查找使用阿拉丁产品的科研文献

Formic Acid-Regulated Defect Engineering in Zr-Based Metal-Organic Frameworks toward Fluorescence Sensor for Sensitive Detection of Chlortetracycline

Pei Jia,Qiushuang Wu,Boyang Sun,Li Wang

The elaborate defect-engineering of luminescent metal-organic frameworks (MOFs) allows them with enhanced sensing performance. A modulator-induced defect formation strategy is adopted in this paper, and the impact of the open-metal sites on sensing process is rationalized. It is demonstrated that the defect level can be tuned to a remarkable extent by controlling the amount of modulator. When a particular defect concentration is reached, the UiO-66-xFA can be acted as highly sensitive ratiometric fluorescence probes for chlortetracycline (CTE) determination with an ultralow detection limit of 9.9 n m . Furthermore, by virtue of the obvious variation in fluorescence chromaticity of probes from blue to yellow, a sensory hydrogels-based smartphone platform is proposed for visible quantitation of CTE by identifying the RGB values. A delicate device integrated with UV lamp and dark cavity has been developed for avoiding inconsistencies of ambient light and visual errors. Finally, the sensor obtains satisfactory results in the detection of actual seafood samples, with no significant differences from those of liquid chromatography−mass spectrometry. This approach anticipates a novel route to sensitize optical sensors through the design and synthesis of moderate defects in luminescent MOFs.

Synthesis of a novel acid-base bifunctional Zn/Ca–Zr catalyst for biodiesel application: Experimental and molecular simulation studies

Hewei Yu,Jichao Sun,Xiuxiu Chen,Bing Wang,Xiaohui Liang,Mingjie Gao,Hongyu Si

A novel acid-base bifunctional Zn/Ca–Zr catalyst has been synthesized successfully for biodiesel production from palm oil and acidified oil. The influence of synthetic factors on the catalytic activity of resulting Zn/Ca–Zr were discussed. Furthermore, the FAMEs yield was optimized to achieve the maximum value using the Taguchi approach. Results showed that the catalyst synthesized using a metal stoichiometric ratio of 4 : 4: 4, hydrothermal conditions, and activation temperature of 850 °C exhibited the best activity. The highest FAMEs yield was found to be 94.9% under the conditions of 5 wt% catalyst dosage, methanol/palm oil molar ratio of 20, and temperature of 170 °C at 3 h. The contribution percentage indicated that the methanol/oil molar ratio had the most significant effect on the FAMEs yield. Moreover, the Zn/Ca–Zr catalyst can catalyze the simultaneous esterification and transesterification of acidified palm oil with a 95.1% FAMEs yield and 93.3% acid reduction rate. And a 78.2% FAMEs yield can be maintained after four repeated cycles. Molecular simulations indicated the active site of Zn was more easily attacked by FFAs for esterification, while the active site of Ca was retained to adsorb methanol for transesterification, which explained the catalyst's acid-base bifunctional characteristics.

Rational Design of a Zr-MOF@Curli-Polyelectrolyte Hybrid Membrane toward Efficient Chemical Protection, Moisture Permeation, and Catalytic Detoxification

