Carbonaceous Quantum Dots: Synthesis And Applications

Carbonaceous quantum dots (CQDs), relatively small carbon nanoparticles (<10 nm in size), have sparked the attention over the last few decades for their potential as a promising resource in various fields, such as biomedical, solar cells, sensors, water treatment, energy generation storage because of their benign, abundant, low preparation costs, small size, non-hazardous nature, high biocompatibility, high water solubility and effective alteration nature. Numerous applications in optronics, catalysis, and sensing are made possible by the excellent electronic characteristics of CQDs as electron acceptors and donors that cause photocatalytic activity and electrochemical luminosity. This feature series aims to assess the current status of CQDs by discussing the literature in this field and deliberate the basics, applicability and advancements in the field of CQDs in both scientific and technology circles.

New class of nanocarbon materials, such as luminescent carbon quantum dots (CQDs) has gained a great deal of interest in the area of electrocatalysis, solar cells, bioimaging nanomedicine, a chemical sensor and a light-emitting diode. CQDs exhibit good physio-chemical properties, such as photoluminescence, high crystallization and good dispersibility. The rapid electron transfer, small size and superconductivity of CQDs provide the CQDs-based composite offering enhanced catalytic activity and electric conductivity. However, additional active moieties are present on the surface, which might aid in the formation of multi-component electrically activated catalysts. Additionally, the multi-component catalysts' internal interactions promote charge transfer and catalytic efficiency, both of which are essential for electrochemistry. Therefore, keeping in mind the importance of CQDs, they are synthesized on the basis of two approaches: Top-down and Bottom-up. The bulk material is reduced in size by utilizing chemical and physical processes in the top-down approach. On the contrary, in the bottom-up method, the atoms are assembled and converted into CQDs using polymerization and carbonization through a chemical reaction. Hence, in this chapter, we will discuss the synthesis techniques for CQDs, such as hydrothermal/solvothermal method, laser ablation, arc-discharge method, acidic oxidation, thermal/combustion routes, electrochemical method and microwave pyrolysis method.

Carbonaceous quantum dots (CQDs) is defined as a subclass of carbon nanoparticles, which offer a size of around 10 nm, and have unique characteristics and a wide range of applications in diverse fields. CQDs have attained widespread attention due to their excellent abilities in several domains, including sensing, nanomedicine and environmental remediation. The mode of synthesis for CQDs is quite simple and inexpensive via methods such as microwave pyrolysis, arc-discharge, etc. CQDs are entitled to diverse physical, chemical and biological properties. Besides this, CQDs have various functional groups present on their surface that improve the properties, specifically the catalytic performance by a phenomenon called charge transfer. The physical, optical, electrical, and biological features of CQDs are explored in this chapter.

Carbonaceous quantum dots (CQDs), a prominent figure of carbon materials, offer remarkable impetus in a variety of sectors, including biosensors, biomedical imaging, drug delivery, photonics, photovoltaics, and electrocatalysis, due to their distinctive physicochemical, optical, and electrical capabilities. This chapter attempts to show current advances in CQD characterization, with an emphasis on the essential multifarious function of CQDs using various techniques, such as photoluminescence and fluorescence emission spectroscopy. Additionally, with the aim of developing highly efficient and long-term sustainable CQD-based components, we explore the obstacles and potential directions of CQD-based substances in this developing research field. 

Numerous research fields, including chemistry, electronics, and medical sciences, have concentrated on the production and use of novel functional nanomaterials. Carbon, a component of all organic life forms, is essential for the creation of nanomaterials. The modern carbon-based family component known as carbonaceous quantum dots (CQD) was unintentionally discovered in 2004 while single-walled carbon nanotubes were being purified. Additionally, CQDs have exceptional qualities like outstanding photoluminescence and minimal toxic effects. Outstanding in vitro andin vivo biomedical implications of CQDs include drug/gene delivery, biosensor biotherapy, and theragnostic evolution. Also, CQDs can pass through specific body sites of endothelial inflammation (epithelium of the intestinal tract, liver, for example), tumors or penetrate capillaries due to their small size. For the same reason, nanoparticles are more suitable for intravenous administration than microparticles and also prevent particle aggregation and bypass emboli or thrombi formation. This chapter describes the most contemporary applications of CQDs in diverse biomedical fields. We hope it will provide incalculable insights to inspire discoveries on CQD and delineate a road map toward a broader range of bio applications.

