MIL-101/P25复合材料的制备及光催化性能

采用水热法,将MIL-101负载到预处理过的P25表面,制得MIL-101/P25复合光催化材料,通过X射线衍射(XRD)、傅里叶变换红外(FTIR)、低温N2物理吸附-脱附(BET)、热重(TG)、场发射透射电镜(FETEM)和光致发光光谱(PL)等对催化剂进行结构表征,同时考察MIL-101及复合材料的稳定性,并且提出协同因子指标来定量评价复合带来的协同效应。结果表明MIL-101呈片状,与P25部分结合。复合后,MIL-101的稳定性得到提高。在适当的配比下,复合具有协同效应,当Cr(NO3)3·9H2O与P25的物质的量之比为1∶1时,复合材料对罗丹明B的可见光催化活性最高,协同因子达到1.64。复合材料对无色有机污染物水杨酸同样表现出良好的光催化效果。     

CO2在氨基改性MIL-101(Cr)中吸附的分子模拟

采用实验与分子模拟结合的方法研究298 K下CO₂在氨基改性得到的MIL-101（Cr）-NH₂和MIL-101（Cr）-ED（ED：乙二胺）上的吸附性能。比较MIL-101（Cr）、MIL-101（Cr）-NH₂和MIL-101（Cr）-ED的吸附等温线与吸附热的结果,表明采用直接合成改性法得到的MIL-101（Cr）-NH₂比采用合成后再改性得到的MIL-101（Cr）-ED有更高的CO₂吸附容量。进一步比较密度分布图和径向密度分布曲线,分析CO₂在氨基改性MIL-101（Cr）中的吸附位,表明在低压下CO₂首先吸附在MIL-101（Cr）微孔的超级四面体中,随着吸附压力的增大逐渐填充到更大的孔中。氨基的存在增加了CO₂的吸附位点,使MIL-101（Cr）-NH₂具有较高CO₂吸附容量;同时MIL-101（Cr）-ED中的ED分子的存在增加了CO₂的吸附位点,使MIL-101（Cr）-ED也具有较高CO₂吸附容量;但是MIL-101（Cr）-ED中的ED分子占据了MIL-101（Cr）中Cr的吸附位点,使Cr对CO₂的吸附强度减弱,同时可吸附位点少于MIL-101（Cr）-NH₂,导致其对CO₂的吸附容量少于MIL-101（Cr）-NH₂。     

BiOI负载MIL-101(Fe)@BiOI衍生BiFeO3@Fe2O3及其增强光催化性能

采用溶剂热法合成了MIL-101(Fe)@BiOI复合材料,然后将其煅烧制备光催化性能增强的BiFeO₃@Fe₂O₃@BiOI三元复合材料。采用X射线衍射、扫描电镜、紫外可见漫反射吸收光谱等测试手段表征复合材料的组成、结构、形貌。将复合材料用于可见光照射下光催化降解四环素,研究复合比例(质量比)、pH和浓度对光催化性能的影响。电化学阻抗谱、光电流响应和莫特-肖特基曲线测试分析表明三元复合材料BiFeO₃@Fe₂O₃@BiOI表现出更强的光电流响应和更低的电荷转移电阻。当BiFeO₃、Fe₂O₃和BiOI三者理论质量比为1∶1∶1时,中性条件下降解活性最高,四环素去除率为81%。     

BiOI负载MIL-101(Fe)@BiOI衍生BiFeO3@Fe2O3的增强光催化性能

采用溶剂热法合成了MIL-101(Fe)@BiOI复合材料,然后将其煅烧制备光催化性能增强的BiFeO₃@Fe₂O₃@BiOI三元复合材料。采用X射线衍射、扫描电镜、紫外可见漫反射吸收光谱等测试手段表征复合材料的组成、结构、形貌。将复合材料用于可见光照射下光催化降解四环素,研究复合比例(质量比)、pH和浓度对光催化性能的影响。电化学阻抗谱、光电流响应和莫特-肖特基曲线测试分析表明三元复合材料 BiFeO₃@Fe₂O₃@BiOI 表现出更强的光电流响应和更低的电荷转移电阻。当BiFeO₃、Fe₂O₃和BiOI三者理论质量比为1:1:1时,中性条件下降解活性最高,四环素去除率为81%。     