Jing Liu,Heguo Li,Bin Yan,Chao Zhong,Yue Zhao,Xuan Guo,Jinyi Zhong

Developing high-performance protective materials is important for soldiers and civilians who are exposed to the atmosphere of highly toxic chemical warfare agents (CWAs). Polyelectrolyte membranes are promising candidates with excellent chemical resistance and moisture permeability, but they cannot efficiently degrade CWAs. Here, we design and prepare a hybrid membrane through in situ growth of catalytically active zirconium-based metal–organic frameworks (Zr-MOFs) on a polyelectrolyte membrane mediated by biofilm-inspired curli nanofibers (CNFs). Superior to the bare polyelectrolyte membrane, the prepared MOF-808@CNF-PQ hybrid membrane exhibits improved rejection of the nerve agent simulant dimethyl methyl phosphonate (DMMP) vapor and permeation of the water vapor by 113 and 45%, respectively. The water/DMMP selectivity of the hybrid membrane reaches 498.6, approximately 13 times that of the commercial polyelectrolyte membrane Nafion 117. In addition, the hybrid membrane possesses appreciable catalytic activity for the hydrolysis of the nerve agent simulant dimethyl 4-nitrophenyl phosphate (DMNP) with a half-life of ∼38 min. Nanomechanical characterization results based on atomic force microscopy (AFM) techniques demonstrate the critical role of CNFs in mediating Zr-MOF nucleation and the dominant effect of electrostatic interactions on self-assembly of CNFs on polyelectrolyte base. It is also confirmed that the Zr-MOF toppings serve as the key components in physically adsorbing and chemically degrading the DMNP molecules through multiple strong intermolecular interactions. Our work offers a rational strategy to develop advanced membranes toward efficient chemical protection, moisture permeation, and catalytic detoxification against CWAs.

Direct grafting synthesis of bi-functional Zr–Al-MWW zeolites and their catalytic characteristics in Lewis-Brønsted cascade reaction

Yanghuan Huang,Haocheng Zhang,Lou Gao,Tianlan Yan,Yueer Yan,Yahong Zhang,Yi Tang

A series of Zr–Al-MWW zeolites with different Zr state and layer-stacking structure are successfully synthesized via direct grafting zirconocene dichloride onto the external silanols of three kinds of MWW zeolites, i.e. MCM-22 with multilayered structure, ITQ-2 (through layer delaminated route) and OL-MWW (by direct hydrothermal synthesis) with oligolayered structure. The structure, porosity and state of grafted Zr species are distinctly different among the three Zr–Al-MWW zeolites. Zr-OL-MWW possesses the highest content of single Zr atoms with an ideal micro-meso-macro pore system, while Zr-MCM-22 and Zr-ITQ-2 contain two kinds of Zr species (ZrO 2 clusters and single Zr atoms) coexisting in various proportions. The high dispersion of single Zr atoms on OL-MWW can be assigned to the large amount of external silanols of OL-MWW. The as-prepared three bi-functional Zr–Al-MWW zeolites are used for the cascade Meerwein-Ponndorf-Verley (MPV) reduction and etherification (ETH) reaction. Among them, Zr-OL-MWW shows dramatically higher conversion of cinnamaldehyde and yield of 1-cinnamyl 2-propyl ether than Zr-MCM-22 and Zr-ITQ-2, owing to the higher catalytic activity of Lewis acid centers from single Zr atoms, as well as more integrated framework Al sites as Brønsted acid centers with good accessibility. This study offers a simple and efficient strategy to construct Lewis-Brønsted acidic zeolites with exposed heteroatom sites and integrated framework structure, which will provide especial potential in the catalytic conversion of macromolecules.

Defect-engineered MOF-808 with highly exposed Zr sites as highly efficient catalysts for catalytic transfer hydrogenation of furfural

Qiuju Fu,Dandan Liu,Weijing Niu,Shuo Zhang,Ruihua Chen,Yujia Wang,Pengze Zhao,Huimin Jiang,Yanchao Zhao,Lingzhi Yang,Liting Yan,Haiyan Wang,Xuebo Zhao

