石墨相氮化碳量子点的简易水热制备和荧光性能

本文以线状石墨相氮化碳(Lg-CN)为原料,在无需强酸加入的情况下,利用简单的纯水中的水热反应成功制得了氮化碳量子点(CN QDs),并利用傅里叶变换红外光谱、X射线粉末衍射、透射电镜、X射线光电子能谱等对所得量子点的形貌和结构进行了表征,进而解释了量子点的形成机理;利用紫外-可见吸收光谱和荧光光谱对其光学性质进行了研...     

石墨相氮化碳量子点的制备及应用的研究进展

近年来,石墨相氮化碳(g-C3N4)因其稳定的物理化学性能和良好的生物相容性而受到研究者关注。与块体g-C3N4相比,石墨相氮化碳量子点(g-CNQDs)尺寸更小、荧光效率更高,且具有量子限域效应,因此拥有特殊的理化性质与更好的光催化性能。本文主要从g-CNQDs的制备策略和应用展开讨论,着重综述了微波辅助法、低温固相法、热化学腐蚀法和电化学刻蚀法制备g-CNQDs,以及g-CNQDs在催化剂、离子检测、生物传感与诊疗等领域的最新应用研究进展;指出了目前g-CNQDs在性质、制备和应用等研究方面的重点和难点;最后对g-CNQDs存在的问题和未来的发展方向作出了展望。     

Synthesis of UiO-66 with addition of HKUST-1 for enhanced adsorption of RBBR dye

Toxic dye removal, one of the most serious and common industrial pollutants released into natural water, is a critical issue for modern civilization. In this study, a series of UiO-66 composites was synthesized with addition of HKUST-1 using solvothermal method, which was used to remove RBBR dye. The structure, morphology and surface area of the composites were studied by several analyses. HK(5)/UiO-66 possessed a specific surface area of 557.63 m²/g and showed an adsorption capacity of 400 mg/g, higher than that of UiO-66 (261.92 mg/g) with a contact time of 50 min. Several adsorption parameters that influenced RBBR removal efficiency were investigated, such as pH, initial dye concentrations, and temperature. All the composites followed pseudo-first order kinetics and Langmuir isotherm adsorption. Moreover, the adsorption process occurred exothermically and spontaneously, indicating that the adsorption process was advantageous in terms of energy. The possible adsorption mechanism and cost analysis of the adsorbent were also studied in detail.     

On the HKUST-1/GO and HKUST-1/rGO Composites: The Impact of Synthesis Method on Physicochemical Properties

The chemical stability and adsorptive/catalytic properties of the most widely studied metal–organic framework (MOF), which is HKUST-1, can be improved by its combination with graphene oxide (GO) or reduced graphene oxide (rGO). The chemistry of GO or rGO surfaces has a significant impact on their interaction with MOFs. In this work, we demonstrate that GO and rGO interaction with HKUST-1 influences the morphology and textural properties but has no impact on the thermal stability of the final composites. We also show that synthesis environment, e.g., stirring, to some extent influences the formation of HKUST-1/GO and HKUST-1/rGO composites. Homogeneous samples of the sandwich-type composite can be obtained when using reduced graphene oxide decorated with copper (Cu/rGO), which, owing to the presence of Cu sites, allows the direct crystallisation of HKUST-1 and its further growth on the graphene surface. This work is the first part of our research on HKUST-1/GO and HKUST-1/rGO and deals with the influence of the type of graphene material and synthesis parameters on the composites’ physicochemical properties that were determined by using X-ray diffraction, scanning and transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis.     

金属有机骨架HKUST-1及其衍生材料在催化中的应用进展

金属有机骨架材料(MOFs)作为异相催化剂受到了日益广泛的关注。在众多经典MOFs结构中,HKUST-1及其衍生材料是研究最多的类型之一。HKUST-1具有原料简单、易于合成、结构稳定、孔隙率高等多种优点,在异相催化领域中具有广阔的应用前景。已有多种HKUST-1相关材料被用作催化剂,包括HKUST-1本身、缺陷型结构、负载活性客体分子的复合型材料以及HKUST-1衍生的多孔碳纳米材料等。本文围绕HKUST-1作为催化剂的结构设计以及在不同催化反应中的应用展开总结与介绍,以期为相关MOFs材料的设计和催化研究提供一定参考。     

An Efficient Templating Approach for the Synthesis of Redispersible Size‐Controllable Carbon Quantum Dots from Graphitic Polymeric Micelles

Access to high‐quality, easily dispersible carbon quantum dots (CQDs) is essential in order to fully exploit their desirable properties. Copolymers based on N‐acryloyl‐D ‐glucosamine and acrylic acid prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization are self‐assembled into micelle‐like nanoreactors. After a facile graphitization process (170 °C, atmospheric pressure), each micellar template is transformed into a CQD through a 1:1 copy process. These high‐quality CQDs (quantum yield=22 %) with tunable sizes (2–5 nm) are decorated by carboxylic acid moieties and can be spontaneously redispersed in water and polar organic solvents. This preparation method renders the mass production of multifunctional CQDs possible. To demonstrate the versatility of this approach, CQDs hybridized TiO₂ nanoparticles with enhanced photocatalytic activity under visible‐light have been prepared.     

