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In this study, Mesosphaerum suaveolens extracts were used for the green fabrication of fluorescent Carbon Quantum Dots (CQDs) by the microwave-assisted method. This study unravels the effect of CQDs on improving the photocatalytic degradation of methylene blue (MB) and Rhodamine B (RhB) dyes followed by the anticancer activity against human breast cancer cells (MDA-MB-231). The bio-fabricated CQDs indicated various characteristics that were analyzed, including phase, structure, functional groups, and binding energies. The CQDs displayed notable photocatalytic performance in the removal of MB (80.73%) and RhB (92.3%) dye, after 200 min of sunlight irradiation. The highest catalytic degradation activity of the CQDs is accredited to their high electron transport at the edges, which is helpful to the efficient separation of electron–hole pairs. Furthermore, the anticancer activity of CQDs was demonstrated against human breast cancer cells (MDA-MB-231). This research suggests that bio-fabricated CQDs act as active photocatalysts and hold promise as a potentially ideal material for mitigating water pollution and exploring anticancer potentials in the future. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) have gained extensive attention due to their excellent properties and wide applications. In this study, we selected the common Chinese herb mugwort as the carbon source and employed the microwave heating method to synthesize CQDs with a quantum yield of 13.54 %. These CQDs exhibited blue fluorescence under UV light irradiation. Furthermore, we constructed a fluorescence resonance energy transfer (FRET) mechanism by combining CQDs with copper nanoparticles (CuNPs) for the detection of melamine. The detection limit for melamine was determined to be 0.83 nmol/L, with a linear range of 1–100 nmol/L. The results demonstrated the potential of this sensing system for the sensitive and selective detection of melamine. [ABSTRACT FROM AUTHOR]

In the field of antimicrobial nanomaterials, biomass‐derived carbon quantum dots have attracted great attention from contemporary researchers due to their unique physicochemical properties and favorable biosafety. In this study, novel carbon quantum dots (CQDs) were synthesized from tannic acid by a one‐step hydrothermal method. The polymeric CQDs have good surface functionality and hydrophilicity with a large number of hydroxyl, carboxyl and amino functional groups. Antimicrobial experiments showed that CQDs had a good inhibitory effect on Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus, as well as the drug‐resistant bacterium methicillin‐resistant Staphylococcus aureus. Scanning electron microscopy showed that the morphology of S.aureus cells treated with CQDs became shrivelled and irregular, the surface of E.coli cells protruded to form irregular vesicles, and the whole became shriveled up, whereas MRSA cells appeared to be depressed in the middle, and there was a residue of adherent CQDs on the cell surface. In addition, CQDs exhibit selective fluorescence bursting behavior for ferric ions and can be used as fluorescent probes for rapid, sensitive and selective detection of Fe3+. Therefore, CQDs not only possess good bacteriostatic properties, but also serve as fluorescent sensors for the detection of Fe3+. It can be used as a potential sensing array for selective detection of iron ions and bacterial abatement from contaminated water. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs), as a novel category of zero-dimensional fluorescent materials, have garnered significant interest because of their distinctive optical characteristics, low toxicity, and easy surface modification. However, most techniques used to manufacture CQDs involve costly raw materials, intricate production processes, or hazardous chemicals. In this study, innovatively, low-cost, renewable, and green biomass raw material, camphor tree waste leaves, were employed to prepare CQDs through a simple one-step hydrothermal approach under relatively mild conditions. The results indicate that the prepared CQDs had a size of around 1.6 nm and a thickness of one to six layers of graphene. They can function as a reliable fluorescent probe for detecting Fe3+, exhibiting a limit of detection (LOD) of 2.03 μM. The full utilization of renewable resources, combined with relatively simple hydrothermal processing, enables the environmentally friendly and economical production of CQDs that have broad prospects for metal ion sensing applications. [ABSTRACT FROM AUTHOR]

