Visible Light-induced Cr-doped SrTiO_3-g-C_3N_4 Composite for Improved Photocatalytic Performance

Novel visible light-induced Cr-doped Sr Ti O3-g-C3N4 composite photocatalysts were synthesized by introducing polymeric g-C3N4. The composite photocatalyst was characterized by X-ray diffraction(XRD), high-resolution transmission electron microscopy(HRTEM), Fourier transform infrared(FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy, photoluminescence(PL) spectroscopy and BET surface area measurements. The photocatalytic oxidation ability of the novel composite photocatalyst was evaluated using methyl orange(MO) as a target pollutant. The photocatalysts exhibited a significantly enhanced photocatalytic performance in degrading MO. The optimal g-C3N4 content for the photodegradation activity of the composite photocatalysts was determined. The as-prepared composite photocatalyst exhibits an improved photocatalytic activity due to enhancement of photo-generated electron-hole separation at the interface.     

Mass Production of Bi_3NbO_7/Bi_2Zn_(2/3)Nb_(4/3)O_7 Composites and Their Visible-light Photocatalytic Activity

Series Bi_3NbO_7/Bi_2Zn_(2/3)Nb_(4/3)O_7 (BN/BZN) composites were synthesized through a facile solid state reaction method. The products were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM) and UV-vis diffuse reflectance spectroscopy(DRS). When BN: BZN=0.1 mole ratio, the BN/BZN composite showed the best visible-light-driven photocatalytic performance, which decomposed nearly 100% of Rh B(10 ppm, p H=3-4) within 40 min. The results demonstrated that in-situ solid state synthesis of BN/BZN composites could be an efficient strategy to develop new photocatalyst for environmental remediation.     

Ag/TiO2纳米粒子的制备与表征

为了扩大纳米TiO_2在可见光范围的吸收,进行在纳米TiO_2中掺入Ag实验.以工业级偏钛酸、硝酸银为主要实验原料,采用一种简易的方法制备出Ag/TiO_2纳米粒子,并通过X线衍射(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外一可见光吸收光谱(UV-vis)对该粒子进行表征.结果表明,二氧化钛以锐钛型晶型,银以单质的形式存在于纳米复合粒子中;Ag的结合能367.476 eV(3d_(3/2))与373.453 eV(3d_(5/2))分别比纯银的结合能368.4 eV(3d_(3/2))与374.4 eV(3d_(5/2))低,这是由于制备Ag/TiO_2时煅烧温度较纯银高,银簇生长较大引起的;并显示复合粒子的粒径约为30 nm;Ag/TiO_2纳米粒子感应波长明显红移,增强了纳米TiO_2在可见光范围内的吸收.     

液相沉积法制备掺银TiO2薄膜及光催化性能

为了提高TiO2薄膜光催化剂的活性,通过在氟钛酸铵、硼酸混合溶液中加入硝酸银,应用液相沉积法(LPD)制备了掺银TiO2薄膜.采用XRD、SEM、XPS、UV-vis等手段对其组成、表面形貌和结构进行了测试表征;并以甲基橙为模型物,进行降解实验评价Ag-TiO2薄膜的光催化性能.实验结果表明:硼酸/氟钛酸铵摩尔比为2～4,热处理温度为400℃,硝酸银掺杂量为0.03 mol/L时,Ag-TiO2薄膜具有良好的锐钛矿相晶型,同时具有较高的光催化性能.     

NH2-UiO-66/BiOBr/Bi2S3光催化剂的合成及其光催化性能

采用溶剂热法制备NH₂-UiO-66/BiOBr/Bi₂S₃（UBB）三元复合光催化剂,利用X射线衍射（XRD）、扫描电镜（SEM）表征该催化剂的晶体结构和微观形貌,为了评价其光催化活性及稳定性,在可见光下催化降解有色染料亚甲基蓝（MB,20 mg/L）和罗丹明B（RhB,20 mg/L）。结果表明:NH₂-UiO-66的含量为2%时,UBB的光催化活性最好,对MB的降解率在60 min内达到93.5%,对RhB的降解率在30 min内达到98.3%;MB和RhB初始浓度提高到100 mg/L时,光催化降解率仍保持在70%以上;4次循环试验后,UBB的催化活性无明显降低。本文采用紫外可见漫反射光谱（UV-vis DRS）、荧光光谱（PL）和阻抗（EIS）的3种表征方法,分析UBB光催化性能变化的原因,并结合莫特-肖特基（M-S）曲线、活性物质捕捉实验结果,提出适用于UBB三元体系的双Z型电子转移机制。     