The highly efficient production of furfuryl alcohol (FFA) from biomass-derived furfural (FFR) is attracting increasing attention due to its wide application in the production of value-added chemicals. Zr-based MOF-808 is promising for liquid catalytic transfer hydrogenation (CTH) of FFR to FFA in terms of possessing a great number of Lewis-acid sites. Herein, a series of defective MOF-808 (D x -MOF-808) samples were prepared via a competitive coordination-removal strategy by modulating with benzoic acid (HBC). HBC was introduced as the temporary ligand for competing with formal ligand 1,3,5-benzenetricarboxylic acid (H 3 BTC) to coordinate with metal clusters and then it was removed with methanol to obtain the D x -MOF-808. The results showed that HBC serves not only as a temporary ligand participating in the synthesis of MOF-808 to obtain defective structure but also as a modulator controlling the particle size by terminating the growth of crystals. By changing the amount of HBC addition, the degree of ligand deficiency and the number of exposed Zr sites can be well regulated. Especially, excellent performance of FFR conversion (99%), FFA selectivity (94.4%) and FFA formation rate (48.6 mmol·g −1 ·h −1 ) was achieved over D 40 -MOF-808 sample with 2-propanol as a hydrogen donor under mild conditions (90 °C, 2 h), ranking it the best among the reported catalysts. Detailed characterizations proved that the high activity of D 40 -MOF-808 was jointly influenced by the high surface area, the high content of exposed Zr metal sites and ligand deficiency.

Enhanced strain of (Ba, Ca)(Ti, Zr, Sn)O3 ferroelectrics with multiphase polar nanoregions coexistence and BO6 octahedral rotation

Qiong Li,Hao Qian,Tianyang Zheng,Xiaoyuan Sun,Yunfei Liu,Yinong Lyu

The cation displacement closely related to the local symmetry and corner-connected oxygen octahedral rotation are the structural origin of macroscopic properties in ABO 3 perovskite oxides. This work describes in detail the relationship between microstructure and macroscopic properties in 0.78BT-0.12CT-0.1BZS ceramic, which achieves the enhanced strain of 0.19 % with a hysteresis of 6.56 %. The atomic level structure is revealed by aberration corrected scanning transmission electron microscope (AC-STEM). The AC-STEM HAADF images reveal the coexisting of polar nanoregions with O and T symmetries. Such a microstructure has a lower energy barrier, facilitating dynamic polarization rotation flexibly under external stimuli. The AC-STEM ABF image reveals the existence of the BO 6 octahedral rotation, with rotation patterns of the a 0 b 0 c 0 and a - b + c - , and rotation angles are quantitatively measured. The BO 6 octahedral rotation and cation displacement are found to be consistent, the greater octahedral rotation with greater cation displacements. These results have important implications for understanding the structural origin of the excellent properties in ferroelectrics .

Ferrocene-boosting Zr-MOFs for efficient photocatalytic CO2 reduction: A trade-off between enhancing LMCT and frustrating Lewis acid

Li Xia,Wenxi Zhou,Yifan Xu,Zhengqiang Xia,Xinzhi Wang,Qi Yang,Gang Xie,Sanping Chen,Shengli Gao

The introduction of rich-electron ligands is a promising strategy to improve the ligand-to-metal charge transfer (LMCT) ability of metal–organic frameworks (MOFs) for efficient photocatalytic CO 2 reduction reactions (CO 2 RR), while the resulting impaired Lewis acid sites go against stable bonding with CO 2 and hinder the electron transfering to CO 2 . It is thus the key to search a trade-off between increasing LMCT and frustrating Lewis acid. Herein, the ferrocene (Fc) modified UiO-66 series MOFs, NH 2 -UiO-66-Fc, have been prepared to optimize LMCT for boosting CO 2 RR through a simple solvent-assisted ligand incorporation (SALI) method. Theoretical calculation and systematic experiments, including photoelectrochemical measures, in situ electron paramagnetic resonance, fluorescence probe analysis and X-ray photoelectron spectroscopy indicate that with increasing Fc content, the LMCT energy of MOFs significantly decreases from 2.66 to 2.10 eV based on the established electron transfer double-channel mechanism, while the Lewis acidity of Zr sites reduces with the CO 2 adsorption energy ( E ad ) ranging from −1.061 to −0.632 eV. Through introducing an optimal Fc content, NH 2 -UiO-66-Fc (2.0) integrating satisfactory LMCT ability and Lewis acidity shows superior photocatalytic CO 2 RR performance (CO yield: 90.65 μmol·g −1 ·h −1 ), about 13 times higher than that of the unmodified MOF and superior to most reported pristine MOF photocatalysts. DFT calculation demonstrates that the excellent performance of NH 2 -UiO-66-Fc (2.0) is attributed to the lowest energy barrier of 1.50 eV for the rate-limiting step of *COOH formation. In this work, such a simple post-modification strategy for facilitating the whole electron transfer path of photocatalytic CO 2 RR will provide a new way to construct high-performance MOFs-based CO 2 RR photocatalysts.

