MoS_2负载量对MoS_2/TiO_2光催化降解苯酚效率的影响及其作用机理研究

通过水解法制备TiO_2纳米颗粒,与经过超声处理后的MoS_2片层纳米材料复合制备MoS_2/TiO_2纳米催化剂,考察不同MoS_2负载量对其光催化降解苯酚效率及路径的影响。XRD、SEM、EDS、FT-IR和UV-vis DRS等表征结果表明,复合催化剂主要由锐钛矿型TiO_2和MoS_2组成;剥离后的MoS_2呈现薄片层状结构,均匀地分散在TiO_2纳米颗粒当中。光催化降解苯酚性能测试结果显示,对于MoS_2/TiO_2催化剂,MoS_2负载量的提高有利于光催化降解苯酚效率的提高;当MoS_2负载量为27%时,复合M o S2/TiO_2纳米颗粒的光催化性能最佳,反应80 min后可将苯酚完全降解。通过对苯酚降解过程中生成中间产物跟踪发现,MoS_2负载量的提高有利于促进中间产物苯醌、对苯二酚以及邻苯二酚的生成,进而提升了MoS_2/TiO_2复合材料的光催化性能。     

半导体复合CdS/TiO2催化剂改性及冷冻-光催化组合方法应用的初步研究

采用溶胶-凝胶法制备多孔氧化钛,并耦合CdS,制备多孔耦合CdS/TiO₂催化剂.煅烧温度为700℃,CdS掺杂比例为3%时,催化剂性能较优.以太阳光为光源,考查了溴氨酸初始浓度对其降解效果的影响,并采用冷冻-光催化组合方法对较高浓度的溴氨酸废水的处理进行了初步研究.浓度为500 mg/L的溴氨酸模拟废水(其中氯化钠质量浓度为500 mg/L)经冷冻后,当成冰率为70%时,体系中冰层的Na⁺含量、总有机碳(TOC)和吸光度分别由209.88 mg/L,208.90 mg/L和8.120降至19.06 mg/L,24.80 mg/L和0.638.使用多孔耦合催化剂对该冰层融水光降解,光照6 h,褪色率和TOC去除率分别达到100%和87.04%.     

Photocatalytic degradation of hydrocarbons by bentonite and TiO2 in aqueous suspensions containing surfactants

Organic substances (toluene, asphaltene dissolved in toluene) poorly soluble in water were solubilized by sodium dodecylsulfate (SDS) and the organic pollutants were mineralized together with the surfactants in diluted TiO₂ suspension by UV light. In concentrated aqueous suspension, crude oil was photodegraded on the surface of Na-bentonite and the photocatalyst TiO₂. Experiments have been carried out with Na-bentonite contaminated with crude oil mixed in a ratio of 1:1 with TiO₂ as well. The photooxidation processes were followed by total organic carbon content (TOC) and diffuse reflection infrared spectroscopy (DRIFT) measurements.     

C/Cr2O3/TiO2复合材料的制备及其光催化性能研究

本文以制革含铬革屑为原材料,基于矿物鞣剂复鞣的原理,将Ti(IV)均匀、稳定地负载到含铬革屑上,在氮气氛围下,经高温热解制备得到C/Cr₂O₃/TiO₂光催化剂,并研究了其对四环素(TC)的光催化降解效果及机理。结果表明,C/Cr₂O₃/TiO₂光催化剂具有明显的介孔结构,比表面积较大,为277.47 m²·g^-1,Cr₂O₃和TiO₂已实现复合并负载在生物炭(C)上。通过光催化降解发现,在模拟自然光照下,当催化剂用量为0.04 g,TC初始浓度为50 mg·L^-1,溶液pH为2时,TC的去除率可高达99.99%。结合自由基捕获实验发现,C/Cr₂O₃/TiO₂光催化剂对TC的降解作用主要依靠反应体系中产生的大量·O₂^-,·OH和h⁺。     

