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1.
Metal-organic frameworks (MOFs) with abundant active sites, a class of materials composed of metal nodes and organic ligands, is widely used for photocatalytic degradation of pollutants. However, the rapid recombination of photoinduced carriers of MOFs limits its photocatalytic degradation performance. Herein, Ti 3C 2T x nanosheets-based NH 2-MIL-101(Fe) hybrids with Schottky-heterojunctions were fabricated by in situ hydrothermal assembly for improved photocatalytic activity. The photodegradation efficiencies of the NH 2-MIL-101(Fe)/Ti 3C 2T x (N-M/T) hybrids for phenol and chlorophenol were 96.36 % and 99.83 % within 60 minutes, respectively. The N-M/T Schottky-heterojunction duly transferred electrons to the Ti 3C 2T x nanosheets surface via built-in electric fields, effectively suppressing the recombination of photogenerated carriers, thereby improving the photocatalytic performance of NH 2-MIL-101(Fe). Moreover, the Fe-mixed-valence in the N-M/T led to improvement in the efficiency of the in situ generated photo-Fenton reactions, further enhancing the photocatalytic activity with more generated reactive oxygen species (ROS). The study proposes a highly effective removal of phenolic pollutants in wastewater. 相似文献
2.
Photocatalytic utilization of CO 2 in the production of value-added chemicals has presented a recent green alternative for CO 2 fixation. In this regard, three FeNbO 4/NH 2-MIL-125(Ti) composites of different mole ratios were synthesized, characterized using Powder X-ray diffraction (PXRD), UV–vis diffuse reflectance spectroscopy (UV-Vis DRS), Brunauer–Emmett–Teller (BET), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX). PXRD patterns confirm the co-existence of the parent components in the prepared composites. Moreover, the surface area increased as the mole percent of NH 2-MIL-125(Ti) in the composites increased due to the large surface area of NH 2-MIL-125(Ti). Prepared composites were investigated for the photocatalytic insertion of CO 2 into propylene oxide. FeNbO 4(75%)/NH 2-MIL-125(Ti) (25%) showed the highest percent yield of 52% compared to the other two composites. Results demonstrate the cooperative mechanism between FeNbO 4 and NH 2-MIL-125(Ti) and that the reaction proceeded photocatalytically. 相似文献
3.
Metal-organic frameworks (MOFs) constructed by ligands and metal clusters, have been considered as a promising material for photocatalytic water splitting. In this work, a solvent-assisted ligand exchange (SALE) method has been applied through partial reverse substitution of the ligand in NH 2-MIL-125 (Ti) by 1,4-dicarboxybenzene (BDC). This modification strategy can optimize the charge transfer dynamics together with the preserved light absorption, resulting in a 3.3 times higher hydrogen production rate compared to the pristine material under visible-light irradiation. This work broadens the field of ligand modifications of MOFs to boost the photocatalytic performance. 相似文献
4.
采用简单的溶剂热法制备金属有机框架化合物MIL-125(Ti)和NH_2-MIL-125(Ti)材料,并通过X射线衍射仪、扫描电子显微镜、傅氏转换红外线光谱分析仪和比表面积测试仪对所得样品进行表征。将2种材料修饰构建为石英晶体微天平传感器,测试其在11%~97%RH相对湿度范围内的湿度感测性能。实验结果表明,基于MIL-125(Ti)和NH_2-MIL-125(Ti)构建的传感器对湿度具有灵敏度高、重复性好、响应/恢复快等特点。相对于没有氨基修饰的MIL-125(Ti),NH_2-MIL-125(Ti)材料修饰的传感器对湿度表现出更高的响应性能。在环境湿度约52%时,NH_2-MIL-125(Ti)传感器对11%RH湿度响应值比MIL-125(Ti)湿度传感器的大57 Hz,说明氨基功能化对MIL-125(Ti)的湿敏性能有显著的增强作用。此外,通过Materials Studio模拟计算获得了水分子与MIL-125(Ti)及NH_2-MIL-125(Ti)作用的吸附焓,也证明氨基功能化对MIL-125(Ti)的湿度敏感性能具有增强作用。 相似文献
5.
