Synthesis,characterization and enhanced visible-light photocatalytic activity of Zn2SnO4/C nanocomposites with truncated octahedron morphology

Novel Zn₂SnO₄/C nanocomposites with truncated octahedron morphology were constructed using a two-step hydrothermal synthesis route combined with subsequent calcination. The as-prepared samples were characterized by X–ray diffraction (XRD), Fourier transform infrared spectroscopy (FT–IR), Raman spectroscopy, field–emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), UV–vis diffuse reflection spectroscopy, photoluminescence spectroscopy (PL), and Brunauer–Emmett–Teller surface area measurements. The result of FESEM showed that the as-prepared Zn₂SnO₄/C nanocomposites are composed of numerous uniform nanoparticles with regular truncated octahedron morphology. Raman spectral characterization combined with HRTEM result revealed that a thin layer of carbon was attached on the surface of Zn₂SnO₄. Using rhodamine B (RhB) as a model organic pollutant, the visible-light photocatalytic activities of the as-prepared samples were investigated, and the photocatalytic mechanism was discussed. Compared with pure Zn₂SnO₄, Zn₂SnO₄/C nanocomposites exhibited much better visible-light photocatalytic activity. The increase in the photocatalytic activity of Zn₂SnO₄/C nanocomposites was mainly attributed to the enhancement of the optical absorption capability and efficient separation of photogenerated electron-hole pairs.     

Bi_2WO_6的静电纺丝法制备及其光催化性能

以聚乙烯吡咯烷酮（PVP）、钨酸铵[（NH4）10W12O41]和柠檬酸铋铵（C6H13BiN2O7.H2O）为原料,利用静电纺丝技术成功制备了PVP/C6H13BiN2O7.H2O-（NH4）10W12O41（简写为PVP/BiWO）前躯体,对PVP/BiWO缓慢控温处理制得Bi2WO6。采用差热-热重分析（TG-DTA）、X射线粉末衍射（XRD）、傅里叶红外光谱（FTIR）、X-射线光电子能谱（XPS）、场发射扫描电镜（FE-SEM）、紫外可见漫反射（UV-Vis-NIR/DR）等分析手段研究热处理温度对材料结构的影响,通过罗丹明B（RhB）光降解反应研究其光催化性能。结果表明,可见光照射下,热处理温度600℃时材料的光催化活性最好,并探讨了其光催化机理。     

Bi2WO6的静电纺丝法制备及其光催化性能

以聚乙烯吡咯烷酮(PVP)、钨酸铵[(NH4)10W12O41]和柠檬酸铋铵(C6H13BiN2O7.H2O)为原料,利用静电纺丝技术成功制备了PVP/C6H13BiN2O7.H2O-(NH4)10W12O41(简写为PVP/BiWO)前躯体,对PVP/BiWO缓慢控温处理制得Bi2WO6。采用差热-热重分析(TG-DTA)、X射线粉末衍射(XRD)、傅里叶红外光谱(FTIR)、X-射线光电子能谱(XPS)、场发射扫描电镜(FE-SEM)、紫外可见漫反射(UV-Vis-NIR/DR)等分析手段研究热处理温度对材料结构的影响,通过罗丹明B(RhB)光降解反应研究其光催化性能。结果表明,可见光照射下,热处理温度600℃时材料的光催化活性最好,并探讨了其光催化机理。     

Enhanced photocatalytic activity of La1-xSrxCoO3/Ag3PO4 induced by the synergistic effect of doping and heterojunction