Hydrothermally Synthesizing Nanospheres of Pd Loaded TiO<Subscript>2</Subscript> for Photocatalytically Reducing CO<Subscript>2</Subscript> in Isopropanol to Isopropyl Formate

Photocatalytic reduction of CO₂ was carried out on villiform spherical catalysts of Pd-TiO₂ in isopropanol solution. The catalysts were synthesized by hydrothermal method, their structures, morphologies and optical absorption properties were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV-vis absorption spectroscopy (UV-vis). The photocatalytic activities with different loading amounts and morphologies were evaluated for determining the dominant effect and optimizing the catalyst preparation. Based on a villiform spherical TiO₂ with the largest specific surface area in our experiments, we prepared a set of catalysts with various loading amounts of palladium and tested them by bubbling CO₂ through the slurry of catalyst and isopropanol. The highest formation rate of isopropyl formate was 276.6 μmol/g·cat/h. Eventually we proposed the reaction mechanism.     

Preparation and Enhanced Daylight-Induced Photo-Catalytic Activity of Transparent C-Doped TiO_2 Thin Films

The transparent C-doped TiO2 nanostructure films were fabricated on the silicate glass substrates by sol-gel spin-coated method. The as-prepared films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectra (UV-vis) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was evaluated via the photocatalytic oxidation of methylene blue in aqueous under daylight irradiation at room temperature. The results show that the daylight-induced photocatalytic activities of the as-prepared films are improved by the C-doping. The calcination temperatures significantly affect the morphology, microstructure and photocatalytic activity of the as-prepared samples. At 723 K, the C-doped TiO2 films exhibit the highest photocatalytic activity due to the synergetic effects of good crystallization, appropriate oxygen vacancies and strong absorption in the near UV and visible-light region.     

Fabrication of BiVO_4:Effect of Structure and Morphology on Photocatalytic Activity and Its Methylene Blue Decomposition Mechanism

BiVO_4 photocatalysts were synthesized by a surfactant free hydrothermal method without any further treatments,and characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),ultraviolet-visible diffuse reflectance spectroscopy(UV-vis DRS),Raman spectroscopy,and Brunauer-Emmett-Teller(BET) surface area techniques.The photocatalytic activity was evaluated for the degradation of the methylene blue(MB) under visible light irradiation.Seen from the structural and morphological characterization,it is stated that the obtained samples present monoclinic phase,and the pH value has significant influence on the morphologies.The enhanced photocatalytic performance was associated with its crystallinity,unique morphology,band gap energy,BET specific surface area,surface charge and adsorption capacity.The recycle experiments results show that the BiVO_4 photocatalysts have excellent photo-stability,and we deduced a possible mechanism by examining the effects of the active species involved in the photocatalytic process for MB photocatalytic degradation.     

Fabrication of BiVO<Subscript>4</Subscript>: Effect of structure and morphology on photocatalytic activity and its methylene blue decomposition mechanism

BiVO₄ photocatalysts were synthesized by a surfactant free hydrothermal method without any further treatments, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), Raman spectroscopy, and Brunauer-Emmett-Teller (BET) surface area techniques. The photocatalytic activity was evaluated for the degradation of the methylene blue (MB) under visible light irradiation. Seen from the structural and morphological characterization, it is stated that the obtained samples present monoclinic phase, and the pH value has significant influence on the morphologies. The enhanced photocatalytic performance was associated with its crystallinity, unique morphology, band gap energy, BET specific surface area, surface charge and adsorption capacity. The recycle experiments results show that the BiVO₄ photocatalysts have excellent photo-stability, and we deduced a possible mechanism by examining the effects of the active species involved in the photocatalytic process for MB photocatalytic degradation.     