Bi 2WO 6/TiO 2 heterojunction photocatalysts with two different microstructures were controllably fabricated via a facile two-step synthetic route. XRD, XPS, SEM, TEM, BET-surface, DRS, PL spectra, photoelectrochemical measurement (Mott-Schottky), and zeta-potential analyzer were employed to clarify structural and morphological characteristics of the obtained products. The results showed that Bi 2WO 6 nanoparticles/nanosheets grew on the primary TiO 2 nanorods. The TiO 2 nanorods used as a synthetic template inhibit the growth of Bi 2WO 6 crystals along the c-axis, resulting in Bi 2WO 6/TiO 2 heterostructure with one-dimensional (1D) morphology. The photocatalytic properties of Bi 2WO 6/TiO 2 heterojunction photocatalysts were strongly dependent on their shapes and structures. Compared with bare Bi 2WO 6 and TiO 2, Bi 2WO 6/TiO 2 composite have stronger adsorption ability and better visible light photocatalytic activities towards organic dyes. The Bi 2WO 6/TiO 2 composite prepared in EG solvent with optimal Bi:Ti ratio of 2:12 (S-TB2) showed the highest photocatalytic activity, which could totally decompose Rhodamine B within 10 min upon irradiation with visible light (λ > 422 nm), and retained the high photocatalytic performance after five recycles, confirming its stability and practical usability. The results of PL indicated that Bi 2WO 6 and TiO 2 could combine well to form a heterojunction structure which facilitated electron–hole separation, and lead to the increasing photocatalytic activity. 相似文献
6.
M‐doped NH 2‐MIL‐125(Ti) (M=Pt and Au) were prepared by using the wetness impregnation method followed by a treatment with H 2 flow. The resultant samples were characterized by powder X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), X‐ray absorption fine structure (XAFS) analyses, N 2‐sorption BET surface area, and UV/Vis diffuse reflectance spectroscopy (DRS). The photocatalytic reaction carried out in saturated CO 2 with triethanolamine (TEOA) as sacrificial agent under visible‐light irradiations showed that the noble metal‐doping on NH 2‐MIL‐125(Ti) promoted the photocatalytic hydrogen evolution. Unlike that over pure NH 2‐MIL‐125(Ti), in which only formate was produced, both hydrogen and formate were formed over Pt‐ and Au‐loaded NH 2‐MIL‐125(Ti). However, Pt and Au have different effects on the photocatalytic performance for formate production. Compared with pure NH 2‐MIL‐125(Ti), Pt/NH 2‐MIL‐125(Ti) showed an enhanced activity for photocatalytic formate formation, whereas Au has a negative effect on this reaction. To elucidate the origin of the different photocatalytic performance, electron spin resonance (ESR) analyses and density functional theory (DFT) calculations were carried out over M/NH 2‐MIL‐125(Ti).The photocatalytic mechanisms over M/NH 2‐MIL‐125(Ti) (M=Pt and Au) were proposed. For the first time, the hydrogen spillover from the noble metal Pt to the framework of NH 2‐MIL‐125(Ti) and its promoting effect on the photocatalytic CO 2 reduction is revealed. The elucidation of the mechanism on the photocatalysis over M/NH 2‐MIL‐125(Ti) can provide some guidance in the development of new photocatalysts based on MOF materials. This study also demonstrates the potential of using noble metal‐doped MOFs in photocatalytic reactions involving hydrogen as a reactant, like hydrogenation reactions. 相似文献
7.
CeO 2/Bi 2WO 6 heterostructured microsphere with excellent and stable photocatalytic activity for degradation tetracyclines was successfully synthesized via a facile solvothermal route. The photocatalytic experiments indicated that CeO 2/Bi 2WO 6 heterostructured microspheres exhibited enhanced photocatalytic activity compared to pure Bi 2WO 6 in both the degradation of tetracycline hydrochloride (TCH) and rhodamine B (RhB) under visible‐light irradiation. The 1CeO 2/2Bi 2WO 6 exhibited the best photocatalytic activity for degradation of TCH, reaching 91% after 60 min reaction. The results suggested that the particular morphological conformation of the microspheres resulted in smaller size and more uniform morphology so as to increase the specific surface area. Meanwhile, the heterojunction was formed by coupling CeO 2 and Bi 2WO 6 in the as‐prepared microspheres, so that the separation efficiency of photogenerated electrons and holes was dramatically improved and the lifetimes of charge carriers were prolonged. Hence, introduction of CeO 2 could significantly enhance the photocatalytic activity of CeO 2/Bi 2WO 6 heterostructured microspheres and facilitate the degradation of TCH. This work provided not only a principle method to synthesize CeO 2/Bi 2WO 6 with the excellent photocatalytic performance for actual produce, but also a excellent property of the photocatalyst for potential application in photocatalytic treatment of tetracyclines wastewater from pharmaceutical factory. 相似文献
8.