Ti/TiO_2纳米管阵列/PbO_2-Pr电极制备及在电氧化有机废水中应用

以二氧化钛纳米管阵列(TiO_2NTs)为基体,利用脉冲电沉积的方法将Pr掺杂的PbO_2修饰到TiO_2NTs管中,制备出新型电极材料Ti/TiO_2NTs/nanoPbO_2-Pr用来降解有机废水。通过循环伏安测试(CV)和线性伏安法(LSV)等手段对电极性能进行评估,研究表明,新型电极材料Ti/TiO_2NTs/nanoPbO_2-Pr具有高的电催化活性。利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线光电子能谱(XPS)等对其进行表面形貌、晶形结构和元素组成进行研究。结果表明,通过脉冲电沉积成功将Pr-PbO_2沉积到TiO_2纳米管中,其中元素Pr是以Pr_2O_3形式存在。亚甲基蓝降解实验证明,Ti/TiO_2NTs/nanoPbO_2-Pr电极降解120min后亚甲基蓝的去除率高达99.8%。     

Stabilization mechanism of TiO2 on flexible fluorocarbon films as a functional photocatalyst

The repetitive discoloration kinetics of the azo-dye Methyl Orange (taken as a model organic compound) was followed under solar simulated radiation (90 mW/cm²) to assess the performance of the TiO₂/Tedlar^® composite photocatalyst. The influence of solution parameters on the photo-discoloration process: pH, dye concentration, applied light intensity and concentration of H₂O₂ were systematically investigated. During the photocatalysis a modification occurs in the TiO₂/Tedlar^® composite due to the TiO₂ interaction with the Tedlar^® film. Physical insight is given for the stabilization mechanism of the TiO₂ particles in the Tedlar matrix based on the data obtained by X-ray photoelectron spectroscopy (XPS). The F 1s peak of the Tedlar film indicates that the TiO₂ is loaded on the Tedlar fluoro-groups. The loading of TiO₂ on the 75 μm thick Tedlar^® film was 0.9% (w/w) as determined by atomic absorption spectrophotometry (AAS). Attenuated total reflection infrared spectroscopy (ATRIR) shows no formation of additional bands within the photodiscoloration reaction. This shows that an efficient catalysis taking place on the TiO₂/Tedlar^® surface. The rugosity (mean square roughness, rms) of the TiO₂/Tedlar^® film was determined by atomic force microscopy (AFM) to be 19.7 nm. This value remained constant during long-term operation. Transmission electron microscopy (TEM) reports the thickness and coverage of TiO₂ Degussa P-25 on the Tedlar^® surface before and after photocatalysis.     

Synthesis of Gd-N Codoped Porous TiO2 Photocatalyst and Its Enhanced Photocatalytic Activities

Visible-light-active Gd-N codoped porous TiO₂(Gd-N-TiO₂) photocatalyst was fabricated by an evapora-tion-induced self-assembly route using surfactants as structure-directed agents. As-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy(TEM), X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller(BET) method, and ultraviolet-visible absorption spectroscopy. The results indicated that synergistic reaction occurred when codoping with Gd³⁺ and N, which enhanced the light absorption properties of TiO₂. Irregular worm-like particles with wide interparticle spaces were clearly observed by TEM. The average particle size of Gd-N-TiO₂ decreased to ca. 8 nm because co-doping inhibited the particles growth significantly. Thus, the specific surface area of Gd-N-TiO₂(198.7 m²/g) was higher than that of Degussa P25 TiO₂(50 m²/g). Gd-N-TiO₂ exhibited a high photocatalytic activity toward methyl orange degradation under UV-Vis or visible-light irradiation. The Gd-N-TiO₂ catalyst also presented a stable performance without losing activity after four successive photocatalytic experiments. The facile synthesis and excellent activity of Gd-N-TiO₂ indicated its great potential as industrial catalysts for wastewater treatment.     

罗丹明B在TiO2薄膜和P-25涂层催化下光反应的比较

半导体光催化剂尤其是TiO₂由于表面的光生空穴具有很强的氧化能力^[1-2],能够完全降解有机物,在环境治理方面具有潜在的应用前景,因而日益引起人们的关注.目前,利用胶体溶液和颗粒悬浮体系光催化降解有机污染物的研究已经开展得十分广泛^[3-5].但是,从实用的角度来考虑,这一体系存在许多缺点,如反应后催化剂难于分离,颗粒不适宜作循环体系的处理等等,因此催化剂的固定日益迫切.为解决这一问题,近来已经有许多人在固定粉末催化剂以及制备催化剂薄膜方面^[6-8]进行了探索和尝试,但尚未得到理想的结果.因而发展高效固定化的催化剂仍然是极为重要的,同时对于薄膜催化机理的深入探讨也有利于在制备过程中有目的地提高膜的催化活性.     

