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1.
Microwave-induced nitrogen-doped titanate nanotubes(NTNTs) were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), Fourier transform infrared spectroscopy(FT-IR), Zeta potential analysis,specific surface area(SBET), and UV-Visible spectroscopy. TEM results indicate that NTNTs retain a tubular structure with a crystalline multiwall and have a length of several hundred nanometers after nitrogen doping. XRD findings demonstrate that the crystalline structure of NTNTs was dominated by anatase, which is favored for photocatalytic application. The Ti-O-N linkage observed in the XPS N 1s spectrum is mainly responsible for narrowing the band gap and eventually enhancing the visible light photoactivity. FT-IR results demonstrated the existence of H3O+, which could be excited by photo-generated holes to form hydroxyl radicals and degrade environmental pollutants. After sintering at 350°C, the UV-Vis absorbance edges of NTNTs significantly shift to the visible-light region, which indicates N atom doping into the nanotubes. Photocatalytic degradation of Rhodamine B(RhB) via NTNTs show good efficiency, with pseudo first-order kinetic model rate constants of 3.7 × 10-3, 2.4 × 10-3and 8.0 × 10-4sec-1at pH 3, 7, and 11, respectively.  相似文献   

2.
To utilize visible light more effectively in photocatalytic reactions, a fly ash cenosphere (FAC)-supported CeO2-BiV04 (CeO2-BiVO4/FAC) composite photocatalyst was prepared by modified metalorganic decomposition and impregnation methods. The physical and photophysical properties of the composite have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and UV-Visible diffuse reflectance spectra. The XRD patterns exhibited characteristic diffraction peaks of both BiVO4 and Ce02 crystalline phases. The XPS results showed that Ce was present as both Ce4+ and Ce3+ oxidation states in Ce02 and dispersed on the surface of BiV04 to constitute a p-n heterojunction composite. The absorption threshold of the CeO2-BiVO4/FAC composite shifted to a longer wavelength in the UV-Vis absorption spectrum compared to the pure Ce02 and pure BiV04. The composites exhibited enhanced photocatalytic activity for Methylene Blue (MB) degradation under visible light irradiation. It was found that the 7.5 wt.% CeO2-BiVO4/FAC composite showed the highest photocatalytic activity for MB dye wastewater treatment.  相似文献   

3.
利用水热合成法制备了C_3N_4/BiOBr复合可见光催化剂,通过XRD、FT-IR、SEM、DRS、PL等手段对催化剂的物相组成和光化学性能进行了系统表征,利用对罗丹明B(RhB)的降解实验评价了催化剂在可见光照下的光催化降解活性和稳定性并通过ESR分析和自由基捕获实验探究了RhB的光催化降解机制.结果表明,水热合成法可成功制备结晶性能良好的C_3N_4/BiOBr复合可见光催化剂;C_3N_4的复合降低了BiOBr光催化剂的电子-空穴的复合,提高了光催化降解活性,其中15%C_3N_4/BiOBr的活性最佳,可见光照18 min后RhB的脱色率达100%,较纯BiOBr提高了1.5倍,且重复使用5次后仍具有较高的光催化降解活性;复合催化剂光催化降解RhB过程中参与降解的主要活性物种为空穴(h~+)和超氧自由基(·O_2~-),其中h~+影响更为显著.  相似文献   

4.
Visible light responsive N-F-codoped TiO2 photocatalysts exhibit a higher catalytic activity than N-doped TiO2 for the degradation of 4-chlorophenol due to the synergistic effect of nonmetal elements.  相似文献   

5.
Multi-walled carbon nanotubes (MWCNTs)/TiO2 composite photocatalysts with high photoactivity were prepared by sol-gel process and further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and UV-vis absorption spectra. Compared to pure TiO2, the combination of MWCNTs with titania could cause a significant absorption shift toward the visible region. The photocatalytic performances of the MWCNTs/TiO2 composite catalysts were evaluated for the decomposition of Reactive light yellow K-6G (K-6G) and Mordant black 7 (MB 7) azo dyes solution under solar light irradiation. The results showed that the addition of MWCNTs enhanced the adsorption and photocatalytic activity of TiO2 for the degradation of azo dyes K-6G and MB 7. The effect of MWCNTs content, catalyst dosage, pH, and initial dye concentration were examined as operational parameters. The kinetics of photocatalytic degradation of two dyes was found to follow a pseudo-first-order rate law. The photocatalyst was used for seven cycles with photocatalytic degradation efficiency still higher than 98%. A plausible mechanism is also proposed and discussed on the basis of experimental results.  相似文献   

