电化学方法调控荧光碳点的研究

作为零维碳基发光纳米材料,碳点是对现有发光纳米材料的重要补充. 精准控制粒径及表面结构对实现碳点的性质调控及其应用至关重要. 本文介绍了本课题组在利用电化学方法研究荧光碳点方面的进展. 重点展示了利用电化学方法实现对碳点粒径的控制,对表面氧化程度的调节以及对其发光机理的研究. 电化学方法可对只有几纳米厚度的材料表面进行有效的控制,可操作性强且经济环保. 通过对碳点的粒径及表面的调控,作者也进一步揭示了碳点的发光与表面结构的相关性. 这些工作为碳点的合成及其性质调控提供了可循的规律,有利于推动碳点在生物医生成像、传感检测、催化及能源转化等领域的应用.     

基于碳纳米材料的毛细管电色谱固定相研究进展

碳纳米材料由于其具有独特的纳米结构、大的比表面积、较强的热稳定性、良好的导电性以及较好的吸附性能等物理化学性质,因而在分析科学、生命科学、材料科学及环境科学等领域得广泛的应用.结合国内外最新文献,对近5年来碳纳米材料在毛细管电色谱新型固定相的制备研究方面进展进行了评述,包括毛细管电色谱的分类及分离机理、毛细管电色谱柱的制备方法和优缺点,碳纳米材料(石墨烯、碳纳米管、氧化石墨烯、还原氧化石墨烯、富勒烯)的结构性质及制备方法、碳纳米材料在毛细管电色谱柱固定相中的应用及作用机理等,并对其在色谱应用领域的方向进行了展望.     

掺杂碳点的制备及其应用研究进展

掺杂碳点因其丰富的制备手段、优良的光学性质以及良好的生物相容性,在生物检测、防伪、药物传输、光电器件等领域具有巨大的潜在应用空间,是极具发展潜力的炭基材料之一.近年来,如何提高碳点的发光效率、探索发光机理、拓展碳点新的应用方向引起广泛关注.本文综述了不同掺杂碳点的特性,总结了碳点在不同领域的应用,并且分析了碳点存在的问题.     

碳点的研究进展

碳点具有优良的光学特性、良好的生物相容性和低毒等优点,被广泛用于生物检测、药物传输和生物成像等领域,是极具发展潜力的碳基质材料.近年来,碳点的新型制备方法、性质探索及应用研究引起广泛关注.本文根据碳源和制备方法的不同,将碳点分为石墨烯纳米点和碳纳米点两类,综述了碳点的制备方法,剖析了碳点的发光机理,总结了碳点在生物传感、药物传输和生物成像中的应用;最后分析了碳点存在的问题及应对策略.     

氢氧化钾活化制备超级电容器多孔碳电极材料

具有高比表面积、良好导电性的多孔碳材料在超级电容器中有着广泛的应用前景. 大量的研究工作致力于通过物理或者化学手段合成并调控多孔材料的微观结构. 在众多多孔碳材料的制备方式中,氢氧化钾作为一种高效的活化剂,常用于制备具有良好孔径分布和高比表面积多孔碳电极材料. 本文主要结合作者课题组的研究工作,着重概述利用氢氧化钾活化sp²碳纳米材料制备多孔碳材料的机理过程、结构形貌的转变以及所得材料的电化学性能,希望对发展新型的高性能基多孔碳材料的超级电容器电极材料有所帮助.     

多色荧光碳点的制备新进展

碳点(碳量子点)是在紫外-可见光吸收区域具有有效吸收的、可多色发光的新型碳纳米材料,在生物医学、环境能源和催化领域有着重要的研究应用前景。但是,在过去的10年中,无论是自上而下还是自下而上的方法,所制备碳点的发光大部分集中在蓝光-橙光范围。最近,随着制备方法的改进,有多种方法制备出了红光或近红外发光的碳点。本文简述了近3年来各类代表性的制备碳点的方法,并主要介绍了红光或近红外发光碳点的制备新进展。     

碳点荧光探针的制备及其在食品分析中的应用

碳点作为一种新型荧光碳纳米材料,具有优良的光学性能和小尺寸特性,以及良好的生物相容性、低毒性以及易于实现表面功能化等特点,是潜在的可以代替传统半导体量子点等荧光探针的良好选择.基于其独特的荧光特性和高灵敏度,碳点荧光探针在食品分析领域具有很好的应用潜力.本文对近年来荧光碳点的研究进展进行了综述,简述碳点的性能并对碳点的制备方法进行总结对比,重点介绍了碳点荧光探针在食品分析领域的应用,对目前碳点应用的限制进行了分析,对其发展前景和展望.     