Metal–organic frameworks (MOFs) have been demonstrated to be desired candidates for sensing definite species owing to their tunable composition, framework structure and functionality. In this work, the NH 2-MIL-101 series was utilized for sensing specific amino acids. The results show that cysteine (Cys) can significantly enhance the fluorescence emission of NH 2-MIL-101-Fe suspended in water, while NH 2-MIL-101-Al exhibits the ability to sense lysine (Lys), arginine (Arg) and histidine (His) in aqueous media via turn-on fluorescence emission. Titration experiments ensure that NH 2-MIL-101-Fe and NH 2-MIL-101-Al can selectively and quantitatively detect these amino acids. The sensing mechanism was examined and discussed. The results of this study show that the metal centers in MOFs are crucial for sensing specific amino acids. 相似文献
9.
The electronic conductivity (EC) of metal–organic frameworks (MOFs) is sensitive to strongly oxidizing guest molecules. Water is a relatively mild species, however, the effect of H 2O on the EC of MOFs is rarely reported. We explored the effect of H 2O on the EC in the MOFs (NH 2) 2-MIL-125 and its derivatives with experimental and theoretical investigations. Unexpectedly, a large EC increase of 10 7 on H 2SO 4@(NH 2) 2-MIL-125 by H 2O was observed. Brønsted acid–base pairs formed with the −NH 2 groups, and H 2SO 4 played an important role in promoting the charge transfer from H 2O to the MOF. Based on H 2SO 4@(NH 2) 2-MIL-125, a high-performance chemiresistive humidity sensor was developed with the highest sensitivity, broadest detection range, and lowest limit of detection amongst all reported sensing materials to date. This work not only demonstrated that H 2O can remarkably influence the EC of MOFs, but it also revealed that post-modification of the structure of MOFs could enhance the influence of the guest molecule on their EC to design high-performance sensing materials. 相似文献
10.
Uniform Bi 2WO 6 spheres with high visible light activity were prepared via a solvothermal route. A variety of techniques including transmission electron micrographs (TEM), X-ray powder diffraction (XRD), N 2 adsorption, FT-IR spectra, and UV–Vis spectra were employed to characterize the structure of the Bi 2WO 6 materials so obtained. The results show that the sphere-like Bi 2WO 6 samples were successfully prepared. And, under the photocatalytic degradation of Rhodamine B, the samples demonstrated high activity, three times higher than that of a sample from the solid-state method. Moreover, the uniform structure made the sample easy to separate from the reaction solution, providing an intrinsic advantage to the normal Bi 2WO 6 samples. 相似文献
11.
Visible-light-driven heterostructure Ag/Bi2WO6 nanocomposites were prepared by transforming Ag+ ions into metallic Ag0 nanoparticles loaded on top of Bi2WO6 nanoplates under visible light irradiation for 1 h. XRD, XPS, SEM and TEM analyses indicated that spherical metallic Ag nanoparticles were uniformly dispersed on top of orthorhombic Bi2WO6 thin nanoplates. Rhodamine B (RhB) was used as a dye model for investigation of photocatalytic performance of Bi2WO6 nanoplates with different weight contents of Ag nanoparticles illuminated by visible radiation. In this research, 10% Ag/Bi2WO6 nanocomposites have the highest photocatalytic activity in the degradation of RhB at 94.21% within 210 min because of the rapid diffusion of electronic charge through the Schottky barrier between metallic Ag nanoparticles and Bi2WO6 thin nanoplates, good electrical conductivity of metallic Ag nanoparticles, inhibited recombination of charge carriers and enhanced photocatalytic activity of Ag/Bi2WO6 nanocomposites. Main active species of the photocatalysis and stability of the photocatalyst were also evaluated. 相似文献
12.
Bi 2WO 6 powder photocatalyst was prepared using Bi(NO 3) 3 and Na 2WO 4 as raw materials by a simple hydrothermal method at 150 °C for 24 h, and then calcined at 300, 400, 500, 600 and 700 °C for 2 h, respectively. The as-prepared samples were characterized with UV-visible diffuse reflectance spectra, fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and N 2 adsorption-desorption measurement. The photocatalytic activity of the samples was evaluated using the photocatalytic oxidation of formaldehyde at room temperature under visible light irradiation. It was found that post-treatment temperature obviously influenced the visible-light photocatalytic activity and physical properties of Bi 2WO 6 powders. At 500 °C, Bi 2WO 6 powder photocatalyst showed the highest visible-light photocatalytic activity due to the samples with good crystallization and high BET surface area. 相似文献
13.
