Received date: 15/11/2021; Accepted date: 23/11/2021; Published date: 30/11/2021
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CQDs/carbon nanodots are a replacement class of fluorescent carbon nanomaterials with a size range of 2 nm–10 nm. The majority of the published review publications have emphasised the potential for CQDs to be used in bio-imaging and chemical/biological sensing applications (via simple and cost-effective production processes). However, there is a severe shortage of comprehensive research on the newly created CQDs (particularly doped/co-doped) that are used in a variety of applications. As a result, we've gone over the latest developments in doped and co-doped CQDs (using elements/heteroatoms such as boron (B), fluorine (F), nitrogen (N), sulphur (S), and phosphorous (P)) as well as their production process in this study, reaction conditions, and/or Quantum Yield (QY), and their emerging multi-potential applications including electrical/electronics (such as Light Emitting Diode (LED) and solar cells), fluorescent ink for anti- counterfeiting, optical sensors (for detection of metal ions, drugs, and pesticides/fungicides), gene delivery, and temperature probing. C-QDs that have been produced exhibit high colloidal, photo-, and environmental stability (pH) and do not require a surface passivation step to increase fluorescence. The C-QDs have good PL activity and emission that is not reliant on stimulation. To the best of our knowledge, no excitation-independent C-QDs have ever been synthesized using a natural carbon source via the pyrolysis process . The influence of reaction time and temperature on pyrolysis sheds light on C-QD synthesis. In order to give a reasonable explanation for the genesis of the PL mechanism of as-synthesized C-QDs, we applied machine-learning techniques such as PCA, MCR-ALS, and NMF-ARD-SO. ML approaches can handle and analyze massive PL data sets, and they can also identify the appropriate excitation wavelength for PL investigation . To summarize, it are often noted that there are sizable amount of investigations that involve within the effective preparation and optimization of doped and co-doped CQDs. The hydrothermal method is much utilized within the synthesis of those doped and co-doped CQDs as compared to other synthesis methods. Nevertheless, there are more avenues to explore within the preparation and optimization of those doped and co-doped CQDs via different synthesis protocols in near future, when comparing with the preparation methods of normal CQDs (without doping) . Moreover, supported the above discussed research-investigations, a clear observation is that the precursors alongside the sort of synthesis method (including the reaction conditions like response time and/or temperature) and the sort of doping have an excellent impact on the resultant Quantum Yield (QY) of the as-synthesized doped and co-doped CQDs. However, in many research studies, the explanations behind the enhancements within the QY within the doped and co-doped CQDs as compared to the traditional CQDs aren't completely evaluated. Thus, in near-future, it should be possible to obviously understand the inherent photoluminescence phenomenon within the doped and co-doped CQDs . Furthermore, above 85% of the as-synthesized doped and co-doped CQDs has emitted blue fluorescence. Hence, the doped and co-doped CQDs with multi-colour emissive properties are often explored and consequently utilized in several applications in future. Besides the above, it's been confirmed that the doped and co-doped CQDs are often effectively utilized in several applications including electrical/electronics (such as LED and solar cells), fluorescent ink for anti-counterfeiting, optical sensors (for detection of metal ions, drugs, and pesticides/fungicides) including molecular logic gates, gene delivery, and temperature probing. However, the extent of exploitation of those doped and co-doped CQDs during a big variety of applications (including the biological applications) is a smaller amount as compared to the traditional CQDs and to the opposite nanoparticles (e.g., Super Paramagnetic Iron Oxide Nanoparticles (SPIONs)). Supported the above-given studies, it are often concluded that the doped and co-doped CQDs are potential candidates for emerging applications . Furthermore, more than 85% of the doped and co-doped CQDs produced blue fluorescence when they were manufactured. As a result, doped and co-doped CQDs with multi-color emissive capabilities are frequently investigated and, as a result, will be used in a variety of applications in the future. Aside from the aforementioned applications, it's been confirmed that doped and co-doped CQDs are commonly used in electrical/electronics (such as LED and solar cells), fluorescent ink for anti-counterfeiting, optical sensors (for detection of metal ions, drugs, and pesticides/fungicides), molecular logic gates, gene delivery, and temperature probing. However, when compared to regular CQDs and opposite nanoparticles, the extent of exploitation of such doped and co-doped CQDs in a wide range of applications (including biological applications) is much lower.