MoS2/g-C3N4复合材料的制备及可见光催化性能

首先在N-甲基吡咯烷酮溶液中超声剥离得到少层的MoS₂,将其与石墨相氮化碳（g-C₃N₄）复合,制得MoS₂/g-C₃N₄复合材料。采用X射线衍射（XRD）,扫描电镜（SEM）,X射线光电子能谱（XPS）,傅里叶变换红外光谱（FTIR）,Raman光谱,紫外-可见漫反射吸收光谱（DRS）和光致荧光（PL）技术对复合材料进行表征。可见光下考察MoS₂/g-C₃N₄复合材料光催化降解罗丹明B（RhB）的活性,结果表明：将少量MoS₂与g-C₃N₄复合可明显提高光催化活性,且1%（w/w）MoS₂/g-C₃N₄复合物的光催化活性最高,可能的原因是MoS₂和g-C₃N₄匹配的能带结构,增大了界面间电荷的传输,降低了光生电子-空穴的复合,进而提高了光催化活性。     

金属有机框架材料对[Fe(HB(pz)3)2]自旋转换行为的影响

通过在介孔结构金属有机框架材料MIL-101（Cr）和MIL-100（Al）的孔洞中合成自旋交叉化合物[Fe（HB（pz）₃）₂]的方法,可以得到SCO@MOF复合物。通过红外光谱（FTIR）、粉末X射线衍射（PXRD）、原子吸收光谱（AAS）以及气体吸附-脱附等进行了进一步测试。通过变温磁测量对复合材料的温度诱导自旋转换行为的研究表明,复合材料的自旋转换行为发生改变甚至是消失了。复合材料的这一现象可以解释为[Fe（HB（pz）₃）₂]在MOF主体材料的孔洞中形成了一种新的结晶相,且孔壁压力将会阻碍[Fe（HB（pz）₃）₂]从低自旋态向高自旋态转变。不同SCO@MOF复合物得到了相似的自旋转换行为结果。这确认了当自旋交叉化合物在金属有机框架材料孔洞中形成时,MOFs材料的限制压力或基体效应对其自旋转换行为的影响显然是至关重要的。     

层级纳米花环状Bi2O3/(BiO)2CO3复合材料光催化降解罗丹明B

通过程序升温水热法制备了层级纳米花状结构Bi₂O₃/（BiO）₂CO₃复合材料（简称BO/BCO）。采用X射线衍射（XRD）、紫外-可见漫反射吸收光谱（UV-Vis/DRS）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）和氮气吸附-脱附测定等方法对上述合成材料的晶型结构、组成、光吸收性质、形貌和表面物理化学性质进行了表征。结果表明,该复合材料中（BiO）₂CO₃的晶型为四方相,Bi₂O₃的晶型为单斜相,复合后的材料同时具有两者晶型结构。并且,合成时随着OH-的引入与反应时间的增加,复合材料中（BiO）₂CO₃的特征衍射峰强度逐渐降低,Bi₂O₃的特征衍射峰强度逐渐增加,证明了Bi₂O₃在样品中所占比例的增加。从UV-Vis/DRS吸收光谱分析结果显示,与单体（BiO）₂CO₃和单体Bi₂O₃相比,合成的BO/BCO复合材料的吸收边带发生偏移,且Bi₂O₃的引入有效增加其可见光区吸收。同时,样品由片状（BiO）₂CO₃生长为层级纳米花环状结构的BO/BCO-0.5,而层级结构的形成导致BO/BCO-0.5的带隙能变窄,且对于光电子的反射与散射发生改变,从而有利于光生电荷的转移与光的吸收效率。另外,以罗丹明B为模型分子,通过不同光源照射下的光催化活性实验,循环实验以及捕获实验对复合材料BO/BCO的光催化活性进行了研究。结果表明,与其他体系（单体Bi₂O₃和P25）相比,BO/BCO-0.5活性有明显提高,并且在多次循环实验后依然保持良好的稳定性。为此,根据捕获实验结果推测了BO/BCO复合材料可能的光催化反应机理。     