发光碳量子点的合成、性质和应用

基于碳量子点具有良好的水溶性、化学惰性、低毒性、易于功能化和抗光漂白性等优异性能,碳量子点和其它的碳纳米材料（如富勒烯、碳纳米管和石墨烯等）同样引起了研究者广泛的关注。 碳量子点可以通过很多较为廉价的一步法进行大规模的制备,包括化学氧化法、超声法、微波法和激光烧蚀法等。 本文主要介绍了不同碳量子点的合成方法,以及依赖于碳量子点尺寸和波长等性质的发光性能,并且讨论了碳量子点在生物成像、光催化、能量转换/储存、光电子、光限幅和传感器等方面的应用。     

碳纳米材料在修饰电极领域的应用

碳纳米材料具有良好的力学、电学及化学性能等特点,被人们广泛研究,特别是具有大比表面积、高的电导率和良好生物相容性的碳纳米管和石墨烯更是研究的热点,在电化学领域显示出独特的优势.采用碳纳米材料修饰的电极具有高灵敏度、高选择性及优良的媒介作用.主要阐述了碳纳米材料在修饰电极领域中的应用,从功能及应用上重点探讨了近年来碳纳米管、石墨烯、富勒烯、纳米金刚石等碳纳米材料在修饰电极领域的研究进展.     

电化学技术制备纳米材料研究的新进展

利用电化学方法制备与组装纳米材料是近年来发展起来的一项新技术.本文对电化学方法在纳米材料制备中的应用及其研究进展做了较为全面的概述,着重介绍了模板电化学法合成纳米材料、稳定剂保护下电化学还原法制备金属溶胶、电化学台阶边缘修饰法制备一维纳米材料以及脉冲超声电化学法制备纳米粒子,并对其应用前景做了展望.     

微波法制备纳米碳点反应机制与发光机理

为探讨微波法制备纳米碳点发光性质的影响规律与本质,采用微波加热法通过控制微波功率、反应时间以及pH值合成了一系列纳米碳点,并利用荧光激发光谱与发射光谱测试对纳米碳点的发光性质进行了表征,结合紫外吸收光谱与傅立叶红外光谱对反应产物官能团变化分析,最终揭示了微波加热过程中葡萄糖向纳米碳点转变的机制与发光机理。结果表明,采用微波法制备纳米碳点,当微波功率为560 W,反应时间为2.5 min时,获得纳米碳点发光性能最佳。当采用波长370 nm紫外光激发时,对应451 nm的蓝光发射强度最高。伴随纳米碳点溶液pH值从酸性变为碱性,纳米碳点最强发光峰的激发光波长由350 nm显著向高波长方向移动,且发光峰强度显著升高。紫外吸收光谱与傅立叶红外光谱显示反应过程中形成了多环芳香族碳氢化合物,表明微波加热过程中是葡萄糖单糖向多糖聚合并最终发生碳化的过程。不同pH值下纳米碳点发光性质的差异,源于对纳米碳点中C=C键与C=O键比例的调整,从而实现对纳米碳点的光学带隙宽度及激子束缚能等的综合调控。     

Hierarchically porous nitrogen-doped carbon foams decorated with zinc nanodots as high-performance sulfur hosts for lithium-sulfur battery

To prevent polysulfides from dissolution into electrolyte, we propose a novel and simple approach to nitrogen-doped carbon foams which contain hierarchically porous structure and are decorated with zinc nanodots through one-pot carbonization and activation process. These carbon foams, which serve as hosts for sulfur in lithium battery, can provide a conducting network and shorter diffusion length for Li-ions. Specially, the zinc nanodots derived from the carbothermal reaction of ZnCl₂ at high temperature can interact with sulfur/polysulfides by strong chemisorption. In addition, the zinc nanodots can also facilitate the conversion reaction between Li₂S_x (2 < x < 8) and Li₂S/Li₂S₂. Therefore, Zn@NCFs/S cathode presents high sulfur utility and large capacity.     

玛卡荧光碳点的合成及用于苦味酸的荧光检测

以玛卡为碳源,采用水热法制备荧光碳点。碳点水溶液在激发波长为315 nm时,最大荧光发射波长为425 nm。在玛卡荧光碳点的磷酸盐缓冲液(0.2 mol/L,pH 5.8)中,加入苦味酸,其荧光被猝灭,基于此建立了以玛卡荧光碳点为荧光探针测定苦味酸的方法。本方法检测苦味酸的线性范围为0.4~80 mmol/L,相关系数为0.9978,检出限为110 nmol/L(S/N=3),本方法线性范围宽、灵敏度高、响应快(2 min内),选择性和抗干扰能力良好。用于实际水样中苦味酸的检测,加标回收率为92.0%~110.0%,结果令人满意。     

Study on the Ultrahigh Quantum Yield of Fluorescent P,O‐g‐C3N4 Nanodots and its Application in Cell Imaging

