Search query: carbon quantum dot   literture review

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abstract: Abstract Semiconductor photocatalyst mediated advanced oxidation processes are regarded as one of the most efficient technologies to mitigate organic pollutants in water. However, poor activity under visible light and the recombination of photogenerated electron and hole pairs hinder large scale applicability of semiconductor photocatalysts for water purification. The modification of semiconductor photocatalysts with carbon quantum dots (CQDs) is of high importance due to low toxicity, aqueous stability, enhanced surface area, economic feasibility, good biocompatibility and chemical inertness of CQDs. In this review, we highlight strategies to improve the activity of conventional semiconductor photocatalysts via coupling with CQDs. The enhanced photocatalytic activity of CQD modified narrow and wide band gap photocatalysts is due mainly to up conversion photoluminescence (UPCL) and the electron reservoir properties of CQDs, while in the case of Z scheme photocatalysts CQDs act as an electron mediator. Finally, a conclusive outlook and suggested research directions are provided to address challenges such as the inadequate separation of photoinduced charge carriers.
author_names: Sheetal Sharma

Vishal Dutta

Pardeep Singh

Pankaj Raizada

Abolfazl Rahmani-Sani

Ahmad Hosseini-Bandegharaei

Vijay Kumar Thakur
title: Carbon quantum dot supported semiconductor photocatalysts for efficient degradation of organic pollutants in water: A review
venue: Journal of Cleaner Production
year: 2019

abstract: Abstract A diverse range of materials (e.g. metallic nanoparticles, semiconductor oxides, composites, polymers, and MOFs) have been reported for sensing applications in water samples based on several transduction techniques (e.g. absorbance, fluorescence, Raman, colorimetry, voltammetry, and plasmon resonance) Recently, carbon quantum dots (CQDs) have gained significant interest as fluorescent and small carbonaceous nanostructures for designing sensing devices (either as produced or through modification) for heavy metals due to their excellent properties (e.g. photostability, facile surface modification, optical tunability, and environmental friendliness) This review provides a comprehensive overview on the role of CQDs as sensors for heavy metals in water. This work will help open up opportunities for the use of CQDs under the diverse field conditions.
author_names: Pooja Devi

Prachi Rajput

Anupma Thakur

Ki-Hyun Kim

Praveen Kumar
title: Recent advances in carbon quantum dot based sensing of heavy metals in water
venue: TrAC Trends in Analytical Chemistry
year: 2019

abstract: CQDs are a new class of carbon material with ultrafine sizes and readily tunable optical properties, which make them extremely intriguing. CQDs have gained widespread attention due to their potential and versatility, and they can be applied in many different fields. One of their many applications is photocatalysis, which has garnered incessant research interest in recent years. State of the art technology utilizes sustainable solar energy, which is both clean and virtually inexhaustible. To date, the photocatalytic performance of CQDs in their raw form is still far from ideal. Nevertheless, they can be substantially enhanced through several modification techniques. In this review, strategies to improve the photocatalytic performance of CQDs, such as size tuning, surface passivation and functionalization, and elemental doping, are extensively discussed. The review also covers the latest advances in the use of CQDs in photocatalysis to address both environmental and energy related issues. Particular emphasis is placed on the formation of 0D/2D heterojunction nanocomposites with several 2D materials, such as graphene, graphitic carbon nitride, metal oxides and metallates, metal oxyhalides, transition metal oxides and chalcogenides. The hybridization routes to binary nanocomposites, and their photocatalytic application to carbon dioxide reduction, hydrogen production, and dye and pollutant degradation, are thoroughly reviewed in this paper.
author_names: Sue Jiun Phang

Lling-Lling Tan
title: Recent advances in carbon quantum dot (CQD) based two dimensional materials for photocatalytic applications
year: 2019