不同水热条件下TiO2/电气石复合材料的光催化机制

为了解决TiO₂纳米光催化剂易团聚、禁带宽度大的缺点,本文采用水热法制备了TiO₂/电气石（3%）复合材料,研究了水热时间（2~10 h）和水热温度（120~200℃）对TiO₂/电气石（3%）的光催化性能的影响。发现光催化降解罗丹明B的降解率由单独TiO₂的60%提高到加入电气石后的99.4%。电气石具备自发极化电场效应,降低了TiO₂的禁带宽度和光生电子和空穴的复合率。在水热温度160℃、水热时间4 h条件下制备的TiO₂/电气石（3%）表现出最高的光催化降解罗丹明B的性能。说明TiO₂与这种有自发极化的材料复合能够有效提高其光催化性能。     

TiO2/石墨烯复合材料的合成及光催化分解水产氢活性

利用石墨粉根据Hummers氧化法制得氧化石墨,并进一步还原得到石墨烯。采用溶胶-凝胶法以钛酸四丁酯和石墨烯为起始材料制备了二氧化钛(TiO₂)和石墨烯的复合光催化材料。研究了该复合材料在紫外-可见光以及可见光条件下的光催化分解水制氢活性。结果表明,紫外-可见光照射下,TiO₂/石墨烯复合光催化材料的光催化分解水产氢速率为8.6 μmol·h^-1,远大于同条件下商业P25的产氢速率 (4.5 μmol·h^-1),光解水产氢活性提高了近2倍;可见光下光照3 h,TiO₂/石墨烯复合材料的光催化分解水产氢量约为0.2 μmol。     

SnO2/TiO2纳米管复合光催化剂的性能及失活再生

基于微波水热法和微乳液法合成SnO₂/TiO₂纳米管复合光催化剂. 通过X射线衍射（XRD）、配有能量色散X射线光谱仪（EDX）的透射电镜（TEM）和电化学手段对光催化剂进行表征. 以甲苯为模型污染物,考察光催化剂在紫外光（UV）和真空远紫外光（VUV）下的性能及失活再生. 结果表明,SnO₂/TiO₂纳米管复合光催化剂形成三元异质结（锐钛矿相TiO₂（A-TiO₂）/金红石相TiO₂（R-TiO₂）、A-TiO₂/SnO₂和R-TiO₂/SnO₂异质结）,促使光生电子-空穴对的有效分离,提高光催化活性. SnO₂/TiO₂表现出最佳的光催化性能,UV和VUV条件下的甲苯降解率均达100%,CO₂生成速率（k₂）均为P25的3倍左右. 但由于UV光照矿化能力不足,中间产物易在催化剂表面累积. 随着UV光照时间的增加,SnO₂/TiO₂逐渐失活,20 h 后k₂由138.5 mg·m^-3·h^-1下降到76.1 mg·m^-3·h^-1. 利用VUV再生失活的SnO₂/TiO₂,过程中产生的·OH、O₂^-·、O（¹D）、O（³P）、O₃等活性物质可氧化吸附于催化剂活性位的难降解中间产物,使催化剂得以再生,12 h后k₂恢复到143.6 mg·m^-3·h^-1. UV和VUV的协同效应使UV降解耦合VUV再生成为一种可持续的光催化降解污染物模式.     

Photocatalytic Cr(VI) sequestration and photo-Fenton bisphenol A decomposition over white light responsive PANI/MIL-88A(Fe)

Polyaniline (PANI)/MIL-88A(Fe) (Px@M88) composites were constructed through a simple one-pot hydrothermal method. The photocatalytic and photo-Fenton activities of Px@M88 composites toward reduction of Cr(VI) and degradation organic pollutants were explored by white light irradiation. PANI, as a conductive polymer, can improve MIL-88A(Fe)’s conductivity and the efficiency of photogenerated e⁻–h⁺ pair separation. In the presence of H₂O₂, a photo-Fenton reaction occured to boost the degradation efficiency of organic pollutants like bisphenol A. In addition, P9@M88 showed excellent recycling and stability in cycling experiments. Finally, a possible reaction mechanism for photocatalytic degradation was proposed and verified by X-ray photoelectron spectroscopy and electron spin resonance determination and electrochemical characterizations.     