This study sought to design and synthesize a series of perovskite-based La_1-xSr_xCoO₃/Ag₃PO₄ (with x = 0–1) heterojunction photocatalysts with different Strontium (Sr) doping contents by a simple sol-gel method and properties of the material were comprehensively characterized. Moreover, tetracycline (TC) was chosen as the target pollutant to assess the effect of Sr doping on the catalytic performance of LaCoO₃/Ag₃PO₄. Our results demonstrated that the partial replacement of La³⁺ with Sr²⁺ coupled with shifting Co³⁺ to the mixed-valence state of Co³⁺-Co⁴⁺ led to the formation of substantially more oxygen vacancies in the crystal lattice of La_1-xSr_xCoO₃/Ag₃PO₄. Therefore, the doped catalyst La_1-xSr_xCoO₃/Ag₃PO₄ exhibited enhanced photocatalytic performance. When x = 0.9, the obtained La_0·1Sr_0·9CoO₃/Ag₃PO₄ exhibit an optimal performance for TC degradation. Kinetic analyses demonstrated that the degradation rate constant of TC in La_0·1Sr_0·9CoO₃/Ag₃PO₄ system was 0.0098 min^?1, which is 1.78 times that of LaCoO₃/Ag₃PO₄, and 2.45 times that of SrCoO₃/Ag₃PO₄. Additionally, free radical sequestration experiments indicated that OH^?, h⁺, and O₂^?? all participated in the degradation of TC in the following order: h⁺>O₂^??>OH^?. Finally, analyses of photocatalytic mechanisms suggested that the enhanced photocatalytic activity of La_0·1Sr_0·9CoO₃/Ag₃PO₄ was due to its strong electron transfer properties and the formation of substantially more surface oxygen vacancies in Sr-doped La_0·1Sr_0·9CoO₃.     

Synthesis,properties and applications of ZnO nanomaterials with oxygen vacancies: A review

ZnO nanomaterials have attracted tremendous interest in the fields of photocatalysis, sensors, solar cells, supercapacitors, etc. However, the performance of intrinsic ZnO is limited by several factors such as insufficient light absorption, poor charge transport and low conductivity. Extensive studies have indicated that the controlled introduction of oxygen vacancies (V_O) into ZnO can manipulate their optical, electronic and surface properties, enabling their enhanced performance in various applications. Here, we present a state-of-the-art review on the various synthetic approaches of ZnO nanomaterials with V_O and their defect-related properties including structural characteristics, band structure, optical, electrical and ferromagnetic properties. In addition, their use in various applications such as photocatalysts, photoelectrodes, antibacterial agents, gas sensors, supercapacitors and other electronic devices related to V_O-rich ZnO are outlined. Furthermore, we offer some perspectives on the challenges and new directions in this field. We hope that this review would provide some useful information to the design, synthesis and applications of metal oxide nanomaterials with defects.     

La掺杂纳米TiO2的制备及光催化性能研究

采用溶胶-凝胶法制备了纯TiO₂和不同La掺杂量的TiO₂纳米粒子，对样品进行了TG-DTA、XRD和UV-Vis 吸收光谱分析，并以染料废水甲基橙为目标降解物，考察了样品的光催化性能。结果发现，La的掺杂抑制了TiO₂粒径的长大，细化了晶粒；La掺入到TiO₂的晶格中，引起了晶格的畸变和膨胀；La的掺杂使TiO₂的吸收带边发生了红移；适量La的掺杂可提高TiO₂的光催化性能。试验条件下，最佳掺杂摩尔分数为0.1％。     

Synthesis,structural characterization,and photocatalytic activity of Bi‐based nanoparticles

Bi‐based nanoparticles were successfully synthesized (500°C/2 h) following two intermediate‐temperature routes, Pechini and a combined method of mechanical milling/molten salts. Herein, α‐Bi₂O₃/Bi₂O₂CO₃ heterostructures were identified. These types of heterostructures have shown advantages to improve the visible light responsive activity of Bi‐based nanoparticles to facilitate the separation of photogenerated electron‐hole pairs. By fixing the experimental parameters, the synthesis route and Ag contents showed to play a very important role in the phase composition of the Ag‐containing samples; the formation of Bi/Ag‐Bi₂O₃/Bi₂O₂CO₃ and Ag/Ag‐Bi₂O₃/Bi₂O₂CO₃ complex hybrid structures were revealed. The α‐Bi₂O₃/Bi₂O₂CO₃ heterostructure prepared by combined method exhibited higher photocatalytic efficiency (66.84%) for degrading methylene blue (MB) depending on Bi₂O₂CO₃ component proportion. For the Ag‐containing hybrid structures, the performance of their catalytic activity did not show an increase with respect to α‐Bi₂O₃/Bi₂O₂CO₃. However, in these samples, the degradation efficiency was slightly enhanced with the efficient doping of Ag into the α‐Bi₂O₃ structure and the existence of Bi when the Pechini method was used. Also, a possible photocatalytic process for degrading MB is presented.     