Carbon Dots for Carbon Dummies: The Quantum and The Molecular Questions Among Some Others

Carbon Dots (CDs) are carbon nanoparticles which were discovered in 2004. Despite two decades of intensive work from the scientific community and a colossal amount of gathered experimental data, no definitive consensus exists to date on several key aspects such as the actual definition of CDs and the origin of their emissive properties. This review proposes a critical evaluation of these fundamental questions. Lay persons will also find here an alternative introduction to the CDs domain, including synthetic strategies, photophysical properties, as well as challenges and outlook of this exciting new area.     

溶剂热插层法制备荧光石墨相氮化碳量子点及其在Fe3+检测中的应用

利用溶剂热法, 基于氢氧化钾的插层作用制备了荧光氮化碳量子点(g-C₃N₄ QDs). 所获得的氮化碳量子点具有良好的水溶性和荧光稳定性. 透射电子显微镜(TEM)照片显示, 氮化碳量子点的粒径约为2.3 nm; X射线光电子能谱(XPS)和红外光谱(FTIR)结果表明, 氮化碳量子点表面存在大量的亲水基团; 荧光发射光谱(PL)结果表明, 氮化碳量子点具有激发波长依赖性. 基于三价铁离子(Fe³⁺)对荧光氮化碳量子点荧光的猝灭现象, 构建了一种用于检测Fe³⁺的荧光传感器, 在Fe³⁺浓度为5~100 μmol/L范围内, 检测体系表现出良好的线性关系, 检出限约为0.5 μmol/L, 实现了对Fe³⁺的高效、 灵敏、 选择性检测.     

以金属有机骨架材料HKUST-1为模板制备多孔聚苯胺电极及其超级电容器性能研究

以涂敷在碳布基体上的金属有机骨架多孔材料HKUST-1为硬模板,使用单极脉冲法沉积聚苯胺制备了具有电活性的多孔复合电极Micro-PANI/CC,同时以空白碳布(Carbon Cloth,CC)为基体制备了聚苯胺电极PANI/CC,并研究、比较了它们的电化学电容器性能. 使用XRD、SEM分析了所得电极的结构,结果显示电极Micro-PANI/CC表面具有大量的纳米孔状结构. 在0.5 mol·L^-1硫酸为电解液的体系中测试了循环伏安、恒电流充放电、阻抗以及稳定性等特性,在扫速为2 mV·s^-1 时,电极Micro-PANI/CC和PANI/CC的比电容分别为895.6 F·g^-1和547.6 F·g^-1,在其它测试条件相同的情况下,前者的比电容保持在后者的1.64倍以上,且具有更好的倍率特性、更低的电阻和较好的稳定性等特点,说明这种以HKUST-1为模板形成的多孔聚苯胺更适于超级电容器电极材料.     

Graphitic Carbon Nitride Nanoribbons: Graphene‐Assisted Formation and Synergic Function for Highly Efficient Hydrogen Evolution

The development of new promising metal‐free catalysts is of great significance for the electrocatalytic hydrogen evolution reaction (HER). Herein, a rationally assembled three‐dimensional (3D) architecture of 1D graphitic carbon nitride (g‐C₃N₄) nanoribbons with 2D graphene sheets has been developed by a one‐step hydrothermal method. Because of the multipathway of charge and mass transport, the hierarchically structured g‐C₃N₄ nanoribbon–graphene hybrids lead to a high electrocatalytic ability for HER with a Tafel slope of 54 mV decade^?1, a low onset overpotential of 80 mV and overpotential of 207 mV to approach a current of 10 mA cm^?2, superior to those non‐metal materials and well‐developed metallic catalysts reported previously. This work presents a great advance for designing and developing highly efficient metal‐free catalyst for hydrogen evolution.     