Pd nanoparticles supported on Bi2WO6 nanoplates used for visible-light-driven photocatalyst were successfully synthesized by photoreduction deposition method under visible-light irradiation. Different analytical techniques including X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and photoluminescence spectroscopy revealed that face-centered cubic metallic Pd nanoparticles were uniformly loaded on top of orthorhombic Bi2WO6 nanoplates to form heterostructure Pd/Bi2WO6 nanocomposites. Photocatalytic activities of pure Bi2WO6 sample and heterostructure Pd/Bi2WO6 nanocomposites were studied through the photodegradation of rhodamine B (RhB) under visible-light irradiation. The photocatalytic efficiency of Bi2WO6 was increased to the highest by being loaded with 5 wt% Pd and then decreased by being loaded with 10 wt% Pd. The improved photocatalytic efficiency caused by high-efficiency diffusion and separation of photo-generated charge carriers was explained and can lead to superior photodegradation of RhB under visible-light irradiation. 相似文献
14.
利用水热法合成了Fe3+掺杂的三维分级纳米Bi2WO6,借助X射线衍射(XRD)、场发射扫描电镜(FE-SEM)、透射电镜(HRTEM)、能谱(EDS)、紫外可见漫反射(UV-Vis-DRS)等测试手段对所得样品的相组成、形貌和谱学特征进行了表征。选择罗丹明B为模型污染物研究所得样品在可见光下的催化活性。结果表明,Fe3+掺杂Bi2WO6为新颖的分级纳米结构,且Fe3+掺杂能有效提高Bi2WO6的光催化活性,Fe3+掺杂量对Bi2WO6活性的影响显著;实验结果还表明,所得Fe3+掺杂Bi2WO6催化剂的稳定性较好,易于回收。此外,还对Fe3+掺杂Bi2WO6的光催化活性增强机理进行了研究,缺电子的Fe3+作为电子捕获中心有利于促进光生电子-空穴对的分离,从而提高Bi2WO6的光催化活性。 相似文献
15.
利用水热法合成了Fe 3+掺杂的三维分级纳米Bi 2WO 6,借助X射线衍射(XRD)、场发射扫描电镜(FE-SEM)、透射电镜(HRTEM)、能谱(EDS)、紫外可见漫反射(UV-Vis-DRS)等测试手段对所得样品的相组成、形貌和谱学特征进行了表征。选择罗丹明B为模型污染物研究所得样品在可见光下的催化活性。结果表明,Fe 3+掺杂Bi 2WO 6为新颖的分级纳米结构,且Fe 3+掺杂能有效提高Bi 2WO 6的光催化活性,Fe 3+掺杂量对Bi 2WO 6活性的影响显著;实验结果还表明,所得Fe 3+掺杂Bi 2WO 6催化剂的稳定性较好,易于回收。此外,还对Fe 3+掺杂Bi 2WO 6的光催化活性增强机理进行了研究,缺电子的Fe 3+作为电子捕获中心有利于促进光生电子-空穴对的分离,从而提高Bi 2WO 6的光催化活性。 相似文献
16.
采用简单沉积-沉淀法合成了Bi 2WO 6@Bi 2MoO 6-xF 2x(BWO/BMO6-xF2x)异质结,借助XRD、XPS、TEM、SEM、EDS、UV-Vis-DRS、PC和EIS等测试技术对其组成、形貌、光吸收特性和光电化学性能等进行系统表征,并以模型污染物罗丹明B(RhB)的光催化降解作为探针反应来评价Bi 2WO 6@Bi 2MoO 6-xF 2x异质结的光催化活性增强机制。形貌分析表明,所得Bi 2MoO 6微球由大量厚度为20~50 nm的纳米片组成;FE-SEM和HR-TEM分析表明,尺寸约为10 nm的Bi 2WO 6量子点均匀沉积在Bi 2MoO 6-xF 2x微球表面,形成新颖的Bi 2WO 6@Bi 2MoO 6-xF 2x异质结;与纯Bi 2MoO 6或者Bi 2WO 6相比,1∶1Bi 2WO 6@Bi 2MoO 6-xF 2x异质结表现出更好的光催化活性和光电流性质,其对RhB光催化降解的表观速率常数分别为纯BMO和BWO的6.4和11.6倍。PC和EIS图谱分析表明,Bi 2WO 6量子点表面沉积显著提高Bi 2MoO 6-xF 2x光生电子/空穴的分离效率和迁移速率;活性物种捕获实验证明了·O 2-和h +是主要的活性物种。根据实验结果,探讨了F -掺杂和Bi 2WO 6量子点之间的协同效应对Bi 2MoO 6的光催化活性的影响机制。 相似文献
17.