An investigation on the photocatalytic activity of sub-stoichiometric TiO2-x coatings produced by suspension plasma spray

To enhance the photocatalytic activity, sub-stoichiometric TiO_2-x films were coated on stainless steel substrates by Suspension Plasma Spraying. Because the TiO₂ particles are exposed to high temperature during deposition by plasma spray, TiO_2-x coating are typically produced. To achieve different levels of oxygen vacancies, as-sprayed TiO_2-x coatings were annealed at four different temperatures for 48 h in air. In this work, the degradation of methylene blue was performed to evaluate the photocatalytic activity under visible light. The results indicated that oxygen vacancy positively affects the photocatalytic activity of TiO_2-x by introducing some energy levels into the bandgap of titania. Moreover, these energy levels could act as traps for photo-excited holes and electrons, reducing the recombination rate of charges, thus improving the photocatalytic activity under the visible lamp. Additionally, coatings were analyzed by X-ray diffraction, confocal laser microscopy, scanning electron microscopy, Raman spectroscopy, thermogravimetric analysis, Fourier-transform infrared spectroscopy, and UV–vis spectroscopy.     

片状纳米ZnO的合成及其光催化活性研究

以六次甲基四胺为沉淀剂,氯代十六烷基吡啶为形貌控制剂,采用水热-均匀沉淀法合成了片状ZnO微晶,考察了合成方法、沉淀剂用量及水热反应温度等条件对产物形貌、尺寸及光学性质的影响,并以甲基橙为模型污染物研究了样品的光催化性能。结果表明,所得样品均为六方纤锌矿型ZnO,当锌盐和六次甲基四胺的摩尔比为1∶2,采用水热-均匀沉淀法于120℃水热条件下反应所得到的样品其形貌最佳,且在250~400 nm波长范围内对光有很强的吸收,对甲基橙的光降解具有较高的光催化活性,自然光照5 h后甲基橙的脱色率可达90.8%。     

Design of TiO2 nanocrystals with enhanced sunlight photocatalytic activity by exploring calcining conditions

As a promising inorganic semiconductor photocatalyst, TiO₂ has been widespread concerned since 1972. However, its practical application is limited due to its low efficiency for utilizing solar light and rapid recombination of photo-generated charges. Here, we report a way to solve these problems by calcining TiO₂ samples under different conditions. It was found that the catalytic performance of TiO₂ catalysts was closely related to calcination temperature and calcination atmosphere. The XRD, Raman spectra, BET, UV–vis spectra, SEM and TG-DTA investigations of the catalysts revealed that the crystal structure of TiO₂, the specific surface area, and abundant oxygen vacancies were the primary factors influencing the performance of TiO₂ catalysts. Consequently, the TiO₂ nanocrystal calcined in a nitrogen/hydrogen mixed atmosphere at 300 °C for 3 h exhibited higher catalytic activity than others. These results demonstrated that annealing conditions can play an important role in catalyst activity.     

稀土掺杂纳米TiO2光催化剂制备及其光催化性能

采用溶胶-微波法制备掺杂不同稀土元素纳米TiO2光催化剂,借助XRD和UV-Vis吸收光谱等手段对其进行表征.以甲基橙为模拟污染物,考察样品的光催化性能.结果表明,适量的La3+、Nd3+、Eu3+、Gd3+和Y3+掺杂可提高TiO2样品的光催化活性,最佳掺杂物质的量分数分别为0.1%、0.1%、0.3%、0.2%和0...     