Carbonaceous Quantum Dots (CQDs) are gaining the interest of various research groups owing to their significant features, including water stability, biocompatibility, minimal cytotoxicity, chemical inertness and fluorescence which make them a good candidate in solar cells applications such as photocatalysis, solar energy conversion, photovoltaic solar cells, and Photoelectrochemical cells. CQDs are used in photocatalytic reactions because they can be used as electron sinks to stop the coupling of electron void pairs. The high coefficient of absorption and the broad spectrum of absorption improve the photocatalytic activity. In solar cells, the CQDs are used as sensitizers. CQDs are employed in solar energy generation because they are non-toxic and affordable. This chapter discusses the use of CQDs in solar cells.

Carbonaceous quantum dots (QDs), including carbon and graphene quantum dots, have been widely used recently in various sensing fields, such as healthcare sensing, environmental monitoring, and food safety. Owing to their exceptional electronic, fluorescent, photoluminescent, chemiluminescent, and electrochemiluminescent properties, carbonaceous QDs are essential tools for designing an ultra-sensitive sensing platform. In this chapter, we summarized the applications of carbonaceous QDs in the detection of various target analysts, citing heavy metals, toxic compounds, pesticides, and proteins (DNA, aptamer, and RNA). In this regard, the authors described the effects of synthetic methods and surface functionalization on the properties of carbonaceous QDs and the analytical performance of sensors. We believe that understanding these parameters gives us better sensors that could not be obtained by other means. To give the reader a clear vision of the implementation of these zero-dimensional nanomaterials in sensor architectures, a comparative study has been developed. 

Water stress and scarcity are among the primary issue that the world is witnessing in this era, as pollution of freshwater resources are increasing due to various emerging pollutants, such as pharmaceuticals, personal care products, pesticides, and household and industrial chemicals. Efficient treatment of wastewater is an important aspect of fresh water supply, and such water can also be used for different household activities and other purposes. So for wastewater treatment, different eco-friendly as well as economic approaches have been analyzed, and the use of carbon quantum dots (CQDs) for the treatment of wastewater is efficient and effective technique extensively studied in the last few years. CQDs are promising nanomaterials for water pollution treatment due to their small particle sizes, tuneable fluorescent properties and containing oxygen-based functional groups. In this chapter, the chemical and physical attributes of CQDs, raw substances and methodologies being utilized in the synthesis, and stability of CQDs, along with their effective employment in wastewater remediation and treatment, has discussed in detail. 

Carbon quantum dots (CQDs) are a type of carbon nanomaterial that has lately received attention as a potential replacement for standard semiconductor quantum dots (QDs). CQDs feature a quasi-spherical structure and amorphous to nanocrystalline carbon cores with diameters of 10-20 nm. Based on the carbon core, CQDs are further classified as graphene quantum dots (GQDs), carbon nanodots (CNDs), and polymer dots (PDs). CQDs exhibit unique electrical and optical properties due to their bigger edge effects and quantum confinement; better than graphene oxide nanosheets, they can also be easily split into electrons and holes due to their high dielectric constant and extinction coefficient. CQDs are crucial in the sector of energy storage and transformation because CQDs offer the advantageous properties of low toxicity, environmental friendliness, low cost, photostability, favourable charge transfer with increased electronic conductivity, and comparably simple synthesis processes. Due to their superior crystal structure and surface properties, CQD nanocomposites often helped to shorten charge transfer paths and maintain electrode material cycle stability. CQDs provide cost-effective and environmentally friendly nanocomposites used for supplying high energy density and stable electrodes for energy storage applications. This chapter provides a summary of the role that CQDs play in energy transmit technologies, including solar cells, supercapacitors, lithium-ion batteries, and hydrogen and oxygen evolution reactions.

Carbonaceous quantum dots (CQDs) are carbon nanomaterials offering significant contributions in the fields of sensing, biosensing, optoelectronics, and energy storage. CQDs materials with edge defects are suitable candidates for LED emitters, water splitting, optoelectronic and photodetectors devices. The role of attached functional groups and edge effects on flexible energy storage devices is discussed in this chapter. The future prospects and underlying challenges for CQD-based material for wastewater remediation, in addition to factors such as their sustainability, durability, performance and economics in the context of industrial scale-up, have also been explored in this chapter