Photocatalytic Aerobic Oxidation of Biomass-Derived 5-HMF to DFF over MIL-53(Fe)/g-C3N4 Composite

A MIL-53(Fe)/g-C₃N₄ heterogeneous composite was synthesized and applied in photocatalytic oxidation of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF). The systematic investigation indicated that the introduction of MIL-53(Fe) into g-C₃N₄ increased the specific surface area, broadened the visible-light response region, and promoted the separation efficiency of the photo-generated electron-hole pairs. The 10% MIL-53(Fe)/g-C₃N₄ heterogeneous composite achieved the best photocatalytic oxidation activity with 74.5% of 5-HMF conversion under simulated sunlight, which was much higher than that of pristine g-C₃N₄ and MIL-53(Fe). The MIL-53(Fe)/g-C₃N₄ composite displayed good photocatalytic reusability and stability. Based on the characterization results and photocatalytic performance, a Z-scheme photocatalytic mechanism of the MIL-53(Fe)/g-C₃N₄ composite was suggested, and a possible reaction route was deduced.     

Assembling Ultrafine SnO2 Nanoparticles on MIL-101(Cr) Octahedrons for Efficient Fuel Photocatalytic Denitrification

Effectively reducing the concentration of nitrogen-containing compounds (NCCs) remains a significant but challenging task in environmental restoration. In this work, a novel step-scheme (S-scheme) SnO₂@MCr heterojunction was successfully fabricated via a facile hydrothermal method. At this heterojunction, MIL-101(Cr) octahedrons are decorated with highly dispersed SnO₂ quantum dots (QDs, approximate size 3 nm). The QDs are evenly wrapped around the MIL-101(Cr), forming an intriguing zero-dimensional/three-dimensional (0D/3D) S-scheme heterostructure. Under simulated sunlight irradiation (280 nm < λ < 980 nm), SnO₂@MCr demonstrated superior photoactivity toward the denitrification of pyridine, a typical NCC. The adsorption capacity and adsorption site of SnO2@MCr were also investigated. Tests using 20%SnO₂@MCr exhibited much higher activity than that of pure SnO₂ and MIL-101(Cr); the reduction ratio of Cr(VI) is rapidly increased to 95% after sunlight irradiation for 4 h. The improvement in the photocatalytic activity is attributed to (i) the high dispersion of SnO₂ QDs, (ii) the binding of the rich adsorption sites with pyridine molecules, and (iii) the formation of the S-scheme heterojunction between SnO₂ and MIL-101(Cr). Finally, the photocatalytic mechanism of pyridine was elucidated, and the possible intermediate products and degradation pathways were discussed.     

Chromium-based metal–organic framework/mesoporous carbon composite: synthesis,characterization and CO<Subscript>2</Subscript> adsorption

New composites of a water-stable chromium-based metal organic framework MIL-101 and mesoporous carbon CMK-3 were in situ synthesized with different ratios of MIL-101 and CMK-3 using the hydrothermal method. The composites as well as the parent materials were characterized by X-ray diffraction, thermo gravimetric analysis, scanning electron microscope, transmission electron microscope and nitrogen/carbon dioxide adsorption isotherms. The hybrid material possesses the same crystal structure and morphology as its parent MIL-101, and exhibits an enhancement in CO₂ adsorption uptakes when compared to MIL-101 and CMK-3. The increase in CO₂ uptakes was attributed to the combined effect of the formation of additional micropores, the enhancement of micropore volume and the activation of unsaturated metal sites by CMK-3 incorporation.     