AgBr纳米粒子的制备及其光催化性能的研究

通过简单的沉淀法,加入适量浓度的表面活性剂十六烷基三甲基溴化铵（CTAB）制备纳米AgBr粒子。利用XRD、SEM表征手段证明了所制得的纳米粒子纯度高、粒径小、尺寸分布窄、稳定性好。通过UV-Vis表征可以知道,沉淀法制备的纳米粒子吸收波长范围可至可见光区域。在以紫外光及自然光（太阳光）为光源的条件下,经过60min的光催化降解反应,甲基橙（MO）的降解率可达到96％以上。与纳米二氧化钛粒子和纳米氧化锌粒子光催化性能相比,纳米溴化银不仅催化效率更高,而且在自然光照的条件下仍然可以保持很好的光催化性能。     

Au/TiO2复合物的制备、表征及其增强光催化灭菌活性

为提升TiO₂光催化活性克服其可见光响应能力差的问题,采用沉积-沉淀法制备了Au/TiO₂复合物光催化剂,利用X射线衍射（XRD）、傅里叶红外光谱（FTIR）、X射线光电子能谱（XPS）、紫外-可见漫反射光谱（UV-vis DRS）、荧光发射光谱等对样品进行了表征。XRD、FTIR和XPS结果表明,Au/TiO₂中TiO₂为锐钛矿相且Au成功沉积至TiO₂。UV-vis DRS和荧光发射光谱结果表明,适量Au修饰不仅能提高TiO₂对可见光的吸收,还可促进TiO₂光生电子-空穴对分离,有利于增强其光催化活性。自由基捕获实验证实,形成?OH的数量与光照时间成正比且?OH生成量越多,光催化活性越高。对比考察了Au/TiO₂和TiO₂在氙灯光源照射下对大肠杆菌的光催化杀灭作用,并探讨了Au负载量、光照时间、光照强度、光催化剂浓度等因素对灭菌性能的影响。结果表明：Au/TiO₂的光催化灭菌活性优于TiO₂,且与光照时间和光照强度均成正比;Au的适宜负载量为3%（质量分数）;3%Au/TiO₂在光照时间60min、光照强度7mW/cm²、光催化剂浓度100μg/mL的条件下,对大肠杆菌的杀灭效率高达91.3%。     

钆掺杂纳米二氧化钛光催化剂的制备及其光催化性能研究

以钛酸四正丁酯为原料,采用溶胶-凝胶法制备不同Gd3+掺杂量的纳米TiO2光催化剂,用500 W长弧氙灯模拟太阳光,并以甲基橙模拟水研究样品的光催化性能。结果表明,钆掺杂并没有改变纳米二氧化钛的晶型结构,微观形貌为球状颗粒,粒径约为30 nm;当掺杂摩尔分数为1.26%时,光催化性能最好,用量为1 g/L,反应2 h时,降解率达51%。     

Synthesis,characterization and photocatalytic activity study of aluminium doped BiSbO4 microflakes

Metal oxides have an extraordinary ability to generate charge carriers with significant importance in environmental remediation. For the degradation of different dyes, a one-step hydrothermal method was adopted to synthesize Al-doped BiSbO_4. While bismuth antimonate composite with reduced graphene oxide was synthesized by the simple ultra-sonication method. To investigate the structural confirmation, X-ray diffraction (XRD) was used. For studying morphology, scanning electron microscopy (SEM) was conducted. UV–Visible spectroscopy (UV) and Fourier transform infrared spectroscopy (FTIR) were used to observe the optical properties and vibrational modes of the as-synthesized BiSbO₄ nanoparticles and doped Al–BiSbO₄. The above-mentioned studies verify the formation of nanoparticles of Al-doped BiSbO₄. The synthesized composite was used to degrade the organic dyes such as methylene blue and crystal violet. The degradation efficiency of doped, undoped and composite is studied and compared. The results indicate the extraordinary efficiency of BiSbO₄/rGO composite to doped and bare samples for the degradation of dyes. It is confirmed by the degradation of different dyes that the BiSbO₄/rGO composite shows the best catalytic efficiency.     

