ChemInform Abstract: Carbon Dots: The Newest Member of the Carbon Nanomaterials Family

Abstract Nanotechnology has become one of the most important topics since the beginning of the twenty-first century in numerous fields including drug synthesis and delivery, environmental protection, electronics manufacture, and astronomy due to their nanoscale particles and their properties. The traditional semi-quantum dots are replaced by a new category of fluorescent carbon nanomaterials. Carbon dots (CDs) have been explored in the last few years for their simple synthetic accession, good bio-consonance, and several revelation applications. This review explains the fluorescent properties of CDs in brief, giving also a background on CDs discovery, structure, and composition, as well as on nanocomposites, green synthesis, and their applications. Resources conservation can be achieved by using recycled substances for sustainable development which lead to a new technology. Fluorescent CDs synthesized from food wastes like bananas, orange peel waste, sugarcane bagasse, Trapa bispinosa peels, bread, and jaggery have several applications such as sensing, drug delivery, gene transfer, biological imaging, and food safety. In this study, we concentrate on CDs greener methods to prepare effective and biocompatible CDs.

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Synthetic Approach to Rice Waste-Derived Carbon-Based Nanomaterials and Their Applications

Nanomanufacturing ◽

10.3390/nanomanufacturing1030010 ◽

2021 ◽

Vol 1 (3) ◽

pp. 109-159

Author(s):

Shamroza Mubarik ◽

Nawal Qureshi ◽

Zainab Sattar ◽

Aqeela Shaheen ◽

Ambreen Kalsoom ◽

...

Keyword(s):

Carbon Nanotubes ◽

Carbon Dots ◽

Carbon Nanomaterials ◽

Agricultural Waste ◽

Green Technology ◽

Water Remediation ◽

Synthetic Approach ◽

Biomass Waste ◽

Carbon Based Nanomaterials ◽

Carbon Based

The utilization of biomass waste to produce valuable products has extraordinary advantages as far as both the economy and climate are concerned, which have become particularly significant lately. The large-scale manufacturing of agricultural waste, mainly rice by-products (rice husk, rice straw, and rice bran), empowers them to be the most broadly examined biomasses as they contain lignin, cellulose, and hemicellulose. Rice waste was first used to incorporate bulk materials, while the manufacturing of versatile nanostructures from rice waste at low cost has been developed in recent years and attracts much consideration nowadays. Carbon-based nanomaterials including graphene, carbon nanotubes, carbon dots, fullerenes, and carbon nanofibers have tremendous potential in climate and energy-related applications. Various methods have been reported to synthesize high-value carbon nanomaterials, but the use of green technology for the synthesis of carbon nanomaterials is most common nowadays because of the abundant availability of the starting precursor, non-toxicity, low fabrication cost, ease of modification, and eco-friendly nature; therefore, reusing low-value biomass waste for the processing of renewable materials to fabricate high-value products is remarkable. Carbon nanomaterials derived from rice waste have broad applications in various disciplines owing to their distinctive physicochemical, electrical, optical, mechanical, thermal, and enhanced biocompatibility properties. The main objective of this review and basic criteria of selecting examples and explanations is to highlight the green routes for the synthesis of carbon nanomaterials—i.e., graphene, carbon nanotubes, and carbon dots—from rice biomass waste, and their extensive applications in biomedical research (bio-imaging), environmental (water remediation), and energy-related (electrodes for supercapacitors, Li-ion battery, fuel cells, and solar cells) applications. This review summarizes recent advancements, challenges, and trends for rice waste obtained from renewable resources for utilization in the fabrication of versatile carbon-based nanomaterials.

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Finding Value in Wastewaters from the Cork Industry: Carbon Dots Synthesis and Fluorescence for Hemeprotein Detection

Molecules ◽

10.3390/molecules25102320 ◽

2020 ◽

Vol 25 (10) ◽

pp. 2320

Author(s):

Marta R. Alexandre ◽

Alexandra I. Costa ◽

Mário N. Berberan-Santos ◽

José V. Prata

Keyword(s):