abstract: Abstract This endeavor presents state of the art overview on polymer/carbon based quantum dot nanocomposite. Carbon based quantum dot (graphene quantum dot, carbon nanodot, and polymer dot) are ~10nm. Carbon based quantum dot own exciting features such as tunable optoelectronic and photoluminescence properties, high stability, chemical inertness, low cytotoxicity, and biocompatibility owing to quantum confinement and edge effects. Main emphasis of article was to see the combined effect of polymer and carbon based quantum dot in nanocomposite. Five major categories have been reviewed in this article including conjugated polymer/carbon based quantum dot nanocomposite, epoxy/carbon based quantum dot nanocomposite, polystyrene/carbon based quantum dot nanocomposite, poly(dimethyl siloxane)/carbon based quantum dot nanocomposite, and block copolymer/carbon based quantum dot nanocomposite. The review also refers to cutting edge application areas of polymer/carbon based quantum dot nanocomposite. Conducting polymer/carbon quantum dot nanocomposite has been integrated in energy storage devices, detectors, and electronic devices. These materials are also promising candidates for bulk heterojunction solar cells and light emitting diodes. Another important use is the identification and removal of toxic metals. Functional materials have also been used for fluorescence imaging of live cells. Modification of carbon based quantum dot and incorporation in appropriate polymer matrices can be adopted as powerful future tool enabling desired tailored applicability of nanocomposite in advance high performance technical applications.
author_names: Ayesha Kausar
title: Polymer/carbon based quantum dot nanocomposite: forthcoming materials for technical application
venue: Journal of Macromolecular Science, Part A
year: 2019

abstract: Abstract Zero dimensional (0D) carbon nanomaterials such as carbon (CQDs) and graphene quantum dots (GQDs) have been attracting attention due to their outstanding properties of biocompatibility, nontoxicity, chemical inertness, tunable photoluminescence, low cost and facile surface functionalization. Their potential applications range from biomedical, drug delivery, environmental, photocatalytic to energy storage sectors. Among these, investigations have largely focused on their behavior in environmental sensing, biosensing, and optoelectronics, yet energy storage and conversion systems are progressing rapidly as new promising methods are emerging to solve some of the outstanding challenges with energy at low cost and environmental footprint. By virtue of their rapid electron transfer and high surface area, CQD/GQDs are desirable in these electrochemical applications. Further, functional groups with rich heteroatoms (oxygen, nitrogen, sulfur, phosphorus, boron) on 0D carbon nanomaterials offer desirable active sites for enhanced electrochemical properties. Our review presents recent advances in the fabrication of CQD/GQD based composites for electrochemical systems, their mechanism of action, applications in energy storage (electrochemical capacitors, lithium/sodium ion batteries) and electrocatalysis (oxygen reduction reaction, oxygen/hydrogen evolution reactions, CO2 electroreduction, biofuel cells and electrochemical biosensors) with an analysis of their potential prospects.
author_names: Van Chinh Hoang

Khyati Dave

Vincent G Gomes
title: Carbon quantum dot based composites for energy storage and electrocatalysis: Mechanism, applications and future prospects
year: 2019

abstract: Small carbon nanoparticles are an emerging member of the carbonaceous nanomaterial family and have been subsequently named as "carbon quantum dots" or "carbon nanodots" Generally, carbon quantum dots are a type of spherical or sphere like nanoparticles of less than 10 nm in size. Due to their unique properties, for example, size dependent fluorescence, non toxicity, biocompatibility, and easy accessibility, carbon quantum dots possess a great many potential applications in a range of fields from chemical sensing and imaging to catalysis and drug delivery, and thus are appealing to a number of researchers in nanoscience and nanotechnology. In this review, we give a brief introduction of the synthesis and fundamental properties of carbon quantum dots, then present their applications in metal ion sensing in detail along with illustrating the related mechanisms, and finally come up with some challenges currently faced and future outlooks for this fascinating carbon material. We hope this review could be helpful for readers who are preparing to join and/or have joined the research field of carbon quantum dots.
author_names: Xiao-hui Gao

Cheng Du

Zhihua Zhuang

Wei Chen
title: Carbon quantum dot based nanoprobes for metal ion detection
year: 2016

abstract: Graphene and carbon quantum dots have extraordinary optical and electrical features because of their quantum confinement properties. This makes them attractive materials for applications in photovoltaic devices (PV) Their versatility has led to their being used as light harvesting materials or selective contacts, either for holes or electrons, in silicon quantum dot, polymer or dye sensitized solar cells. In this review, we summarize the most common uses of both types of semiconducting materials and highlight the significant advances made in recent years due to the influence that synthetic materials have on final performance.
author_names: Sofia Paulo