Increasing the photocatalytic and fungicide activities of Ag3PO4 microcrystals under visible-light irradiation

The present study reports for the first time the performance of silver phosphate (Ag₃PO₄) microcrystals as photocatalyst (degradation of Rodamine B-RhB) and antifungal agent (against Candida albicans–C. albicans) under visible-light irradiation (455 nm). Ag₃PO₄ microcrystals were synthesized by a simple co-precipitation (CP) method at room temperature. The structural and electronic properties of the as-synthetized Ag₃PO₄ have been investigated before and after 4 cycles of RhB degradation under visible light using X-ray diffraction (XRD), micro-Raman spectroscopy, UV–Vis spectrophotometer and field emission scanning electron microscopy (FE-SEM) images. The antifungal activity was analyzed in planktonic cells and 48h-biofilm of C. albicans by colony forming units (CFU) counting, confocal laser and FE-SE microscopies. Statistical analysis was carried out using SPSS software. Morphological and structural modifications of Ag₃PO₄ were observed upon recycling. After 4 recycles, the material maintained its photodegradation property; an eightfold increase in the efficiency of Ag₃PO₄ was observed in planktonic cells and a two fold increase in biofilm when irradiated under visible light. Thus, higher antifungal effectiveness against C. albicans was obtained when associated with visible-light irradiation.     

Solar driven photocatalytic properties of Sm3+ doped ZnO nanocrystals

ZnO nanocrystals (NCs) doped with different Sm³⁺ concentrations were prepared by sol gel method. XRD analysis showed that the ZnO:Sm³⁺ NCs crystallized in the hexagonal wurtzite structure with a grain size varying from 61.4 nm to 72.6 nm, with Sm³⁺ concentration. Transmission electron microscopy (TEM) images indicated that ZnO NCs adopted a bimodal size distribution. X-ray photoelectron spectroscopy (XPS) revealed that Sm ions existed in trivalent state and substituted at the Zn²⁺ sites in the ZnO lattice. Raman spectra highlighted the presence of the LO mode, confirming the successful substitution of Zn²⁺ by Sm³⁺. Excitation and emission spectra highlighted the typical 4f-4f transitions of Sm³⁺. A photoluminescence (PL) quenching accompanied by a decrease of PL lifetime was observed for Sm³⁺ concentrations above 1.5%. The processes of excitation and de-excitation of the Sm³⁺ ions in ZnO NCs were discussed based on dipolar interactions between the excited ions. The ZnO:Sm³⁺ (1.5%) photocatalyst induced complete and fast photodegradation of RhB under sunlight irradiation. The photocatalytic mechanism is discussed based on the analysis of PL lifetimes. The role of oxygen vacancies on the reduction of Sm³⁺ ions and its impact on the photocatalytic process is also discussed.     

光催化沉积法制备Pd膜的改进及Pd膜性能表征

对光催化沉积法(PCD)制备Pd膜进行了改进,使含有TiO2与Pd2 的悬浮液膜层在多孔陶瓷膜表面形成液体薄膜,该薄膜在紫外光直接照射下发生光催化还原反应,烧结后得到含TiO2及Pd晶种的超薄膜层,用化学镀修饰得致密Pd膜.采用SEM、EDAX方法对所制的Pd膜表征结果表明,Pd膜厚度为5~6μm.在350~500℃和0.05~0.15 MPa下进行气体渗透实验,当温度为450℃时,H2渗透系数为4.07×10-6mol/(m2.s.Pa),N2的渗透量检测不出,高温热循环测试表明该Pd膜致密且具有良好的热稳性.     

锡酸铅纳米粒子的制备及其光催化性能

以有机碱四甲基氢氧化铵［N（CH₃）₄OH］为矿化剂,采用水热合成法制备锡酸铅（PbSnO₃）纳米粒子。通过X射线衍射（XRD）、热重-差式扫描量热分析（TG-DSC）和红外光谱分析（IR）等手段对产物的形成过程和结构进行表征,并研究了其对亚甲基蓝溶液的光催化降解性能。结果表明：由于采用有机碱四甲基氢氧化铵作为矿化剂,可以在较低的温度和较短的时间内制备出纯的立方相锡酸铅纳米粒子,其反应温度可降至120 ℃,反应时间可缩短至5 min;前躯体溶液pH是合成纯锡酸铅纳米粒子的关键,其值应在13以上。锡酸铅纳米粒子对亚甲基蓝溶液有良好的光催化降解效果,当催化剂用量为60 mg/L、反应时间为100 min时,亚甲基蓝的降解率可达88.5%。