钨酸铋量子点和纳米片修饰石墨相氮化碳复合催化剂的制备及其可见光催化活性增强

利用超声-水热法、使用油酸钠辅助合成钨酸铋(Bi₂WO₆)量子点/纳米片修饰的石墨相氮化碳(g-C₃N₄)(Bi₂WO₆/g-C₃N₄)复合光催化剂。 通过X射线粉末衍射(XRD)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)、紫外可见漫反射光谱(UV-Vis DRS)、N₂吸附-脱附等技术手段获得Bi₂WO₆/g-C₃N₄催化剂的组成、结构和光吸收性能,分析合成机理。 以罗丹明B(RhB)水溶液为模拟污染物,考察Bi₂WO₆/g-C₃N₄复合催化剂的可见光催化活性。 结果表明:g-C₃N₄和Bi₂WO₆的质量比为3:7的Bi₂WO₆/g-C₃N₄-30具有最有效的异质界面,电化学阻抗和光电流测试结果显示该催化剂的光生载流子传输速率快、复合率低,可见光照射120 min对RhB的降解率达到95.8%;通过活性物质捕捉实验获知光生空穴是光催化反应中的主要活性物质,分析异质界面对光催化活性的影响,进而提出光催化反应机理。     

Rhodium‐Catalyzed Ketone Methylation Using Methanol Under Mild Conditions: Formation of α‐Branched Products

The rhodium‐catalyzed methylation of ketones has been accomplished using methanol as the methylating agent and the hydrogen‐borrowing method. The sequence is notable for the relatively low temperatures that are required and for the ability of the reaction system to form α‐branched products with ease. Doubly alkylated ketones can be prepared from methyl ketones and two different alcohols by using a sequential one‐pot iridium‐ and rhodium‐catalyzed process.     

Milk-Derived Carbon Quantum Dots: Study of Biological and Chemical Properties Provides Evidence of Toxicity

Carbon dots (CDs) are carbon-based zero-dimensional nanomaterials that can be prepared from a number of organic precursors. In this research, they are prepared using fat-free UHT cow milk through the hydrothermal method. FTIR analysis shows C=O and C-H bond presence, as well as nitrogen-based bond like C-N, C=N and –NH₂ presence in CDs, while the absorption spectra show the absorption band at 280 ± 3 nm. Next, the Biuret test was performed, with the results showing no presence of unreacted proteins in CDs. It can be said that all proteins are converted in CDs. Photo luminance spectra shows the emission of CDs is 420 nm and a toxicity study of CDs was performed. The Presto Blue method was used to test the toxicity of CDs for murine hippocampal cells. CDs at a concentration of 4 mg/mL were hazardous independent of synthesis time, while the toxicity was higher for lower synthesis times of 1 and 2 h. When the concentration is reduced in 1 and 2 h synthesized CDs, the cytotoxic effect also decreases significantly, ensuring a survival rate of 60–80%. However, when the synthesis time of CDs is increased, the cytotoxic effect decreases to a lesser extent. The CDs with the highest synthesis time of 8 h do not show a cytotoxic effect above 60%. The cytotoxicity study shows that CDs may have a concentration and time–dependent cytotoxic effect, reducing the number of viable cells by 40%.     

反胶束法合成Cd1-xMnxS量子点及其发光性能研究

应用反胶束法制备了稀磁半导体Cd1-xMnxS量子点.量子点的大小可通过改变ωo值(wo=[水]/[表面活性剂])来控制.高分辨透射电镜的分析结果表明,量子点呈单分散性,是几乎没有缺陷的单晶体.量子点的大小约为4.8～6nm,随wo值增大而增大.电子能谱(EDS)测定结果表明,Mn2+离子在量子点中的摩尔分数为1.5%.由电子自旋共振(ESR)分析确定一部分Mn2+离子取代Cd2+离子位置而位于晶格,另一部分Mn2+离子位于Cd1-xMnxS的表面或间隙位置.吸收光谱显示,随着量子点变小,吸收带边发生蓝移,显示明显的量子尺寸效应.光致荧光光谱分析表明,发光峰属于Mn2+的4T1-6A1跃迁,而且随着ωo和粒径的增大,发光峰从2.26,2.10,2.05eV红移到1.88eV;其发光峰偏离2.12eV,主要是由于Mn2+离子位于扭曲的四面体晶体场所致.     