Emilio Jose Palomares

Eugenia Martinez-Ferrero
title: Graphene and Carbon Quantum Dot Based Materials in Photovoltaic Devices: From Synthesis to Applications
venue: Nanomaterials
year: 2016

abstract: Carbon quantum dots (CQDs) are a member of carbon nanostructures family which have received increasing attention for their photoluminescence (PL) physical and chemical stability and low toxicity. The classical semiconductor quantum dots (QDs) are semiconductor particles that are able to emit fluorescence by excitation. The CQDs is mainly referred to photoluminescent carbon nanoparticles less than 10 nm, with surface modification or functionalization. Contrary to other carbon nanostructures, CQDs can be synthesized and functionalized fast and easily. The fluorescence origin of the CQDs is a controversial issue which depends on carbon source, experimental conditions, and functional groups. However, PL emissions originated from conjugated p domains and surface defects have been proposed for the PL emission mechanisms of the CQDs. These nanostructures have been used as nontoxic alternatives to the classical heavy metals containing semiconductor QDs in some applications such as in vivo and in vitro bio imaging, drug delivery, photosensors, chemiluminescence (CL) and etc. This paper will introduce CQDs, their structure, and PL characteristics. Recent advances of the application of CQDs in biotechnology, sensors, and CL is comprehensively discussed.
author_names: Mohammad Jafar Molaei
title: A review on nanostructured carbon quantum dots and their applications in biotechnology, sensors, and chemiluminescence.
venue: Talanta
year: 2019

abstract: In recent years, nano carbon quantum dots (CQDs) have received increasing attention due to their properties such as small size, fluorescence emission, chemical stability, water solubility, easy synthesis, and the possibility of functionalization. CQDs are fluorescent 0D carbon nanostructures with sizes below 10 nm. The fluorescence in CQDs originates from two sources, the fluorescence emission from bandgap transitions of conjugated p domains and fluorescence from surface defects. The CQDs can emit fluorescence in the near infrared (NIR) spectral region which makes them appropriate for biomedical applications. The fluorescence in these structures can be tuned with respect to the excitation wavelength. The CQDs have found applications in different areas such as biomedicine, photocatalysis, photosensors, solar energy conversion, light emitting diodes (LEDs) etc. The biomedical applications of CQDs include bioimaging, drug delivery, gene delivery, and cancer therapy. The fluorescent CQDs have low toxicity and other exceptional physicochemical properties in comparison to heavy metals semiconductor quantum dots (QDs) which make them superior candidates for biomedical applications. In this review, the synthesis routes and optical properties of the CQDs are clarified and recent advances in CQDs biomedical applications in bioimaging (in vivo and in vitro) drug delivery, cancer therapy, their potential to pass blood brain barrier (BBB) and gene delivery are discussed.
author_names: Mohammad Jafar Molaei
title: Carbon quantum dots and their biomedical and therapeutic applications: a review
year: 2019

abstract: Carbon dots (CDs) a class of carbon based sub ten nanometer nanoparticles, have attracted great attention since their discovery fifteen years ago. Because of the outstanding photoluminescence properties, photostability, low toxicity, and low cost, CDs have potential to replace traditional semiconductor quantum dots which have serious drawbacks of toxicity and high cost. This review covers the common top down and bottom up methods for the synthesis of CDs, different categories of CD precursors (small molecules, natural polymers, and synthetic polymers) one pot and multi step methods to produce CDs/photocatalyst composites, and recent advances of CDs on photocatalysis applications mostly in pollutant degradation and energy areas. A broad range of precursors forming fluorescent CDs are discussed, including small molecule sole or dual precursors, natural polymers such as pure polysaccharides and proteins and crude bio resources from plants or animals, and various synthetic polymer precursors with positive, negative, neutral and hydrophilic, hydrophobic, or zwitterionic feature. Because of the wide light absorbance, excellent photoluminescence properties and electron transfer ability, CDs have emerged as a new type of photocatalyst. Recent work of CDs as sole photocatalyst or in combination with other materials (e.g. metal, metal sulfide, metal oxide, bismuth based semiconductor, or other traditional photocatalysts) to form composite catalyst for various photocatalytic applications are reviewed. Possible future directions are proposed at the end of the article on mechanistic studies, production of CDs with better controlled properties, expansion of polymer precursor pool, and systematic studies of CDs for photocatalysis applications.
author_names: Kuan-Wu Chu

Sher Ling Lee

Chi-Jung Chang

Lingyun Liu
title: Recent Progress of Carbon Dot Precursors and Photocatalysis Applications
venue: Polymers
year: 2019