The photocatalytic activity of TiO2 foam and surface modified binary oxide titania nanoparticles

Surface modified titania dioxide composite nanoparticles prepared by hydrogen reduction reaction and a mesoporous TiO₂ foam made from a surface modifier and a long chain organic surfactant were characterized by diffractive, spectroscopic and microscopic techniques and studied for their catalytic activity towards the decomposition of an industrial water pollutant, methyl orange. The surface deposition of ruthenium and silicon particles improved the photocatalytic activity of the composite particles resulting in a faster decomposition of the methyl orange compared to commercial TiO₂ alone. Modification of TiO₂ with RuO₂ only offered a marginal benefit over TiO₂ while the incorporation of RuO₂ and SiO₂ into TiO₂ resulted in a marked increase in the rate constant and catalytic activity. These results are consistent with the enhanced surface properties of the composite materials resulting from the modification of TiO₂ with RuO₂ and SiO_2. This surface enhancement effects appear synergetic to the charge separation process and hence the photocatalytic results are explained on the basis of a mechanism involving efficient charge transfer across the interfaces of the composites involving photogenerated electron–hole pairs. Results obtained in this study show that the percentage degradation after 1 h of illumination was 47.15% for TiO₂ foam, 75.5 and 106.4%, respectively, for TiO₂/RuO₂ (SiO₂ 5%, w/w) and TiO₂/RuO₂(SiO₂ 10%, w/w) and 34.15% for commercial TiO₂.     

LaNiO3/TiO2纳米管阵列的电化学制备及其光催化性能

利用脉冲电沉积与高温退火相结合的方法制备了镍酸镧(LaNiO₃)纳米颗粒负载的二氧化钛(TiO₂)纳米管阵列. 修饰于TiO₂纳米管阵列上的LaNiO₃纳米颗粒粒径小（< 10 nm）、分布均匀、负载量可控,一些LaNiO₃纳米颗粒沉积于TiO₂纳米管内. 紫外可见吸收光谱显示,LaNiO₃/TiO₂纳米管阵列的吸收带边较TiO₂纳米管阵列明显红移,可见光吸收明显增强. 可见光下光催化降解罗丹明B（RhB）的结果表明,脉冲循环沉积500次制得的LaNiO₃/TiO₂纳米管阵列的光催化活性最佳,其对RhB光催化降解速率是TiO₂纳米管阵列的3.5倍,并且表现出极好的光催化稳定性.     

Characterization and photocatalytic properties of silver and silver chloride doped TiO2 hollow nanoparticles

Using polystyrene（PSt） particles as template,PSt/TiO₂ composite particles with AgCl incorporation were prepared through hydrolysis of tetrabutyl titanate in the presence of AgNO₃ and NaCl.AgCl doped TiO₂ hollow particles were successfully prepared with the PSt/TiO₂ composite microspheres pretreated at 180℃followed by calcination.The morphology of PSt/TiO₂ particles and the crystal structures of the AgCl doped TiO₂ hollow particles were characterized.The photocatalytic activity of the doped TiO₂ hollow particles in degradation of Rhodamine B was tested under UV and visible lights and compared to that with Ag doped TiO₂ particles.The results showed that TiO₂ hollow particles,either doped with Ag or AgCl,demonstrated higher photocatalytic activity than the pure TiO₂ particles.This enhancement in photocatalytic activity was more significant with AgCl doped TiO₂ than that with Ag doped,and more distinct when the degradation was done under visible light than that under LTV light.     