研究型综合化学实验设计:碳量子点的制备及其在叶酸检测中的应用

以高校创新型人才培养为目标,设计了一个研究型综合化学实验。以柠檬酸和尿素为原料,通过水热法制备了发射强烈蓝色荧光的碳量子点,表征了其紫外-可见吸收光谱和荧光光谱,进一步研究了该碳量子点在叶酸的检测中的应用。本实验涉及纳米材料制备、表征及应用相关知识,适合作为高年级本科生的研究型综合化学实验,有助于激发学生的研究兴趣和培养学生的科研思维。     

AgIn5S8/碳量子点/ZnIn2S4的多途径电子迁移与光催化性能

首先,借助碳量子点(CQDs)的上转换光致发光(UCPL)特性对ZnIn₂S₄进行了表面改性,再结合离子交换法制备了复合材料AgIn₅S₈/CQDs/ZnIn₂S₄。采用X射线衍射(XRD)、X射线光电子能谱(XPS)、紫外可见漫反射吸收光谱(UV-Vis DRS)、扫描电镜(SEM)、透射电镜(TEM)、氮气吸附-脱附、光致发光(PL)和电化学阻抗(EIS)等测试手段对复合材料的组成、结构、形貌以及表面物理化学性质等进行了表征。结果表明,该复合材料中不同组分间的协同作用导致其呈现宽光谱响应(250～800 nm)。与对比体系相比,复合材料AgIn₅S₈/CQDs/ZnIn₂S₄表现出明显增强的光电流密度,更小的电荷转移阻抗,较长的光生载流子寿命。以甲基橙为模型分子,在不同光源作用下进行的光催化活性研究结果显示,AgIn₅S₈...     

Composites of Anthraquinone Dyes@HKUST-1 with Tunable Microstructuring: Experimental and Theoretical Interaction Studies

The metal–organic framework (MOF) HKUST-1 was employed as an interaction matrix for fundamental loading studies of anthraquinone dyes. Chosen dyes were alizarin (A), alizarin S (AS), disperse blue 1 (B1), disperse blue 3 (B3), disperse blue 56 (B56) and purpurin (P). All materials were characterized by XRD, FTIR, TGA and SEM. Hence the interaction of dyes with the framework was characterized by theoretical–experimental differential analysis. One-pot loading strategy resulted in more efficient scavenging of dyes, and reached 100 % for B56 using 50 mg L⁻¹. SEM revealed important microstructural changes, the smaller crystals ranged 0.8–3 μm in size and almost all composite sizes were from this to higher values, reaching 70 μm, with varying shapes. Two composites were larger in size range (about 2500–1000 μm), and were shaped as rods, octahedrons and coffin lids. Indeed, the microstructure could be modulated depending on preparation conditions and type of loaded dye. For the higher loading series, N₂ adsorption and XPS experiments were carried on to further evidence dye–MOF interactions. Ab initio prediction of structural properties for A@HKUST-1 and P@HKUST-1 were obtained by means of solid-state CRYSTAL14 code at the PBE0 level of theory. Computed findings evidenced two O→Cu coordinative bonds, one from O-ketone and the other from O-phenolate moiety as main interactions towards CuNET centers.     

Benzyltriphenylphosphonium Chlorochromate: A Mild and Novel Reagent for Oxidation of Benzylic and Allylic Alcohols Under Non-Aqueous and Aprotic Conditions or Microwave Conditions

This paper describes the oxidation of benzylic and allylic alcohols under non-aqueous and aprotic conditions or microwave conditions using benzyltriphenylphosphonium chlorochromate (1) PhCH₂PPh₃CrO₃.HCl which has been prepared by mixing an aqueous solution of benzyltriphenylphosphonium chloride with CrO₃ in 6 N HCl at room temperature. This reagent is stable orange powder which may be stored for months without loss of its activity. This compound is readily soluble in organic solvents such as acetonitrile, chloroform and dichloromethane and slightly soluble in carbon tetrachloride, ether and hexane. the oxidation under microwave conditions is much more faster.     

Nitrogen-Doped Carbon Quantum Dots for Biosensing Applications: The Effect of the Thermal Treatments on Electrochemical and Optical Properties

The knowledge of the ways in which post-synthesis treatments may influence the properties of carbon quantum dots (CDs) is of paramount importance for their employment in biosensors. It enables the definition of the mechanism of sensing, which is essential for the application of the suited design strategy of the device. In the present work, we studied the ways in which post-synthesis thermal treatments influence the optical and electrochemical properties of Nitrogen-doped CDs (N-CDs). Blue-emitting, N-CDs for application in biosensors were synthesized through the hydrothermal route, starting from citric acid and urea as bio-synthesizable and low-cost precursors. The CDs samples were thermally post-treated and then characterized through a combination of spectroscopic, structural, and electrochemical techniques. We observed that the post-synthesis thermal treatments show an oxidative effect on CDs graphitic N-atoms. They cause their partially oxidation with the formation of mixed valence state systems, [CDs]⁰⁺, which could be further oxidized into the graphitic N-oxide forms. We also observed that thermal treatments cause the decomposition of the CDs external ammonium ions into ammonia and protons, which protonate their pyridinic N-atoms. Photoluminescence (PL) emission is quenched.