6.
Cerium-doped SiO2/TiO2 nanostructured fibers were fabricated by electrospinning technology. The prepared fibers were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Using the fibers as catalysts, photocatalytic degradation of Methylene Blue (MB) aqueous solution was carried out under simulated sunlight. The 0.2% Ce doping proved to be the optimal concentration for the doping of TiO2/SiO2, compared to other Ce-doped molar concentrations. The 0.2% Ce-doped SiO2/TiO2 fibers exhibited higher photocatalytic activity than industrial Degussa P25 and the samples doped with only Ce or SiO2. The reasons for improving the photocatalytic activity were also discussed. Several operational parameters were studied, which showed that the photocatalytic efficiency of MB was influenced by parameters such as the initial dye concentration, the initial pH, inorganic anions, and so on. In addition, the influences of an electron acceptor and a radical scavenger suggested that OH was the dominant photooxidant during the photocatalytic process. The reuse evaluation of the fibers indicated that their photocatalytic activity had good stability.  相似文献   

7.
A nanoheterojunction composite photocatalyst Bi2O3/TiO2working under visible-light(λ 420 nm) was prepared by combining two semiconductors Bi2O3 and TiO2 varying the Bi2O3/TiO2molar ratio. Maleic acid was employed as an organic binder to unite Bi2O3 and TiO2 nanoparticles. The SEM, TEM, XRD and diffuse reflectance spectra were utilized to characterize the prepared Bi2O3/TiO2nanoheterojunction. The nanocomposite exhibited unusual high photocatalytic activity in decomposing 2-propanol in gas phase and phenol in aqueous phase and, evolution of CO2 under visible light irradiation while the end members exhibited low photocatalytic activity. The composite was optimized to 5 mol% Bi2O3/TiO2. The remarkable high photocatalytic efficiency originates from the unique relative energy band position of Bi2O3 and TiO2 as well as the absorption of visible light by Bi2O3.  相似文献   

8.
合成了一种新型含有稀土金属Er的上转换发光剂40CdF2·60BaF2·1.6Er2O3,此上转换发光剂在488 nm可见光的激发下,产生了5个波长均小于387 nm的上转换紫外光发射峰.采用超声波分散的方法制备出了上转换发光剂掺杂的纳米TiO2可见光光催化剂.利用X-射线衍射(XRD)及透射电镜(TEM)对催化剂进行了表征.以乙基紫染料为研究对象,研究了在(三基色灯下发出的)可见光的照射下该可见光光催化剂的催化降解性能,并与未掺杂的纳米TiO2粉末的催化性能进行了对比.结果表明,作为掺杂成分的上转换发光剂可有效地将可见光转化为紫外光并被纳米TiO2粉末吸收利用,在可见光照射12.0 h后乙基紫降解率达到了99.68%,大大高于未掺杂纳米TiO2时的降解率.  相似文献   

9.
分别制备了花状Bi2MoO6和片状Ni2P,采用研磨、水热及超声的方式将两种材料复合,考察了负载方式、负载率和溶液pH值对其可见光下降解亚甲基蓝(MB)的影响;利用XRD、XPS、FTIR、SEM、PL和UV-Vis等测试手段表征了样品的微观结构、形貌和光学性质;研究表明Ni2P作为助催化剂,可加速电子空穴对分离,显著提高Bi2MoO6的光催化活性,其中当Ni2P负载率为4%时,TOC去除率为64.28%,降解速率为纯Bi2MoO6的2倍,且将Ni2P/Bi2MoO6复合催化剂循环利用3次后,同实验条件下降解率为94%,证明复合催化剂稳定性好.  相似文献   

