Carbon nanodots: synthesis, properties and applications

Li, Haitao; Kang, Zhenhui; Liu, Yang; Lee, Shuit‐Tong

doi:10.1039/c2jm34690g

Cited by 2,379 publications

(1,641 citation statements)

References 176 publications

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“…Compared with conventional CQDs, GQDs are generally smaller and of higher crystallinity. [22] And GQDs have larger specific surface areas and more accessible edges, which results in an influence of capacitance. In our case, HRTEM images of the GQDs/MnO 2 -3 show that many dots are uniformly distributed in the field of vision, as shown in Figure S3a (Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

“…This weak 2D band without a typical graphite shoulder shows low I 2D /I G ratio (0.5) implying the few-layered feature of GQDs in GQDs/MnO 2 , [25] which further prove the formation of GQDs. [22] The detailed discussion is shown in Figure S3 (Supporting Information). The peak intensity ratio between the disorder-induced D peak and sp 2 planes of GQDs are decreased after prolonging the deposition time of PECVD, which is mainly attributed to the edges of GQDs with a low stability that are etched away through growth of GQDs and finally become regular and straighter.…”

Section: Resultsmentioning

confidence: 99%

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Heterostructural Graphene Quantum Dot/MnO₂ Nanosheets toward High‐Potential Window Electrodes for High‐Performance Supercapacitors

et al. 2018

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a great deal of research effort has been devoted on high energy density supercapacitors. According to the equation of energy density E = 1/2 CV 2 , the energy density (E) of supercapacitors can be enhanced by increasing either voltage window (V) or specific capacitance (C). [5] For high specific capacitance, one of the research efforts should concentrate on using transition metal oxides (TMO) (e.g., MnO 2 , RuO 2 ) as electrode materials. [6,7] They can provide great specific capacitance due to the pseudocapacitive characteristic. [8,9] Among TMO materials, MnO 2 is one of the most potential materials for supercapacitors due to its high theoretical specific capacitance, environmental friendliness, and the high practical voltage window (about 1 V). [2] However, it has suffered from intrinsically low conductivity and specific surface area, which severely restrict its further development in practical application of supercapacitors. In this regard, integrating nanostructured MnO 2 and conductive carbon materials to fabricate novel hybrid nanostructures is a plausible solution to overcome this obstacle. [4] Further, some research efforts have been accordingly performed to synthesize hybrid nanostructures electroactive materials for constructing supercapacitors with considerable performance. Some researchers accordingly synthesized highperformance nanostructured MnO 2 -carbon materials electrodes, whose specific capacitance is close to theoretical value. However, the undesirable contact resistances that produced by the weak and noncoherent TMO/conductor interfaces lead to sluggish kinetics for charge transport, which requires further improvement. [10,11] In order to further improve the energy density, some researchers have concentrated on enlarging the voltage window of supercapacitors. The applications of aqueous electrolytes have been limited by their theoretical voltage window (≈1.23 V) and the practical voltage window is mostly lower than about 1 V for supercapacitors. [12] To extend the voltage window, various techniques have been applied, such as dual shuttle-ion electrolytes, [13,14] pH adjustment of electrolytes, [15] and concentrated electrolytes. [16][17][18] All of these methods have complex processing technologies and sacrifice capacitance, so being difficult for practical applications. Recently, Zhu and co-workers

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Heterostructural Graphene Quantum Dot/MnO₂ Nanosheets toward High‐Potential Window Electrodes for High‐Performance Supercapacitors

et al. 2018

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“…[1][2][3][4][5][6][7][8] Especially, CDs, owing to their superior performance in terms of water solubility, stability, toxicity, resistance to photobleaching, and biocompatibility, have recently drawn significant attention. [9][10][11][12][13][14][15] The electron injection from CDs to TiO 2 was demonstrated to be feasible and the CD-sensitized TiO 2 photoelectrodes have been applied in photocatalysis and PVs. 10,[16][17][18][19][20][21] However, it is still a challenge to achieve efficient electron injection from CDs to TiO 2 under sunlight, 21 which is a primary photophysical process in generating photocurrent in CD-based PVs.…”

Section: Introductionmentioning

confidence: 99%

“…[9][10][11][12][13][14][15] The electron injection from CDs to TiO 2 was demonstrated to be feasible and the CD-sensitized TiO 2 photoelectrodes have been applied in photocatalysis and PVs. 10,[16][17][18][19][20][21] However, it is still a challenge to achieve efficient electron injection from CDs to TiO 2 under sunlight, 21 which is a primary photophysical process in generating photocurrent in CD-based PVs. 22,23 To date, the power conversion efficiency of CD-based PVs has been only 0.13%, as reported by Mirtchev and co-workers.…”

Section: Introductionmentioning

confidence: 99%

“…24,25 The surface defects are unstable and dissipative in energy, which are unfavorable for efficient electron injection in PVs. 23,[26][27][28] In addition, the reported CDs are generally passivated with insulating long chain molecules, 10,12,29 which act as tunneling barriers and are against efficient electron injection and well performing CD-based optoelectronic devices. 22,30 To realize efficient CD-sensitized TiO 2 PVs under sunlight, the CDs should exhibit intrinsic absorption in the visible region and be integrated effectively with TiO 2 .…”

Section: Introductionmentioning

confidence: 99%

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Towards efficient photoinduced charge separation in carbon nanodots and TiO₂ composites in the visible region

Sun

et al. 2015

Phys. Chem. Chem. Phys.