A facile synthesis of Ag Modified ZnO nanocrystals with enhanced photocatalytic activity

Ag modified ZnO (Ag/ZnO) nanocrystals were prepared by a facile and low temperature wet chemical method. The phase structures, morphologies, and optical properties of the as-prepared samples were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), the Brumauer-Emmett-Teller (BET) surface area, UV-vis diffuse reflectance spectroscopy and photoluminescence (PL) spectra, respectively. The photocatalytic performance of Ag/ZnO with diffent Ag contents was measured with the degradation of methyl orange (MO) at room temperature under UV light irradiation. The experimental results indicated that the well-crystalline ZnO nanopaticles with a size of ca. 4.5 nm exhibited a high photocatalytic activity for the degradation of MO with the apparent rate constant (k) of 1.57 ×10-2 min-1, and the photocatalytic activities of ZnO were further enhanced by modification with silver. When the Ag loading was 3mol%, Ag/ZnO showed the highest photocatalytic acitivity with a k value of 5.452×10-2 min-1, which is 3.5 and 2.5 time more than that of ZnO and commercial P25, respectively.     

Montmorillonite supported titanium/antimony catalyst: Preparation,characterization and immobilization

Montmorillonite supported titanium(Ti-MMT) or antimony catalyst(Sb-MMT) has been a hot area of research on preparing polyethylene terephthalate/montmorillonite(PET/MMT) nanocomposites by in situ polymerization. So removal of Ti or Sb from Ti-MMT or Sb-MMT is not expected during in situ polymerization. Studies on immobilization of Ti or Sb on Ti-MMT or Sb-MMT are seldom reported. In this work, a series of montmorillonite supported catalysts of titanium(Ti-MMT) or antimony(Sb-MMT) and cointercalated montmorillonite of titanium and antimony(Ti/Sb-MMT) were prepared by(1) the reaction of sodium bentonite suspension with intercalating solution containing titanium tetrachloride and/or antimony chloride, and(2) drying or calcinating the products at different temperature(100, 150, 240, 350 and 450 ℃). The physicochemical properties of these MMT supported catalysts were studied by X-ray diffraction(XRD), fourier transform infrared spectroscopy(FT-IR), inductively coupled plasma optical emission spectrometer(ICPOES), N 2 adsorption/desorption isotherms, UV-visible diffuse reflectance spectroscopy(UV-vis) and transmission electron microscopy(TEM). The immobile character of Ti or Sb on MMT supported catalysts was evaluated by a two-step method in deionized water or ethylene glycol. Several results were obtained, i e,(a) during the preparation, with an increase in drying or calcinating temperature, the amount of titanium and/or antimony species remained on these MMT supported catalysts decreased,(b) the experiments about immobile character of Ti or/and Sb showed that with an increase in drying or calcinating temperature, the immobilization of Ti and/or Sb species remained on these MMT supported catalysts increased gradually,(c) Ti-MMT calcinated at 450 ℃ had the biggest pore volume, which means Ti-MMT had the best adsorption application prospect.     

Preparation and enhanced daylight-induced photo-catalytic activity of transparent C-Doped TiO<Subscript>2</Subscript> thin films

The transparent C-doped TiO₂ nanostructure films were fabricated on the silicate glass substrates by sol-gel spin-coated method. The as-prepared films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectra (UV-vis) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was evaluated via the photo-catalytic oxidation of methylene blue in aqueous under daylight irradiation at room temperature. The results show that the daylight-induced photocatalytic activities of the as-prepared films are improved by the C-doping. The calcination temperatures significantly affect the morphology, microstructure and photocatalytic activity of the as-prepared samples. At 723 K, the C-doped TiO₂ films exhibit the highest photocatalytic activity due to the synergetic effects of good crystallization, appropriate oxygen vacancies and strong absorption in the near UV and visible-light region.     

Enhanced photocatalytic activity of （La, N） co-doped TiO2 by TiCl4 sol-gel autoigniting synthesis

(La, N) co-doped TiO2 photocatalysts were synthesized using TiCl4 sol-gel autoigniting synthesis (SAS) starting from a plished in the formation of TiO2 nanocrystals. The prepared samples were characterized by using X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS) and UV-vis diffuse reflectance spectra. The results indicated that nitrogen and lanthanum were incorporated into the lattice and interstices of titania nanocrystals, which resulted in narrowing the band gap and promoting the separation of photoexcited hole-electron pairs, respectively, and showing expected red-shifts and enhanced photocatalytic activity under visible light. The mechanism on nitrogen doping and enhancement in photocatalytic activity of (La, N) co-doped titania by SAS was discussed in detail.     