一维TiO2锐钛矿/金红石异相结的制备及光催化降解甲醛性能

TiO₂异相结主要通过高温方法制备,所制备材料的形貌和组成较难控制,尤其是在较低温度下一步制备一维TiO₂异相结仍具有一定的挑战性。采用简单、方便的一步水热法,在较低温度下(180℃)制备了一维纳米TiO₂异相结材料。X射线衍射(XRD)和高分辨透射电镜(HRTEM)分析表明,制备的材料以一维金红石相TiO₂纳米棒(长度：(400±50) nm,直径：(60±5) nm)为基本结构,粒径分布均匀的锐钛矿相TiO₂纳米粒子(直径：(9.5±0.5) nm)高密度、单分散地负载在纳米棒上。通过控制水热反应时间成功调控了异相结中锐钛矿相TiO₂的含量(20%～50%),进而实现了其光催化降解HCHO性能的调控。实验结果表明,当锐钛矿相TiO₂的含量为33%时(TiO₂-24,水热时间24 h制备的样品),异相结光催化剂表现出最佳的HCHO降解性能：在低光强LED灯(波长为365 nm,光强为12.26 mW·cm     

Pd/TiO2 Nanospheres with Three-dimensional Hyperstructure for Enhanced Photodegradation of Organic Dye

Pd/TiO2 nanospheres assembled from nanorods with three-dimensional hyperstructure for enlianced photodegradation of organic dye was prepared by a sample solvothemial method. Further, it was used for degradation of methyl orange(MO) under the illumination of visible-light(simulated).The results show that Pd/TiO2 with 2%(mass fraction) Pd exhibits the noticeable activity in photodegrading of MO.The detailed analysis shows that this enhancement is attributed to the reduction of the rate of electron-hole recombination and surface plasmon resonance of Pd. The high activity and good stability of the obtained Pd/TiO2 nano spheres make it a promising photocatalyst for solving the environmental pollution problems.     

Synthesis of nanosized TiO2 particles in reverse micelle systems and their photocatalytic activity for degradation of toluene in gas phase

Nanosized pure TiO₂ particles with high crystallinity and large surface area were prepared by hydrolysis of tetrabutyl titanate in water/Triton X-100/isooctane reverse micelle solutions as reaction media followed by hydrothermal treatment to improve crystallinity. The prepared TiO₂ nanoparticles were characterized by XRD, BET, TGA, FT-IR and TEM. The size of ultrafine particles was controlled by changing the water content of the reverse micelle solution. The TiO₂ particles showed monodispersity, large surface area and high degrees of crystallinity and thermostability. The photocatalytic activity of the TiO₂ particles was evaluated by decomposition of toluene in the gas phase. The activity of the TiO₂ nanoparticles was higher than that of commercially available anatase fine particles, such as ST-01, which is one of the most active photocatalysts for degradation of organic compounds in the gas phase.     

TiO2/Bi2O3纳米复合体的制备及可见光催化产氢性能

首先采用相分离的水解-溶剂热法制备了Bi₂O₃纳米粒子,然后利用简单的湿化学法在Bi₂O₃表面负载不同比例的TiO₂纳米颗粒,进而得到TiO₂/Bi₂O₃纳米复合体。通过气氛调控的表面光电压谱(SPS)等测试表明,表面负载适量的TiO₂后能够提高Bi₂O₃光生电荷分离。可见光催化产氢和降解污染物测试结果进一步证明,表面负载适量的TiO₂后可显著提高其可见光催化活性,其中Ti/Bi摩尔比为7%时具有最高的光催化活性。这主要归因于TiO₂具有较为合适的导带能级位置,可以接收Bi₂O₃在可见光激发下所产生的高能级电子,从而抑制光生电子-空穴对复合,并且维持了高能级电子较高的还原能力。     

太阳光照射浮石负载二氧化钛降解氨氮废水

采用溶胶-凝胶法制备了Ti O_2,并使Ti O_2负载在浮石上制备Ti O_2/浮石光催化剂。用X射线荧光光谱(XRF)、电镜扫子显微描(SEM)和傅里叶红外光谱(FT-IR)表征浮石、Ti O_2及Ti O_2/浮石。在太阳光照射下,用Ti O_2/浮石处理模拟氨氮废水,以废水中氨氮降解率为标准,考察影响氨氮降解因素。结果表明,Ti O_2成功固定在浮石表面,负载率为3.71%;废水中氨氮降解率随太阳光照射时间、废水p H值、催化剂Ti O_2/浮石含量增加而增大。当初始氨氮浓度为500 mg/L、太阳照射180 min、废水p H=11、催化剂Ti O_2/浮石剂量为20 g/L时,氨氮降解率达82.0%,氨氮除去率86.8%,降解产物中未发现污染成分NO_2~-和NO_3~-产生。催化剂再生/催化3次,每次再生后氨氮降解率约下降10.0%。该方法快速、简单、低消耗和产生二次污染少,能有效地降解废水中的氨氮。     

