic acid)] composite hydrogel (TiO₂/poly[AAm-co-AAc]) was synthesized by polymerization in an aqueous solution with N,N’-methylenebisacrylamide as the crosslinker and ammonium persulphate and TEMED as the initiator pair. The combined and separate effects of photodegradation and adsorption processes for dye removal were evaluated using methylene blue (MB) as the model dye for a photodegradation target, and compared with those of the neat poly[AAm-co-AAc], and a commercially available TiO₂ photocatalyst (Degussa P-25). Without photodegradation (i.e. in the dark), the TiO₂/poly[AAm-co-AAc] composite adsorbed up to 85% of the MB from a 5 mg L⁻¹ MB solution in 15 min compared to only 10% for the pristine TiO₂. The reproducibility in photodegradation of the reused poly[AAm-co-AAc] composite was also investigated, where poly[AAm-co-AAc] was found to be photocatalytically degraded under UV irradiation. Therefore, the TiO₂/poly[AAm-co-AAc] composite hydrogel is a good dye adsorber with self-photodegradability and it also can easily be separated from the reaction by simple filtration. With these properties, the TiO₂/poly[AAm-co-AAc] hydrogel can be called a green polymer for use in the photodegradation-adsorption process for the abatement of various pollutants.     

Synthesis and photocatalytic applications of Ag/TiO2-nanotubes

TiO₂- and Ag/TiO₂-nanotubes (NTs) were synthesized by hydrothermal methods and microwave-assisted preparation, respectively. Scanning electron microscopy, high resolution transmission electron microscopy, Brunauer-Emmett-Teller particle surface area measurement and X-ray diffraction were used to characterize the nanotubes. Rutile TiO₂-NTs with Na₂Ti₅O₁₁ crystallinity had a length range of 200-400 nm and diameters of 10-20 nm. TiO₂- and Ag/TiO₂-NTs with a 0.4% deposition of Ag had high surface areas of 270 and 169 m² g⁻¹, respectively. The evaluation of photocatalytic activity showed that Ag/TiO₂-NTs displayed higher photocatalytic activity than pure TiO₂-NTs and a 60.91% degradation of Rhodamine-B with 0.8% deposition of Ag species. Also 60% of Rhodamine-6G was physisorbed and 40% chemisorbed on the surface of TiO₂-NTs. In addition, the photocatalytic degradations of organochlorine pesticides taking α-hexachlorobenzene (BHC) and dicofol as typical examples, were compared using Ag/TiO₂-NTs, and found that their degradations rates were all higher than those obtained from commercial TiO₂.     

Preparation of a highly active nanocrystalline TiO2 photocatalyst from titanium oxo cluster precursor

Nanocrystalline TiO₂ (sample S1) was prepared from a titanium oxo cluster (Ti₇O₄(OEt)₂₀) precursor via a sol-gel route. This photocatalyst showed a higher photocatalytic activity than the TiO₂ (sample S2) obtained from titanium tetraisopropoxide. The samples were characterized by thermal analysis (TGA/DSC), X-ray diffraction, micro-Raman spectroscopy, transmission electron microscopy, N₂ adsorption (BET surface area), infrared absorption spectroscopy (FT-IR) and X-ray photoelectron spectroscopy. The characterization results show that both samples are anatase nanocrystals with particle sizes of about 12 nm, but the more photocatalytically active sample S1 has more surface hydroxyl groups and larger surface area and pore volume than sample S2.     

Fabrication and photocatalytic activity of high-efficiency visible-light-responsive photocatalyst ZnTe/TiO2 nanotube arrays

A new ZnTe modified TiO₂ nanotube (NT) array catalyst was prepared by pulse potential electrodeposition of ZnTe nanoparticles (NPs) onto TiO₂ NT arrays, and its application for photocatalytic degradation of anthracene-9-carboxylic acid (9-AnCOOH) was investigated. The even distribution of ZnTe NPs was well-proportionately grown on the top surface of the TiO₂ NT while without clogging the tube entrances. Compared with the unmodified TiO₂ NT, the ZnTe modified TiO₂ NT (ZnTe/TiO₂ NT) showed significantly enhanced photocatalytic activity towards 9-AnCOOH under simulated solar light. After 70 min of irradiation, 9-AnCOOH was degraded with the removal ratio of 45% on the bare TiO₂ NT, much lower than 80%, 90%, and 100% on the ZnTe/TiO₂ NT with the ZnTe NPs prepared under the pulsed “on” potentials of −0.8, −1.0, and −2.0 V, respectively. The increased photodegradation efficiency mainly results from the improved photocurrent density as results of enhanced visible-light absorption and decreased hole-electron recombination due to the presence of narrow-band-gap p-type semiconductor ZnTe.     

Preparation and photocatalytic activity of high-efficiency visible-light-responsive photocatalyst SnSx/TiO2

Visible-light-responsive composite photocatalysts SnS₂/TiO₂ and SnS/TiO₂ with different mass ratios were prepared by in-situ synthesis technology in solution with commercial TiO₂. The junction-based materials SnS_x (x=1, 2)/TiO₂ were found to have high visible-light photocatalytic performance and possess much better activity than the single-phase SnS_x or TiO₂. The greatly enhanced photocatalytic activity of the SnS_x/TiO₂ composites was mainly attributed to the matching band potentials and efficient charge transfer and separation at the tight-bonding interface between SnS_x and TiO₂. The fact was confirmed by the comparison of photocatalytic activities of the SnS₂/TiO₂ samples prepared by physical mixing method and in-situ synthesis technique.     