氯氧化铋/氧化亚铜复合材料的制备及其可见光催化性能

通过水热法成功制备了BiOCl/Cu₂O 复合材料, 是一种良好的可见光响应的光催化剂。通过X 射线衍射(XRD)、扫描电子显微镜(SEM)、紫外可见漫反射光谱(UV-vis) 和电化学阻抗谱(EIS) 等分析方法对BiOCl/Cu₂O 复合材料进行表征分析。以酸性橙(AO7) 为目标污染物进行光催化降解实验, 探究了BiOCl/Cu₂O 复合材料的光催化性能和降解机制。XRD 结果表明, 随着BiOCl 含量的增多, BiOCl 的衍射强度逐渐上升。SEM 结果表明, BiOCl 小纳米片附着在相对较大的八面体Cu₂O 表面形成复合结构。通过UV-vis 和EIS 分析结果可知, 复合材料的带隙相较于Cu₂O 略微增大但其阻抗明显变小。降解实验结果表明, 质量比为3 : 5 的BiOCl/Cu₂O 复合材料在90 min时的可见光催化降解率(56.8%) 明显高于Cu₂O 的降解率(26.3%), 其降解速率常数(0.009 3 min^-1) 是纯Cu₂O(0.003 3 min^-1) 的2.8 倍。自由基捕获实验表明BiOCl/Cu₂O 复合材料光催化过程中起主要作用的活性物种是超氧自由基(·O_{2^- )。6 次循环降解实验后光催化剂BiOCl/Cu2O(3 : 5) 对AO7 的降解率仍可达到48.3%。BiOCl 与Cu2O形成的异质结构在一定程度上降低了表面转移电阻, 加快了光催化过程中光生电子的转移速率, 提高了光生电子和空穴的分离率, 增强了光催化效果。}     

无皂乳液聚合制备PMMA／MMT纳米复合材料的研究

采用离子交换法,用溴化烯丙基三乙基铵对钠基蒙脱土进行改性制备了有机蒙脱土,再以甲基丙烯酸甲酯（MMA）为单体,过硫酸钾为引发剂,通过无皂乳液聚合制备聚甲基丙烯酸甲酯朦脱土（PMM-MMT）纳米复合材料。采用傅里叶变换红外（FTIR）、X-射线衍射（XRD）和扫描电镜（SEM）等手段对有机蒙脱土和复合材料的结构进行表征。结果表明：溴化烯丙基三乙基铵成功插层到蒙脱土层间,层间距由1．32nm增大到1．44nm;FTIR和XRD测试结果表明不同蒙脱土含量的PMMA/MMT纳米复合材料均具有剥离型结构;SEM测试结果表明PMMA/MMT纳米复合粒子的粒径随蒙脱土含量的增加而减小。     

复合铌酸盐的合成和光催化活性的研究

利用光催化剂降解有机染料具有很好的应用前景,光催化材料在光催化反应中起着重要的作用,但是如何制备化学性质稳定、在可见光下具有高的催化活性的催化剂一直是人们探索的一个主题。以Ag2O、Nb2O5、Na2CO3为前驱物,经高温固相反应法合成了具有不同Na/Ag摩尔比的（AgNbO3）1-x（NaNbO3）x复合铌酸盐。采用X-射线粉末衍射（XRD）、紫外-可见漫反射谱（UV-vis DRS）等方法对样品的结构和光谱响应特征进行了表征,以亚甲基蓝的降解反应为探针考察不同Na/Ag摩尔比的（AgNbO3）1-x（NaNbO3）x复合铌酸盐在可见光下的光催化活性。结果表明,由高温固相法合成出的复合铌酸盐的结构随着Na/Ag摩尔比的变化而变化,光谱响应特征随Na/Ag摩尔比的减小逐渐红移,而对亚甲基蓝的降解性能随Na/Ag呈规律性变化,其中（AgNbO3）0.6（NaNbO3）0.4复合铌酸盐呈现最好的光催化活性。     