Effect of the Zr promoter on precipitated iron-based catalysts for high-temperature Fischer–Tropsch synthesis of light olefins

Yi Yang,Weixin Qian,Haitao Zhang,Zhonghao Han,Hongfang Ma,Qiwen Sun,Weiyong Ying

FeMnxZr and FeMnxZr2Na catalysts prepared by coprecipitation and impregnation methods were applied to investigate the promoting effects of Zr on iron-based catalysts for high-temperature Fischer–Tropsch synthesis (HTFT). Ar physisorption and TEM demonstrated that Zr-promoted catalysts have a larger BET surface area and larger pore volume, which are more conducive to the distribution of active phases. Zr promoted the dispersity of iron particles and reduced the grain size of iron particles, resulting in the improvement of the FTS activity. The CO-TPD and MES results revealed that the introduction of Zr promoted the dissociative adsorption of CO, thereby promoting the formation of the active phase χ-Fe5C2 while suppressing the formation of ε′-Fe2.2C and further improving the FTS activity and the selectivity to C2=–C4= in the hydrocarbon distribution. However, the addition of an excessive amount of Zr caused the excess ZrO2 to cover the surface of the active site, inhibiting the CO dissociative adsorption and the formation of χ-Fe5C2, resulting in a decrease in the CO conversion and the selectivity to C2=–C4=. The XPS and H2-TPR results proved the interaction between Fe2O3 and ZrO2. And the Fe–ZrO2 interaction inhibited the coke deposition and aggregation of the Fe species, as confirmed by XRD and TEM, respectively. The FeMn5Zr2Na catalyst exhibited the highest C2=–C4= selectivity of 34.4% at a CO conversion of 96.3%. And FeMn5Zr2Na displayed the highest production of light olefins (441.6 g h−1 kgCat−1), which was significantly higher than FeMn2Na (162.2 g h−1 kgCat−1).

Zr-MOF-Induced Smart Accumulation Enables Surface-Enhanced Raman Spectroscopic Detection of Dioxin at ppt Level in Food Samples

Jie Cheng,Bo-en Li,Jinghui He,Peilong Wang

The fast and economical detection of trace polychlorinated dibenzo-p-dioxins (PCDDs) in food samples by current mass spectrum-based methods is hindered by tedious sample preparation and bulky & expensive analytical instruments. Surface-enhanced Raman spectroscopy (SERS) successfully detects many organic pollutants in foods but not dioxins because the employed metal nanoparticles weakly adsorb hydrophobic PCDDs. Herein, we report the detection of PCDDs in milk with SERS for the first time using a bifunctional substrate consisting of Au nanoparticles embedded in a zirconium-based metal–organic framework shell (AuNP/Zr-MOF). 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), as the most toxic PCDD, is detected as low as 1.2 parts per trillion (ppt) in real milk samples with massive interfering substances in 30 min, which is the lowest among all reported methods. The aromatic rings of Zr-MOF promote the smart accumulation of TCDD through π–π interactions, and Au–Cl interactions drive TCDD onto Au surfaces. Zr-MOF shells with pore sizes of 12.7 and 20 Å block the accessibility of larger interfering molecules. A one-step apparatus and protocol are established to be superior to traditional methods in terms of time and cost. This work provides new insight into a rational screening method for the detection of persistent organic pollutants in a real sample matrix.