ZnFe2O4/Ag/TiO2复合材料的制备及其光催化性能

以硝酸银、钛酸四丁酯、无水氯化锌、六水氯化铁为原料,采用溶胶-凝胶法与溶剂热相结合的方法制备了ZnFe₂O₄/Ag/TiO₂复合材料,通过扫描电子显微镜、能谱分析仪、X射线粉末衍射仪、X射线光电子能谱仪、振动样品磁强计、紫外可见分光光度计对样品进行表征及测试。结果表明： ZnFe₂O₄/Ag/TiO₂-10具有最佳的光催化效果,在紫外和可见光下对染料的降解率都能达到90%以上,具有优异的紫外可见光光催化活性。ZnFe₂O₄/Ag/TiO₂具有独特的磁性,能在外部磁场作用下进行回收利用,这使其在实际应用中成为可能。通过磁分离技术重复回收利用5次后仍然保持优良的光催化性能,说明ZnFe₂O₄/Ag/TiO₂-10具有优异的磁性及较高的光催化循环稳定性。     

ZnFe2O4/Ag/TiO2复合材料的制备及其光催化性能

以硝酸银、钛酸四丁酯、无水氯化锌、六水氯化铁为原料,采用溶胶-凝胶法与溶剂热相结合的方法制备了ZnFe₂O₄/Ag/TiO₂复合材料,通过扫描电子显微镜、能谱分析仪、X射线粉末衍射仪、X射线光电子能谱仪、振动样品磁强计、紫外可见分光光度计对样品进行表征及测试。结果表明：ZnFe₂O₄/Ag/TiO₂-10具有最佳的光催化效果,在紫外和可见光下对染料的降解率都能达到90%以上,具有优异的紫外可见光光催化活性。ZnFe₂O₄/Ag/TiO₂具有独特的磁性,能在外部磁场作用下进行回收利用,这使其在实际应用中成为可能。通过磁分离技术重复回收利用5次后仍然保持优良的光催化性能,说明ZnFe₂O₄/Ag/TiO₂-10具有优异的磁性及较高的光催化循环稳定性。     

Hydrothermal synthesis of mesostructured nanocrystalline TiO2 in an ionic liquid–water mixture and its photocatalytic performance

Anatase mesostructured TiO₂ nanocrystalline was prepared in a mixture of 1-butyl-3-methyl-imidazolium tetrafluoroborate (BMIM⁺BF₄⁻) ionic liquid and water by a low temperature hydrothermal method. The obtained materials were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and N₂ adsorption–desorption. The existence of BMIM⁺BF₄⁻ enhanced the polycondensation and crystallization rate, which encouraged the formation of anatase crystal. The TiO₂ particles were thermally very stable and thus resistant to anatase-rutile phase transformation during calcination at high temperatures. The anatase TiO₂ showed high photocatalytic activity in the degradation of p-chlorophenol than that of the commercially available TiO₂, Degussa P25. After 2 h reaction under the UV-irradiation of 250 W, the removing rate of p-chlorophenol was up to 96.3%.     

Synthesis of nanosized TiO2/SiO2 catalysts by the ultrasonic microemulsion method and their photocatalytic activity

Nanosized TiO₂/SiO₂ catalysts prepared by hydrolysis of titanium n-butoxide in microemulsion showed enhanced photocatalytic activity. In the presence of catalyst ME-2 and after 90 min irradiation by UV light, methylene blue was completely converted evidenced by the absence of its absorption band in the UV-Vis spectra. This catalyst demonstrated much better degradation ability than P-25 and naked TiO₂.     

TiO2/Cu2O/Pt复合空心微球的制备及其光催化性能

以锐钛矿相TiO₂溶胶为基底,采用沉淀法和液相沉积法制备了TiO₂/Cu₂O/Pt复合空心微球,通过改变n_Ti⁴⁺∶ n_Cu²⁺和H₂PtCl₆·6 H₂O溶液的加入量对TiO₂的形貌和结构进行调控,采用不同的方法对不同样品的物相及结构、微观形貌和光学性能进行了对比分析。分析结果表明,复合材料中Pt与Cu₂O的引入产生协同效应,不仅在一定程度上阻止了电子-空穴的复合,还降低了禁带宽度,在可见光区域光吸收明显增强。与TiO₂、Cu₂O和TiO₂/Cu₂O光催化剂相比较,TiO₂/Cu₂O/Pt降解有机污染物的能力显著增强,首次光照120 min可降解93%的甲基橙(MO)溶液,4次循环后降解率为71%,具有良好的光催化稳定性能。     

TiO2/Cu2O/Pt复合空心微球的制备及其光催化性能

以锐钛矿相TiO₂溶胶为基底,采用沉淀法和液相沉积法制备了TiO₂/Cu₂O/Pt复合空心微球,通过改变n₍Ti⁴⁺)∶n_Cu2+和H₂Pt Cl₆·6H₂O溶液的加入量对TiO₂的形貌和结构进行调控,采用不同的方法对不同样品的物相及结构、微观形貌和光学性能进行了对比分析。分析结果表明,复合材料中Pt与Cu₂O的引入产生协同效应,不仅在一定程度上阻止了电子-空穴的复合,还降低了禁带宽度,在可见光区域光吸收明显增强。与TiO₂、Cu₂O和TiO₂/Cu₂O光催化剂相比较,TiO₂/Cu₂O/Pt降解有机污染物的能力显著增强,首次光照120 min可降解93%的甲基橙(MO)溶液,4次循环后降解率为71%,具有良好的光催化...