Photocatalytic degradation and kinetics of Orange G using nano-sized Sn(IV)/TiO2/AC photocatalyst

Sn(IV) doped and nano-sized TiO₂ immobilized on active carbon (AC) (Sn(IV)/TiO₂/AC) were prepared by the sol–gel and dip-calcination method. An azo dye, Orange G (OG), was used as a model compound to study its photocatalytic activity in a fluidized bed photoreactor. The addition of Sn(IV) on TiO₂ could greatly improve the activity of TiO₂, and the optimal amount of tin was 2.5 at.%. The effects of calcination temperature, pH value, the initial hydrogen peroxide concentration ([H₂O₂]₀), the catalyst amount ([TiO₂]), the initial OG concentration ([dye]₀) and co-existing negative ions on the photocatalytic activity of Sn(IV)/TiO₂/AC were studied. The optimal conditions were as follows: pH 2.00, [H₂O₂]₀ = 1.5mL/L, [dye]₀ = 50 mg/L, [TiO₂] = 12.5 g/L, when the 300 W high pressure mercury light was used as the light source. Under these conditions, the degradation efficiency of OG reached 99.1% after 60 min reaction. The kinetics of the OG degradation was also analyzed. The results showed that the kinetics of this reaction fit the Langmiur–Hinshelwood kinetics model well and the absorption of OG on the Sn(IV)/TiO₂/AC surface was the controlling step in the whole degradation process. In addition, the catalyst, liquid and gas were separated effectively, and the integrative process of reaction and separation was achieved during the experiment.     

Dispersion properties of TiO2 nano-powder synthesized by homogeneous precipitation process at low temperatures

The dispersion stability of rutile TiO₂ powder with a unique nano-structure synthesized by homogeneous precipitation process at low temperatures (HPPLT) has been investigated with adding the various electrolytes in both pure aqueous and organic media. Zeta potential measurements have shown that the addition of electrolytes such as CsCl, CaCl₂, FeCl₃, and ZrCl₄ to aqueous and pure organic dispersion media leads to generally a charge reversal from negative to positive on the surface of TiO₂ particle. The electrostatic repulsive force acting on between TiO₂ particles dispersed in pure organic media was found to be significantly greater than that in aqueous media, which is closely related to the physical properties of the organic solvents, such as viscosities and dielectric constant. The surface potentials of TiO₂ particles have been greatly modified by the particulate properties, pH, dispersion medium, and valence of the ionic species, which governs the colloidal behavior of TiO₂ particles virtually.     

Enhanced Visible-light Photocatalytic Activity of g-C3N4/Nitrogen-doped Graphene Quantum Dots/TiO2 Ternary Heterojunctions for Ciprofloxacin Degradation with Narrow Band Gap and High Charge Carrier Mobility

Limited visible-light absorption and high recombination rate of photogenerated charges are two main drawbacks in g-C₃N₄-based photocatalysts. To solve these problems, g-C₃N₄/nitrogen-doped graphene quantum dots (NGQDs)/TiO₂ ternary heterojunctions were facilely prepared via a one-step calcining method. The morphology, structure, optical and electrochemical properties of g-C₃N₄/NGQDs/TiO₂ were characterized and explored. The optimal g-C₃N₄/NGQDs/TiO₂ composite exhibits enhanced photocatalytic degradation performance of ciprofloxacin (CIP) compared with the as-prepared g-C₃N₄, TiO₂(P25) and g-C₃N₄/TiO₂ heterojunction under visible light irradiation. The apparent rate constant of the composite is around 6.43, 4.03 and 2.30 times higher than those of g-C₃N₄, TiO₂ and g-C₃N₄/TiO₂, respectively. The enhanced photocatalytic efficiency should be mainly attributed to the improvement of light absorption and charge separation and transfer efficiency, originating from the narrow band gap and high charge carrier mobility. The active species trapping experiments results showed that the h⁺ and ^·O₂^- were the main active species in the degradation process. A possible photocatalytic reaction mechanism of the g-C₃N₄/NGQDs/TiO₂ composite for the enhanced degradation of CIP under visible light irradiation was also proposed.