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Towards efficient photoinduced charge separation in carbon nanodots and TiO2 composites in the visible region Sun, M.; Qu, S.; Ji, W.; Jing, P.; Li, D.; Qin, L.; Cao, J.; Zhang, H.; Zhao, J.; Shen, D. General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. In this work, photoinduced charge separation behaviors in non-long-chain-molecule-functionalized carbon nanodots (CDs) with visible intrinsic absorption (CDs-V) and TiO 2 composites were investigated. Efficient photoinduced electron injection from CDs-V to TiO 2 with a rate of 8.8 Â 10 8 s À1 and efficiency of 91% was achieved in the CDs-V/TiO 2 composites. The CDs-V/TiO 2 composites exhibited excellent photocatalytic activity under visible light irradiation, superior to pure TiO 2 and the CDs with the main absorption band in the ultraviolet region and TiO 2 composites, which indicated that visible photoinduced electrons and holes in such CDs-V/TiO 2 composites could be effectively separated. The incident photon-to-current conversion efficiency (IPCE) results for the CD-sensitized TiO 2 solar cells also agreed with efficient photoinduced charge separation between CDs-V and the TiO 2 electrode in the visible range. These results demonstrate that non-long-chainmolecule-functionlized CDs with a visible intrinsic absorption band could be appropriate candidates for photosensitizers and offer a new possibility for the development of a well performing CD-based photovoltaic system.

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Bio‐Based Hyperbranched Polyurethane Nanocomposites

Karak

2015

Encyclopedia of Polymer Science and Technology

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BIO-BASED HYPERBRANCHED POLYURETHANE NANOCOMPOSITESadjusting the ratio of isocyanate (-NCO) to hydroxyl (-OH) functionality and the chemical composition in the final structure of the polyurethane, different types of polymeric products like thermosetting resin and elastomer as well as thermoplastic and fiber can be obtained (3). In all such polyurethanes, the main linkage, urethane (-NH-C(=O) -O-) is a unique combination of rigid amide (-NH-C=O), which has a tendency to donate proton, and a flexible ester (-O-C=O) group, which has a tendency to accept proton. Further flexibility arises from the flexible soft segment and long hydrocarbon part of fatty acid chains of the vegetable oil component present in the bio-based segmented polyurethanes. Moreover, they are biodegradable and biocompatible. All these unique features of bio-based polyurethanes widen their applications in the domains of coating, paint, adhesive, sealant, composite, biomaterial, smart material, and so on.Again, incorporation of branching in the polymer structure greatly influences the processing and properties of the branched polymer. Thus hyperbranched polymers are treated as macromolecules for 21st century. These hyperbranched polymers are one type of dendritic polymers ( Fig. 1), where the other type is a perfectly regular structure with a three-dimensional architecture, known as a dendrimer (4). However, hyperbranched polymers are preferred in most of the industrial applications over multistep laborious synthesized dendrimers because of easier and simpler one-step synthetic protocol of the former as they can accommodate some defects in their structures. Thus mass-scale industrial production at relatively low cost is possible for hyperbranched polymers like conventional linear polymers. However, hyperbranched polymers enjoy many advantages over linear polymers (Fig. 1). These include a unique three-dimensional structural architecture with dendritic, linear, and terminal units, the presence of a large number of freely exposed surface groups, low polydispersity index, low viscosity, high solubility, high compatibility with other materials, etc. Therefore, bio-based hyperbranched polyurethanes are preferred as superior materials over their conventional analogs for different advanced applications.However, "virginity is not a virtue" in case of polymer, whatsoever the structural architecture is! Thus bio-based hyperbranched polyurethanes also require to be adulterated by incorporation of appropriate additives or ingredients. It is pertinent to mention here that most of the vegetable oil-based hyperbranched polyurethanes do not have required mechanical strength and toughness, although they possess very good flexibility. In this vein, conventional filled and composite systems are widely used, although both the approaches suffer from serious drawbacks, as a huge amount of additive(s) is necessary to be incorporated to achieve the desired level of performance of the stated polyurethanes. Most importantly, the resultant products lost most of the central a...

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Carbon nanodots: synthesis, properties and applications

Cited by 2,379 publications

References 176 publications

Heterostructural Graphene Quantum Dot/MnO₂ Nanosheets toward High‐Potential Window Electrodes for High‐Performance Supercapacitors

Heterostructural Graphene Quantum Dot/MnO₂ Nanosheets toward High‐Potential Window Electrodes for High‐Performance Supercapacitors

Towards efficient photoinduced charge separation in carbon nanodots and TiO₂ composites in the visible region

Bio‐Based Hyperbranched Polyurethane Nanocomposites

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Carbon nanodots: synthesis, properties and applications

Cited by 2,379 publications

References 176 publications

Heterostructural Graphene Quantum Dot/MnO2 Nanosheets toward High‐Potential Window Electrodes for High‐Performance Supercapacitors

Heterostructural Graphene Quantum Dot/MnO2 Nanosheets toward High‐Potential Window Electrodes for High‐Performance Supercapacitors

Towards efficient photoinduced charge separation in carbon nanodots and TiO2 composites in the visible region

Bio‐Based Hyperbranched Polyurethane Nanocomposites

Contact Info

Product

Resources

About

Heterostructural Graphene Quantum Dot/MnO₂ Nanosheets toward High‐Potential Window Electrodes for High‐Performance Supercapacitors

Heterostructural Graphene Quantum Dot/MnO₂ Nanosheets toward High‐Potential Window Electrodes for High‐Performance Supercapacitors

Towards efficient photoinduced charge separation in carbon nanodots and TiO₂ composites in the visible region