Cytochrome C ◽

Carbon Dots ◽

Carbon Nanomaterials ◽

Direct Detection ◽

Photophysical Properties ◽

Industrial Effluent ◽

Protein Detection ◽

Fluorescence Probes ◽

Collisional Quenching ◽

Cork Industry

Valorisation of industrial low-value waste residues was preconized. Hence, carbon dots (C-dots) were synthesized from wastewaters of the cork industry—an abundant and affordable, but environmentally-problematic industrial effluent. The carbon nanomaterials were structurally and morphologically characterised, and their photophysical properties were analysed by an ensemble of spectroscopy techniques. Afterwards, they were successfully applied as highly-sensitive fluorescence probes for the direct detection of haemproteins. Haemoglobin, cytochrome c and myoglobin were selected as specific targets owing to their relevant roles in living organisms, wherein their deficiencies or surpluses are associated with several medical conditions. For all of them, remarkable responses were achieved, allowing their detection at nanomolar levels. Steady-state and time-resolved fluorescence, ground-state UV–Vis absorption and electronic circular dichroism techniques were used to investigate the probable mechanisms behind the fluorescence turn-off of C-dots. Extensive experimental evidence points to a static quenching mechanism. Likewise, resonance energy transfer and collisional quenching have been discarded as excited-state deactivating mechanisms. It was additionally found that an oxidative, photoinduced electron transfer occurs for cytochrome c, the most electron-deficient protein. Besides, C-dots prepared from citric acid/ethylenediamine were comparatively assayed for protein detection and the differences between the two types of nanomaterials highlighted.

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Carbon Nanotubes, Graphene, and Carbon Dots as Electrochemical Biosensing Composites

Molecules ◽

10.3390/molecules26216674 ◽

2021 ◽

Vol 26 (21) ◽

pp. 6674

Author(s):

Raja Ram Pandey ◽

Charles C. Chusuei

Keyword(s):

Mechanical Properties ◽

Carbon Nanotubes ◽

Carbon Dots ◽

Carbon Nanomaterials ◽

Electrochemical Sensing ◽

Design Elements ◽

Electrochemical Biosensing ◽

Active Nanoparticles ◽

Carry Over

Carbon nanomaterials (CNMs) have been extensively used as electrochemical sensing composites due to their interesting chemical, electronic, and mechanical properties giving rise to increased performance. Due to these materials’ unknown long-term ecological fate, care must be given to make their use tractable. In this review, the design and use of carbon nanotubes (CNTs), graphene, and carbon dots (CDs) as electrochemical sensing electrocatalysts applied to the working electrode surface are surveyed for various biosensing applications. Graphene and CDs are readily biodegradable as compared to CNTs. Design elements for CNTs that carry over to graphene and CDs include Coulombic attraction of components and using O or N atoms that serve as tethering points for attaching electrocatalytically active nanoparticles (NPs) and/or other additives.

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Coffee Grounds-Derived CNPs for Efficient Cr(VI) Water Remediation

Nanomaterials ◽

10.3390/nano11051064 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1064

Author(s):

Simona Bettini ◽

Michela Ottolini ◽

Rosanna Pagano ◽

Sudipto Pal ◽

Antonio Licciulli ◽

...

Keyword(s):

Carbon Dots ◽

Carbon Nanoparticles ◽

Carbon Nanomaterials ◽

Aqueous Media ◽

Weak Acid ◽

Water Remediation ◽

Atomic Force ◽

Coffee Grounds ◽

Wide Range ◽

Chemical Groups

Carbon nanomaterials are a group of materials characterized by sp2/sp3 carbon backbone which, combined with surface atoms and/or chemical groups, ensures peculiar physical chemical features for a wide range of applications. Among these materials, carbon dots and carbon nanoparticles belong to carbon nanomaterials with a few nanometer dimensions. In this work, carbon nanoparticles were produced from spent coffee grounds as sustainable carbon source through a simple, cheap and eco-friendly procedure according to an oxidation process (at controlled temperature) driven by hydrogen peroxide. Atomic Force Microscope (AFM) and fluorescence, UV-Vis absorption, FT-IR and Raman spectroscopy were used to assess the formation of carbon nanomaterials of about 10 nm with the typical emission and absorption properties of carbon dots and peculiar surface features. In fact, the presence of heteroatoms, i.e., phosphorus, and the carbonyl/carboxyl surface groups on carbon nanoparticles, was proposed to confer peculiar properties allowing the fast Mn(VII) reduction to Mn(II) at neutral pH and the Cr(VI) reduction to Cr(III) in weak acid aqueous media.

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Precursor-Dependent Photocatalytic Activity of Carbon Dots

Molecules ◽

10.3390/molecules25010101 ◽

2019 ◽

Vol 25 (1) ◽

pp. 101 ◽

Cited By ~ 4

Author(s):

Amadio Emanuele ◽

Simone Cailotto ◽

Carlotta Campalani ◽

Lorenzo Branzi ◽

Carlotta Raviola ◽

...