Boosting Antibacterial Photodynamic Therapy in a Nanosized Zr MOF by the Combination of Ag NP Encapsulation and Porphyrin Doping

Bao-Xuan Xie,Hai-Shuang Wang,Hui-Qian Zheng,Jin Xu,Li Chen,Fang-Zhong Zhang,Yu-Lin Wang,Zu-Jin Lin,Rong-Guang Lin

Antibacterial photodynamic therapy (aPDT) is regarded as one of the most promising antibacterial therapies due to its nonresistance, noninvasion, and rapid sterilization. However, the development of antibacterial materials with high aPDT efficacy is still a long-standing challenge. Herein, we develop an effective antibacterial photodynamic composite UiO-66-(SH)2@TCPP@AgNPs by Ag encapsulation and 4,4′,4″,4‴-(porphine-5,10,15,20-tetrayl)tetrakis(benzoic acid) (TCPP) dopant. Through a mix-and-match strategy in the self-assembly process, 2,5-dimercaptoterephthalic acid containing –SH groups and TCPP were uniformly decorated into the UiO-66-type framework to form UiO-66-(SH)2@TCPP. After Ag(I) impregnation and in situ UV light reduction, Ag NPs were formed and encapsulated into UiO-66-(SH)2@TCPP to get UiO-66-(SH)2@TCPP@AgNPs. In the resulting composite, both Ag NPs and TCPP can effectively enhance the visible light absorption, largely boosting the generation efficiency of reactive oxygen species. Notably, the nanoscale size enables it to effectively contact and be endocytosed into bacteria. Consequently, UiO-66-(SH)2@TCPP@AgNPs show a very high aPDT efficacy against Gram-negative and Gram-positive bacteria as well as drug-resistant bacteria (MRSA). Furthermore, the Ag NPs were firmly anchored at the framework by the high density of –SH moieties, avoiding the cytotoxicity caused by the leakage of Ag NPs. By in vitro experiments, UiO-66-(SH)2@TCPP@AgNPs show a very high antibacterial activity and good biocompatibility as well as the potentiality to promote cell proliferation.

Mixed matrix membrane for enhanced Ethanol/Water pervaporation separation by incorporation of hydrophilic Zr-MOF NU-906 in chitosan

Huayan Fu,Ruiwen Luo,Panpan Liu,Shuning Yu,Qinglei Xing,Peng Bai,Xianghai Guo,Jiafei Lyu

Conquering the trade-off between selectivity and permeability is crucial for efficient ethanol dehydration. The sophisticated metal–organic frameworks (MOFs) have proven their potential as membrane fillers despite of the limited research on few frameworks. Herein, in order to achieve enhanced water permselectivity, hydrophilic zirconium-based NU-906 nanoparticles were incorporated into chitosan (CS) to fabricate NU-906/CS mixed matrix membranes (MMMs) for alcohol dehydration. The introduction of NU-906 brought excellent water affinity and structural stability to the hybrid membranes confirmed by the water contact angle and swelling resistance tests. Benefiting from the hydrophilicity and the ordered porosity of the incorporated NU-906, simultaneously enhanced water selectivity and permeability have been achieved on the hybrid membranes. The optimum membrane with 5.0 wt% NU-906 exhibited a high flux of 1086 g/(m 2 ·h) and an excellent separation factor of 2651 for 90 wt% ethanol dehydration at 76   ℃. This research has expanded the range of MOFs available for the fabrication of MMMs and provided new options for organic solvent pervaporation dehydration.

Simultaneous Electrochemical Detection of Co-Existing Dihydroxybenzene Isomers Using Porphyrin Zr Metal-Organic Frameworks/β-cyclodextrin/Pencil Graphite Electrode

Siyi Yang,Shangming Wu,Juan Liu,Huanbao Fa,Mei Yang,Changjun Hou