Graphitic carbon nitride nanodots (g‐C₃N₄ nanodots), as a new kind of heavy‐metal‐free quantum dots, have attracted considerable attention because of their unique physical and chemical properties. Although various methods to obtain g‐C₃N₄ nanodots have been reported, it is still a challenge to synthesize g‐C₃N₄ nanodots with ultrahigh fluorescence quantum yield (QY). In this study, highly fluorescent phosphorus/oxygen‐doped graphitic carbon nitride (P,O‐g‐C₃N₄) nanodots were prepared by chemical oxidation and hydrothermal etching of bulk P‐g‐C₃N₄ derived from the pyrolysis of phytic acid and melamine. The as‐prepared P,O‐g‐C₃N₄ nanodots showed strong blue fluorescence and a relatively high QY of up to 90.2 %, which can be ascribed to intrinsic phosphorus/oxygen‐containing groups, and surface‐oxidation‐related fluorescence enhancement. In addition, the P,O‐g‐C₃N₄ nanodots were explored for cell imaging with excellent stability and biocompatibility, which suggest that they have great potential in biological applications.     

From Metal–Organic Framework to Intrinsically Fluorescent Carbon Nanodots

Highly photoluminescent carbon nanodots (CNDs) were synthesized for the first time from metal–organic framework (MOF, ZIF‐8) nanoparticles. Coupled with fluorescence and non‐toxic characteristics, these carbon nanodots could potentially be used in biosafe color patterning.     

Carbon nanodots as fluorescence probes for rapid, sensitive, and label-free detection of Hg2+ and biothiols in complex matrices

In this work, unmodified carbon nanodots are demonstrated as novel and environmentally-friendly fluorescence probes for the sensing of Hg(2+) and biothiols with high sensitivity and selectivity.     

Customizing the Electrochemical Properties of Carbon Nanodots by Using Quinones in Bottom‐Up Synthesis

We show how the redox potentials of carbon nanodots (CNDs) can be modulated by employing quinones as electroactive precursors during a microwave‐assisted synthesis. We prepared and characterized a redox library of CNDs, demonstrating that this approach can promote the use of carbon nanodots for ad hoc applications, including photocatalysis.     

Production of Metal‐Free Composites Composed of Graphite Oxide and Oxidized Carbon Nitride Nanodots and Their Enhanced Photocatalytic Performances

A novel metal‐free composite (GN) composed of two types of carbon‐based nanomaterials, graphite oxide (GO) and 2D oxidized carbon nitride (OCN) nanodots was produced. Chemical and morphological characterizations reveal that GN contains a main component of GO with well‐dispersed 2D OCN nanodots. GN shows enhanced photocatalytic performance for degrading an organic pollutant, Rhodamine B, under visible light.     

A Stress Self-Adaptive Structure to Suppress the Chemo-mechanical Degradation for High Rate and Ultralong Cycle Life Sodium Ion Batteries

Transition-metal phosphides (TMPs) as typical conversion-type anode materials demonstrate extraordinary theoretical charge storage capacity for sodium ion batteries, but the unavoidable volume expansion and irreversible capacity loss upon cycling represent their long-standing limitations. Herein we report a stress self-adaptive structure with ultrafine FeP nanodots embedded in dense carbon microplates skeleton (FeP@CMS) via the spatial confinement of carbon quantum dots (CQDs). Such an architecture delivers a record high specific capacity (778 mAh g⁻¹ at 0.05 A g⁻¹) and ultra-long cycle stability (87.6 % capacity retention after 10 000 cycles at 20 A g⁻¹), which outperform the state-of-the-art literature. We decode the fundamental reasons for this unprecedented performance, that such an architecture allows the spontaneous stress transfer from FeP nanodots to the surrounding carbon matrix, thus overcomes the intrinsic chemo-mechanical degradation of metal phosphides.     

Facile preparation of holmium(Ⅲ)-doped carbon nanodots for fluorescence/magnetic resonance dual-modal bioimaging

In this work, we report the synthesis of holmium(III)-doped carbon nanodots(Ho BCDs) as fluorescence/magnetic resonance(FL/MR) dual-modal imaging probes via a facile hydrothermal process using citrate acid(CA), branched-polyethylenimine(BPEI) and diethylenetriamine pentaacetic acid hydrate holmium(III) dihydrogen salt(Ho-DTPA) as carbon source, passivating reagent and holmium source, respectively.The thus prepared Ho BCDs exhibited ultra-small particle size(~4 nm), high water solubility and bright fluorescence with an absolute quantum yield of 8%. Additionally, grey-scaled T_1-weighted images of Ho BCDs solution appeared to be apparently brighter than that of deionized water and un-doped blue carbon nanodots(BCDs) solution. In addition, in vitro toxicity assay validated superior biocompatibility of Ho BCDs. Using He La cells as models, Ho BCDs-treated cells were observed to emit blue fluorescence located both in plasma and nucleus, and presented positive contrast enhancement in T_1-weighted images, suggesting their potentials for practical biomedical applications.