Keyword(s):

Citric Acid ◽

Carbon Dots ◽

Methyl Viologen ◽

Photocatalytic Performance ◽

Carbon Nanomaterials ◽

Supramolecular Assembly ◽

Structural Features ◽

Structural And Optical Properties ◽

Structure Activity ◽

Activity Dependence

This work systematically compares both structural features and photocatalytic performance of a series of graphitic and amorphous carbon dots (CDs) prepared in a bottom-up manner from fructose, glucose, and citric acid. We demonstrate that the carbon source and synthetic procedures diversely affect the structural and optical properties of the CDs, which in turn unpredictably influence their photo electron transfer ability. The latter was evaluated by studying the photo-reduction of methyl viologen. Overall, citric acid-CDs were found to provide the best photocatalytic performance followed by fructose- and glucose-CDs. However, while the graphitization of glucose- and citric acid-CDs favored the photo-reaction, a reverse structure–activity dependence was observed for fructose-CDs due to the formation of a large graphitic-like supramolecular assembly. This study highlights the complexity to design in advance photo-active bio-based carbon nanomaterials.

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A General Method Towards Efficient Synthesis and Fluorescence Tuning of Carbon Black-Derived Carbon Dots via Controlled Liquid Oxidization

Australian Journal of Chemistry ◽

10.1071/ch15014 ◽

2015 ◽

Vol 68 (9) ◽

pp. 1446 ◽

Cited By ~ 1

Author(s):

Haoran Yuan ◽

Denian Li ◽

Yan Liu ◽

Chuanxi Xiong

Keyword(s):

Carbon Black ◽

Carbon Dots ◽

Carbon Nanomaterials ◽

Low Cost ◽

Efficient Synthesis ◽

Rapid Preparation ◽

Reduced Pressure ◽

Industrial Carbon ◽

Alkaline Environments ◽

Tuning Strategy

Efficient synthesis and controlled modification of carbon dots (CDs) with tuneable properties on the basis of facile technical routes are of great significance for user-defined applications as well as more insightful understanding of the unique fluorescence from carbon nanomaterials. In this work, we report an improved nitric acid oxidization method towards low-cost and rapid preparation of fluorescent CDs. This is achieved by using industrial carbon black specimens as the precursor and implementing a reduced pressure distillation for the purpose of eliminating excessive acids. Unexpectedly, the product exhibits an interesting dual luminescence behaviour with tuneable characteristics that differs from all previously reported CDs. The strongest emissions at fixed or varied excitations can be simultaneously tuned from blue to green or yellow by simply prolonging the time of acid oxidization. These emissions show distinct stabilities in acid and alkaline environments, thereby making the resultant CDs very promising candidates for pH probes. It is further revealed that this simple synthesis and fluorescence tuning strategy is also applicable to CDs from other carbon blacks.

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Recent Developments in Synthesis and Photocatalytic Applications of Carbon Dots

Catalysts ◽

10.3390/catal10030320 ◽

2020 ◽

Vol 10 (3) ◽

pp. 320 ◽

Cited By ~ 4

Author(s):

Chularat Sakdaronnarong ◽

Amornrat Sangjan ◽

Suthida Boonsith ◽

Dong Chung Kim ◽

Hyeon Suk Shin

Keyword(s):

Carbon Dots ◽

Carbon Nanomaterials ◽

Chemical Degradation ◽

Photocatalytic Properties ◽

Metal Chalcogenides ◽

Chemical Surface ◽

Element Doping ◽

Recent Developments ◽

Transition Metal Chalcogenides ◽

Photocatalytic Applications

The tunable photoluminescent and photocatalytic properties of carbon dots (CDs) via chemical surface modification have drawn increased attention to this emerging class of carbon nanomaterials. Herein, we summarize the advances in CD synthesis and modification, with a focus on surface functionalization, element doping, passivation, and nanocomposite formation with metal oxides, transition metal chalcogenides, or graphitic carbon nitrides. The effects of CD size and functionalization on photocatalytic properties are discussed, along with the photocatalytic applications of CDs in energy conversion, water splitting, hydrogen evolution, water treatment, and chemical degradation. In particular, the enzyme-mimetic and photodynamic applications of CDs for bio-related uses are thoroughly reviewed.

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