10.
利用简单的热聚合及原位沉淀法制备了一系列不同质量比(1%~10%)的Ag/P-g-C_3N_4复合材料,采用XRD、SEM、TEM、UV-Vis DRS、FTIR、BET和XPS等表征手段对复合材料的形貌结构、光学特性和化学组成进行了表征.利用合成材料光催化降解双酚AF(BPAF),研究了溶液初始pH、溶解性有机质(DOM)对BPAF降解的影响,并对光催化降解机理进行了探讨.结果表明,在pH=7时,5%Ag/P-g-C_3N_4表现出最强的光催化性能,其在90 min内对BPAF的降解率达到100%.DOM在低浓度(0.5 mg·L~(-1))时促进了BPAF的光降解,而在高浓度时(2~10 mg·L~(-1))抑制了BPAF的光降解.活性基团捕获实验结果表明,在Ag/P-g-C_3N_4降解BPAF过程中,h~+和·OH起主要的作用,直接参与了BPAF的降解.相对于P-g-C_3N_4,Ag/P-g-C_3N_4光催化性能的增强主要是因为Ag的负载促进了e~-和h~+的分离,同时Ag单质的SPR效应提高了复合材料对可见光的吸收率,延长了光生载流子的寿命.  相似文献   

11.
A novel visible light-active photocatalyst formulation(NdT/OP) was obtained by supporting N-doped TiO_2(NdT) particles on up-conversion luminescent organic phosphors(OP). The photocatalytic activity of such catalysts was evaluated for the mineralization process of spiramycin in aqueous solution. The effect of NdT loading in the range 15–60 wt.% on bulk and surface characteristics of NdT/OP catalysts was investigated by several chemicophysical characterization techniques. The photocatalytic performance of NdT/OP catalysts in the removal of spyramicin from aqueous solution was assessed through photocatalytic tests under visible light irradiation. Total organic carbon(TOC) of aqueous solution,and CO and CO_2 gas concentrations evolved during the photodegradation were analyzed. A dramatic enhancement of photocatalytic activity of the photostructured visible active NdT/OP catalysts,compared to NdT catalyst,was observed. Only CO_2 was detected in gas-phase during visible light irradiation,proving that the photocatalytic process is effective in the mineralization of spiramycin,reaching very high values of TOC removal. The photocatalyst NdT/OP at 30 wt.% of NdT loading showed the highest photocatalytic activity(58%of TOC removed after 180 min irradiation against only 31% removal after 300 min of irradiation of NdT). We attribute this enhanced activity to the high effectiveness in the utilization of visible light through improved light harvesting and exploiting. OP particles act as "photoactive support",able to be excited by the external visible light irradiation,and reissue luminescence of wavelength suitable to promote NdT photomineralization activity.  相似文献   

12.
ZnBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO4 were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–Vis diffuse reflectance. ZnBiYO4 crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO4 were a = b = 11.176479 Å and c = 10.014323 Å. The band gap of ZnBiYO4 was estimated to be 1.58 eV. The photocatalytic activity of ZnBiYO4 was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiYO4 had higher catalytic activity compared with N-doped TiO2 under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO4 or N-doped TiO2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 min− 1 for ZnBiYO4 and N-doped TiO2, respectively. After visible light irradiation for 220 min with ZnBiYO4 as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO42 − and NO3, and evolution of CO2 revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatography–mass spectrometry. The ZnBiYO4/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems.  相似文献   

13.
为获得高效催化活性的光催化材料,研究不同煅烧氛围对材料在可见光下催化性能的影响,以膨胀珍珠岩(EP)为载体,采用溶胶-凝胶法,在不同煅烧氛围(O2和/或NH3)下制备Fe2O3/TiO2负载EP的光催化复合材料〔Fe2O3-TEP(O2)、Fe2O3-TEP(NH3)、Fe2O3-TEP(O2,NH3)、Fe2O3-TEP(NH3,O2)〕,采用EDS(X-射线色散能谱)、BET(比表面积及孔径分析)、XRD(X射线衍射)、SEM(扫描电子显微镜)、XPS(X射线光电子能谱)等对复合材料进行表征,并研究了其在可见光下对罗丹明B的光催化降解效果.结果表明:①复合材料成功负载了Ti、Fe元素,负载的TiO2以锐钛矿型存在,Fe2O3的掺杂增强了TiO2对可见光的响应能力;②不同的煅烧氛围明显影响复合材料的晶粒尺寸、比表面积和光催化性能,其中,Fe2O3-TEP(O2,NH3)的光催化性能最好,4 h后罗丹明B降解率达到87.59%,Fe2O3-TEP(NH3,O2)、Fe2O3-TEP(O2)和Fe2O3-TEP(NH3)4 h后对罗丹明B的降解率则分别为65.02%、62.48%和47.48%;③在试验条件下,复合材料的光催化反应符合一阶反应动力学方程,Fe2O3-TEP(O2,NH3)、Fe2O3-TEP(NH3,O2)、Fe2O3-TEP(O2)和Fe2O3-TEP(NH3)相应的降解速率常数分别为0.008 3、0.004 3、0.004 3和0.002 7 min-1.研究显示,通过溶胶-凝胶法所制备的复合材料(Fe2O3-TEP)经煅烧后所得矿相均一;Fe2O3掺杂TiO2可形成Ti—O—Fe键,减小TiO2固有的禁带宽度;复合材料光催化性能也受到煅烧氛围的影响,先O2后NH3煅烧条件下所得材料的光催化性能最佳.   相似文献   