Meso-macroporous Fe-doped Cu O: Synthesis,characterization, and structurally enhanced adsorption and visible-light photocatalytic activity

The meso-macroporous Fe-doped Cu O was prepared by a simple hydrothermal method combined with post-annealing. The samples were characterized by X-ray powder diffraction(XRD), scanning electron microscopy(SEM), Brunauer-Emmett-Teller N2 adsorption-desorption analyses and UV-vis diffuses reflectance spectroscopy. The Fe-doped Cu O sample shows higher adsorption capacity and photocatalytic activity for xanthate degradation than pure Cu O under visible light irradiation. In addition, the adsorption process is found to fit Langmuir isotherms and pseudo-second-order kinetics. The the first order kinetic Langmuir Hinshelwood model was used to study the reaction kinetics of photocatalytic degradation, and the apparent rate constant( k) was calculated. The value of k for Fe-doped Cu O is 1.5 times that of pure Cu O. The higher photocatalytic activity of Fe-doped Cu O is attributed to higher specific surface area together with stronger visible light absorption.     

Preparation, characterization and photocatalytic property of Ag-loaded TiO2 powders using photodeposition method

The Ag particles were photodeposited on TiO₂ powder surface. The X-ray diffraction (XRD), Raman spectroscopy, transmittance electron microscopy (TEM), UV-vis diffused reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectrophotoscopy were used to investigate the structure and morphologies of the samples. It is found that the loaded Ag particles have no effect on the XRD patterns, and the Raman scattering becomes much stronger due to the surface Raman enhancing effect. The TEM images show that the TiO₂ grains are in the shape of short sticks, and the spherical Ag particles with hexagonal structure are adhered to the TiO₂ grain surface tightly. XPS result shows that the loaded Ag particles can not affect the chemical states of Ti and O, and they are mainly in the form of metal Ag. A wide plasmon absorption appears on the UV-vis spectra after Ag photodeposition. The loaded Ag further greatly decreases the PL intensity, which partly indicates the electron transfer from TiO₂ to Ag. The photocatalytic activities firstly increase with the content of loaded Ag, and then sharply decrease. Finally, the photocatalytic mechanism related to Ag-loaded TiO₂ powders was discussed in detail. Funded by the National Natural Science Foundation of China (No. 50702041), and the Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT, IRT0547), Ministry of Education, China     

Enhanced photocatalytic activity of (La, N) co-doped TiO_2 by TiCl_4 sol-gel autoigniting synthesis

(La, N) co-doped TiO2 photocatalysts were synthesized using TiCl4 sol-gel autoigniting synthesis (SAS) starting from a complex compound system of TiCl4-La(NO3)3-citric acid-NH4NO3-NH3?H2O, in which the (La, N) co-doped process was accom- plished in the formation of TiO2 nanocrystals. The prepared samples were characterized by using X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS) and UV-vis diffuse reflectance spectra. The results indicated that nitrogen and lanthanum were incorporated into the lattice and interstices of titania nanocrystals, which resulted in narrowing the band gap and promoting the sepa- ration of photoexcited hole-electron pairs, respectively, and showing expected red-shifts and enhanced photocatalytic activity under visible light. The mechanism on nitrogen doping and enhancement in photocatalytic activity of (La, N) co-doped titania by SAS was discussed in detail.     

Syntheses and Evaluations of CdS with Various Morphologies for Photocatalytically Reducing CO_2

A series of CdS with various shapes of microsphere, flower-like and leaf-like were templatefreely synthesized by a hydrothermal method. Powder X-ray diffraction(XRD), Brunauer-Emmett-Teller(BET), scanning electron microscopy(SEM) and UV-vis absorption spectroscopy(UV-vis) were applied to characterize the morphology, optical and other physical properties of the as-prepared CdS. An optical spectrum analyzer was used to measure the wavelength of the illuminant on the slurry in the activity evaluations of photocatalytic reduction of CO_2 over CdS. Both sources of cadmium and sulfur had great impact on the CdS morphology as can be seen in the SEM images. By means of a series of activity evaluations, the microspheric CdS made from cadmium nitrate and thioacetamide showed better photocatalytic activity for the reduction of CO_2 to methyl formate(MF) in methanol than the flower-like and leaf-like CdS catalysts.