采用简单沉积-沉淀法合成了Bi_2WO_6@Bi_2MoO_(6-x)F_(2x)(BWO/BMO_(6-x)F_(2x))异质结,借助XRD、XPS、TEM、SEM、EDS、UV-Vis-DRS、PC和EIS等测试技术对其组成、形貌、光吸收特性和光电化学性能等进行系统表征,并以模型污染物罗丹明B(Rh B)的光催化降解作为探针反应来评价Bi_2WO_6@Bi_2MoO_(6-x)F_(2x)异质结的光催化活性增强机制。形貌分析表明,所得Bi_2MoO_6微球由大量厚度为20~50 nm的纳米片组成;FE-SEM和HR-TEM分析表明,尺寸约为10 nm的Bi_2WO_6量子点均匀沉积在Bi_2MoO_(6-x)F_(2x)微球表面,形成新颖的Bi_2WO_6@Bi_2MoO_(6-x)F_(2x)异质结;与纯Bi_2MoO_6或者Bi_2WO_6相比,1∶1Bi_2WO_6@Bi_2MoO_(6-x)F_(2x)异质结表现出更好的光催化活性和光电流性质,其对RhB光催化降解的表观速率常数分别为纯BMO和BWO的6.4和11.6倍。PC和EIS图谱分析表明,Bi_2WO_6量子点表面沉积显著提高Bi_2MoO_(6-x)F_(2x)光生电子/空穴的分离效率和迁移速率;活性物种捕获实验证明了·O_2~-和h~+是主要的活性物种。根据实验结果,探讨了F-掺杂和Bi_2WO_6量子点之间的协同效应对Bi_2MoO_6的光催化活性的影响机制。 相似文献
18.
以五水合硝酸铋和二水合钨酸钠为原料,以十六烷基三甲基溴化铵(CTAB)为溴源,制备Br掺杂Bi 2WO 6,通过调节CTAB的含量,利用水热法制备了Br掺杂量不同的Bi 2WO 6催化剂。以抗生素环丙沙星、诺氟沙星作为污染物,测试Br掺杂Bi 2WO 6催化剂的光催化性能。结果表明,2%掺杂量(物质的量分数)的Bi 2WO 6相比于Bi 2WO 6的光催化降解性能最好。此外,通过X射线粉末衍射、红外光谱、扫描电镜、荧光光谱、X射线光电子能谱和拉曼光谱等一系列表征,对Br掺杂后催化剂的物相组成、微观形貌、光生电荷分离率和光学性质等进行分析。最后进行了自由基捕获实验并提出了可能的光催化机理。 相似文献
19.
A novel visible light-responsive homogeneous catalyst based on Bi 2WO 6 quantum dots (QDs-BWO)/Bi 2WO 6 nanosheets (N-BWO) was successfully fabricated through a simple hydrothermal method. A variety of techniques were employed to investigate the morphology, structure, and electronic properties of the samples. The photocatalytic performance of the QDs/N-BWO materials was investigated by monitoring the degradation of 4-chlorophenol and rhodamine B under visible light irradiation. The as-fabricated QDs/N-BWO materials showed higher photocatalytic activity than both QDs-BWO and N-BWO. The results reveal that the incorporation of the QDs improved the separation efficiency of electron-hole pairs, leading to enhanced photocatalytic activity. Moreover, the results of quenching experiments show that ·O 2– species played a major role in the degradation process. This work provides an important reference for the fabrication of homogeneous catalysts with high performance in the degradation of different types of pollutants. 相似文献
20.
In this work, an Ag-loaded octahedral Bi 2WO 6 photocatalyst has been successfully prepared by the hydrothermal method and photo deposition method. X-ray diffraction (XRD), energy dispersive analysis of X-ray (EDX), field-emission scanning electron microscopy (FE-SEM) and ultra-violet adsorption spectrum (UV-Vis) were employed for characterization of the composite photocatalyst. Furthermore, two different photocatalysts including the obtained Ag-loaded octahedral Bi 2WO 6 were employed here for photodegradation of model contaminated water of Orange II (OII). Results show that Ag-loaded Bi 2WO 6 photocatalyst exhibits superior photocatalytic properties compared to the undoped Bi 2WO 6. The reasons for improvement in photocatalytic activity of the Ag-loaded octahedral Bi 2WO 6 were also discussed. 相似文献
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