14.
Highly active mesoporous TiO_2 of about 6 nm crystal size and 280.7 m~2/g specific surface areas has been successfully synthesized via controlled hydrolysis of titanium butoxide at acidic medium. It was characterized by means of XRD(X-ray diffraction), SEM(scanning electron microscopy), TEM(transmission electron microscopy), FT-IR(Fourier transform infrared spectroscopy), TGA(thermogravimetric analysis), DSC(differential scanning calorimetry) and BET(Brunauer–Emmett–Teller) surface area. The degradation of dichlorophenol-indophenol(DCPIP) under ultraviolet(UV) light was studied to evaluate the photocatalytic activity of samples. The effects of different parameters and kinetics were investigated. Accordingly, a complete degradation of DCPIP dye was achieved by applying the optimal operational conditions of 1 g/L of catalyst, 10 mg/L of DCPIP, pH of 3 and the temperature at 25 ± 3°C after 3 min under UV irradiation. Meanwhile, the Langmuir–Hinshelwood kinetic model described the variations in pure photocatalytic branch in consistent with a first order power law model.The results proved that the prepared TiO_2 nanoparticle has a photocatalytic activity significantly better than Degussa P-25.  相似文献   

15.
Fish scale (FS) loaded TiO2 composites were investigated as photocatalysts in degradation of Methyl Orange under solar light irradiation. Composites were prepared through sol-gel method by varying mass ratio of TiO2/FS at 90:10, 70:30 and 50:50, respectively. The catalysts prepared in this study were characterized by using XRD, SEM, FT-IR and nitrogen sorption. The effects of solar irradiation, mass ratio of TiO2/FS composites, irradiation time and catalyst loadings were studied. Synergistic effect was found in TiO2/FS of 90:10 composite which performed higher photocatalytic degradation than synthesized TiO2 under solar light irradiation. However, further increasing fish scale content in the composites reduced the photocatalytic activity drastically. Under solar light irradiation, all the catalysts in this study exhibited photocatalytic activity, except TiO2/FS of 50:50 composite that only acted as a weak biosorbent without performing any photocatalytic property. Photocatalytic degradation increased with increasing catalyst loading and irradiation time but decreased with increased of initial dye concentration.  相似文献   

16.
Polypropylene (PP) meltblown fibers were coated with titanium dioxide (TiO2) nanoparticles using layer-by-layer (LbL) deposition technique. The fibers were first modified with 3 layers of poly(4-styrenesulfonic acid) (PSS) and poly(diallyl-dimethylammonium chloride) (PDADMAC) to improve the anchoring of the TiO2 nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic TiO2 nanoparticles to construct TiO2/PDADMAC bilayer in the LbL fashion. The number of deposited TiO2/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust TiO2 loading. The LbL technique showed higher TiO2 loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue (MB). Results showed that the TiO2 modified fibers exhibited excellent photocatalytic activity efficiency similar to that of TiO2 powder dispersed in solution. The deposition of TiO2 3 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4 hr. TiO2-LbL constructions also preserved TiO2 adhesion on substrate surface after 1 cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of TiO2 particles from the substrate outer surface. However, even in the third cycle, the TiO2 modified fibers are still moderately effective as it could remove more than 95% of MB after 8 hr of treatment.  相似文献   