BiVO_4/MOF复合材料的合成及其光催化性能

通过简单溶剂热法制备了一种新型复合光催化剂BiVO_4/M IL-53(Fe);运用XRD、SEM/EDS、FT-IR、N_2吸附-脱附和UV-vis DRS等手段对其进行表征,并对其光催化降解RhB活性进行了研究,提出了相应的光催化降解RhB的可能机理。结果表明,相较于单一BiVO_4材料,复合催化剂的比表面积增大,且其光催化效率相较于纯BiVO_4和MIL-53(Fe)也有了较大的提高;其中,BF-2复合材料的光催化活性最高,分别约为纯MIL-53 (Fe)和BiVO_4的5. 2倍和8. 1倍。同时,BiVO_4/MIL-53(Fe)复合光催化剂经过四次循环实验后,仍能保持较稳定的光催化活性和结构。     

WO3 Quantum Dots Decorated GO/Mg‐doped ZnO Composites for Enhanced Photocatalytic Activity under Nature Sunlight

Graphene oxide/Mg‐doped ZnO/tungsten oxide quantum dots composites (WQGOMZ) were prepared through co‐precipitation method, and were studied by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), Fluorescence spectra (FL), and UV–vis diffuse reflection spectra. Furthermore, the photocatalytic activity of resultant WQGOMZ was evaluated under nature sunlight. Experimental results showed that WO₃QDs can remarkably heighten the photocatalytic activity of GOMZ composite, in which is nearly 6.58 times higher than that of GOMZ composite. Simultaneously, WQGOMZ composites possess optical memory ability and maintain high photocatalytic stability for more than 40 days. The enhanced photocatalytic activity and optical memory ability are attributed to the effective synergistic effect between ZnO and WO₃QDs.     

Facile large scale synthesis of CuCr2O4/CuO nanocomposite using MOF route for photocatalytic degradation of methylene blue and tetracycline under visible light

MIL-101(Cr) template method has been employed successfully to synthesize CuCr₂O₄/CuO composite. The synthesized sample was characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy, N₂ adsorption–desorption isotherm (BET) analysis, and UV vis- diffuse reflectance spectroscopy (UV-DRS). The photocatalytic efficiency of the nanocomposite was evaluated towards the degradation of methylene blue (MB) dye and antibiotic tetracycline (TC) solution. The morphological studies confirmed that the CuO was uniformly dispersed on the CuCr₂O₄ matrix. The CuCr₂O₄/CuO nanocomposite showed high degradation efficiency of about 90% in the presence of H₂O₂ where the MB degradation reaction got completed in a mere 35 min and ~95% TC got degraded within 120 min.     

BSA mediated Ag@Bi2S3 composites: synthesis,characterization, photodegradation of mixed dyes via metal-semiconductor interface,antimicrobial and antioxidant activities

Nowadays, the development of metal-metal sulfide interface semiconductors using green approach is best material for the photocatalytic and biological applications. Here, we provided for the first time, an environmentally friendly route to fabricate bovine serum albumin (BSA) assisted Ag@Bi₂S₃ composites through a metal-metal sulphide interface via a simple hydrothermal method for the evaluation of photochemical and biological applications. The synthesized composites were characterized by UV–vis DRS, PL, XRD, TEM, and N₂ adsorption-desorption isotherms. The UV–vis DRS and PL spectra show that the obtained nano-sized Ag@Bi₂S₃ composite displays enhanced visible-light absorption and a decreased fluorescence emission compared to that of Bi₂S₃ nanorods (NRs). The photocatalytic performances of the synthesized composites were evaluated by the degradation of the single (RhB and MB) and mixed dye (RhB+MB) under sunlight irradiation. The results indicated that the Ag@Bi₂S₃ composite exhibits superior photocatalytic activity (98.38%) than that of individual Ag NPs and Bi₂S₃ NRs due to the synergistic effect of Ag and Bi₂S₃ nanophases in the Ag@Bi₂S₃ composite, which results in an effective charge separation, fast electron transfer from Ag to Bi₂S₃, and a low recombination of photo-induced electron-hole pairs. The Ag@Bi₂S₃ composite also has good recycling stability up to 5 cycles and its mechanism also investigated. The evaluation of reactive species during the photocatalytic reaction was also carried out. Further, the effects of Bi₂S₃ and Ag NPs on the antimicrobial and antioxidant activity of the resultant Ag@Bi₂S₃ composite were also systematically investigated.