17.
It is important to develop efficient and economic techniques for removing volatile organic compounds (VOCs) in indoor air. Heterogeneous TiO2-based semiconductors are a promising technology for achieving this goal. Anatase/brookite/rutile tricrystalline TiO2 with mesoporous structure was synthesized by a low-temperature hydrothermal route in the presence of HNO3. The obtained samples were characterized by X-ray diffraction and N2 adsorption–desorption isotherm. The photocatalytic activity was evaluated by photocatalytic decomposition of toluene in air under UV light illumination. The results show that tricrystalline TiO2 exhibited higher photocatalytic activity and durability toward gaseous toluene than bicrystalline TiO2, due to the synergistic effects of high surface area, uniform mesoporous structure and junctions among mixed phases. The tricrystalline TiO2 prepared at RHNO3 = 0.8, containing 80.7% anatase, 15.6% brookite and 3.7% rutile, exhibited the highest photocatalytic activity, about 3.85-fold higher than that of P25. The high activity did not significantly degrade even after five reuse cycles. In conclusion, it is expected that our study regarding gas-phase degradation of toluene over tricrystalline TiO2 will enrich the chemistry of the TiO2-based materials as photocatalysts for environmental remediation and stimulate further research interest on this intriguing topic.  相似文献   

18.
利用静电纺丝技术原位制备了准一维结构CaIn_2O_4-In_2O_3纳米带.采用XRD、SEM、TEM、EDS、UV-vis DRS、N_2吸附-脱附曲线等对合成的光催化剂进行表征,并以对苯二甲酸(TA)为分子探针物质,结合荧光技术探讨了光催化反应过程中·OH自由基的变化.以亚甲基蓝(MB)为降解目标物,考察了CaIn_2O_4-In_2O_3纳米带的光催化活性,并研究了溶液pH及MB初始浓度对其光催化活性的影响.研究结果表明,宽度约为(663±75) nm的CaIn_2O_4-In_2O_3纳米带由直径约为80 nm的纳米颗粒组成,且纳米颗粒之间有一定的孔隙.模拟太阳光辐照120 min,MB的降解率为76%,且降解过程服从一级动力学模型.CaIn_2O_4-In_2O_3纳米带在酸性环境中显正电性,且光催化反应体系中·OH自由基的生成量随反应时间线性增加.CaIn_2O_4与In_2O_3的耦合使得合成的光催化剂在模拟太阳光下具有良好的光催化活性.  相似文献   

19.
ZnBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO4 were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis diffuse reflectance. ZnBiYO4 crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO4 were a = b = 11.176479 Å and c= 10.014323 Å. The band gap of ZnBiYO4 was estimated to be 1.58 eV. The photocatalytic activity of ZnBiYO4 was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiYO4 had higher catalytic activity compared with N-doped TiO2 under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO4 or N-doped TiO2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 min-1 for ZnBiYO4 and N-doped TiO2, respectively. After visible light irradiation for 220 min with ZnBiYO4 as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO42- and NO3-, and evolution of CO2 revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatography- mass spectrometry. The ZnBiYO4/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems.  相似文献   

20.
运用一步热聚合法成功制备出二维超薄g-C_3N_4(UCN)纳米片,通过透射电子显微镜、比表面测定仪、紫外可见漫反射光谱、荧光光谱对UCN的形貌及光学性能进行表征,并利用g-C_3N_4对水相中的双氯芬酸钠(DCF)进行了光催化降解实验.结果表明,UCN具有二维超薄纳米片结构,且具有较高的比表面积、较强的可见光吸收能力及空穴-电子转移能力.UCN的光催化活性优于块状g-C_3N_4,过硫酸盐(PDS)的加入对双氯芬酸钠的降解有促进作用,UCN/PDS体系中对双氯芬酸钠降解起主导作用的活性物种为O【math203z】,经过150 min的反应,双氯芬酸钠的矿化率达到78%.双氯芬酸钠在UCN/PDS体系下的光催化降解符合一级动力学规律和Langmuir-Hinshelwood模型,DCF的光催化降解在偏酸和偏碱性的情况下具有较快的反应速率.DCF在河水中的反应速率是超纯水中的3.4倍.循环实验表明,UCN具有很好的光催化稳定性.  相似文献   

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