Considering that high-purity fresh water is employed in the green production of hydrogen via commercial water electrolyzers and that over 80% of the global population faces significant water safety risks, it is essential to explore alternative water sources. One such alternative is the use of produced water from oil extraction processes. Hence, the main objective of this study is to evaluate the effect of the oil content of oilfield production water on the production of green hydrogen by electrolysis in the presence of carbon quantum dots (CQDs). For this purpose, various electrochemical techniques, such as linear sweep voltammetry (LSV), cyclic voltammetry (CV), and potentiometry, were used to identify the effect of crude oil during hydrogen production. Thermogravimetric analysis (TGA), mass spectrometry (MS), and Fourier-transform infrared spectroscopy (FTIR) were employed to discern the adsorption of crude oil onto the electrodes, quantify the gas fractions generated during the process and identify the functional groups present after the procedure, respectively. Also, optical microscopy was employed to follow the droplet size in the emulsion. The results show that using CQDs affects the Faradaic efficiency, which increases from 77% to 83% with the incorporation of CQDs. In the presence of CQDs, the effects generated by the presence of the oil are inhibited at low oil concentrations. On the contrary, hydrogen production increases by 10.0% (0.1 mL/min) with a faradaic efficiency of 83% and a half-cell efficiency of 41%, compared to the record obtained with the maximum concentration of emulsified crude oil (400 mg/L). The mean size of the initial emulsion droplets was 3.4 μm. At the end of the test, there was evidence of complete breakage of the emulsion due to the effect of the applied electric field. No evidence of adsorption of crude oil on graphite electrodes during electrolysis is observed based on the tests. It has been shown that green hydrogen production from crude oil production water is feasible due to the proposed disruptive electrolytes in the produced water, which inhibit the effect of oil content in the O/W emulsion. This allows the implementation of a new green energy production initiative aligned with the global goal of achieving net zero emissions (NZE) by 2050. The current investigation presents a prospective alternative for harnessing the 18 kW electrical energy potential employed within emulsion-breaking processes within a Colombian field for treatment of around 1000 bpd. This alternative offers a theoretical potential for hydrogen production, approximating 7.36 kW, thus representing a promising opportunity for practical field deployment. • CQDs in electrolysis enhance green hydrogen production efficiency from oilfield-produced water due to their conductive properties. • CQDs significantly increases Faradaic efficiency, inhibiting crude oil's negative effects on hydrogen generation. • Optimized electrolysis with CQDs result in 10% higher hydrogen production at high concentrations of emulsified crude oil. • CQDs mitigate crude oil's negative effects on the system, such as reduced conductivity and electrode degradation. • Gas analysis demonstrates the feasibility of converting oilfield production water into a valuable resource for green energy. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs), synthesized through controlled microplasma treatment of orange juice, exhibit unique luminescent characteristics. The impact of synthesis time on particle size was investigated. Deconvoluted emission spectra displayed broad bands, peaking at an excitation wavelength of 350 nm for CQD sizes of 2.06, 2.4, and 3.09 nm, indicating multiple fluorescence peaks. This suggests a mixture of CQDs with different excitation energies on their surfaces. Luminescence kinetics unveiled three exponential decay components with time constants of 2.73, 4.61, and 3.27 ns, indicating multiple luminescent centers. Emission behavior affected by excitation wavelengths ranging from 350 to 490 nm suggests that quantum transition probabilities are influenced by impurities or defects. These findings emphasize the size‐dependent optical properties and exciton self‐trapping (EST) emission of CQDs. The calculation of the Huang‐Rhys factor S values underscores the profound influence of carrier‐phonon coupling and the Huang‐Rhys factor on the emergence of ESTs within CQDs. Understanding these interactions is crucial for fully utilizing the capabilities of CQDs in applications spanning optoelectronics, sensors, bioimaging, and various technological fields. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is a neurodegenerative disease that badly impacts patients and their caregivers. AD is characterized by deposition of amyloid beta (Aβ) and phosphorylated tau protein (pTau) in the brain with underlying neuroinflammation. We aimed to develop a neuroprotective paradigm by loading verapamil (VRH) into hyaluronic acid-modified carbon quantum dots (CQDs) and comparing its effectiveness with the free form in an AD-like model in rats induced by lipopolysaccharide (LPS). The experimental rats were divided into seven groups: control, LPS, CQDs, early free VRH (FVRH), late FVRH, early verapamil carbon quantum dots (VCQDs), and late VCQDs. Characterizations of VCQDs, the behavioral performance of the rats, histopathological and immunohistochemical changes, some AD hallmarks, oxidative stress biomarkers, neuro-affecting genes, and DNA fragmentation were determined. VRH was successfully loaded into CQDs, which was confirmed by the measured parameters. VRH showed enhancement in cognitive functions, disruption to the architecture of the brain, decreased Aβ and pTau, increased antioxidant capacity, modifiable expression of genes, and a decline in DNA fragmentation. The loaded therapy was superior to the free drug. Moreover, the early intervention was better than the late, confirming the implication of the detected molecular targets in the development of AD. VRH showed multifaceted mechanisms in combating LPS-induced neurotoxicity through its anti-inflammatory and antioxidant properties, thereby mitigating the hallmarks of AD. Additionally, the synthesized nanosystem approach exhibited superior neuroprotection owing to the advantages offered by CQDs. However, finding new actionable biomarkers and molecular targets is of decisive importance to improve the outcomes for patients with AD. [ABSTRACT FROM AUTHOR]

Upconversion nanoparticles (UCNPs) and carbon quantum dots (CQDs) have emerged as promising candidates for enhancing both the stability and efficiency of perovskite solar cells (PSCs). Their rising prominence is attributed to their dual capabilities: they effectively passivate the surfaces of perovskite-sensitive materials while simultaneously serving as efficient spectrum converters for sunlight. In this work, we synthesized UCNPs doped with erbium ions as down/upconverting ions for ultraviolet (UV) and near-infrared (NIR) light harvesting. Various percentages of the synthesized UCNPs were integrated into the mesoporous layers of PSCs. The best photovoltaic performance was achieved by a PSC device with 30% UCNPs doped in the mesoporous layer, with PCE = 16.22% and a fill factor (FF) of 74%. In addition, the champion PSCs doped with 30% UCNPs were then passivated with carbon quantum dots at different spin coating speeds to improve their photovoltaic performance. When compared to the pristine PSCs, a fabricated PSC device with 30% UCNPs passivated with CQDs at a spin coating speed of 3000 rpm showed improved power conversion efficiency (PCE), from 16.65% to 18.15%; a higher photocurrent, from 20.44 mA/cm2 to 22.25 mA/cm2; and a superior fill factor (FF) of 76%. Furthermore, the PSCs integrated with UCNPs and CQDs showed better stability than the pristine devices. These findings clear the way for the development of effective PSCs for use in renewable energy applications. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rapid discrimination of bacteria is currently an emerging trend in the fields of food safety, medical detection, and environmental observation. Traditional methods often require lengthy culturing processes, specialized analytical equipment, and bacterial recognition receptors. In response to this need, we have developed a paper-based fluorescence sensor array platform for identifying different bacteria. The sensor array is based on three unique carbon quantum dots (CQDs) as sensing units, each modified with a different antibiotic (polymyxin B, ampicillin, and gentamicin). These antibiotic-modified CQDs can aggregate on the bacterial surface, triggering aggregation-induced fluorescence quenching. The sensor array exhibits varying fluorescent responses to different bacterial species. To achieve low-cost and portable detection, CQDs were formulated into fluorescent ink and used with an inkjet printer to manufacture paper-based sensor arrays. A smartphone was used to collect the responses generated by the bacteria and platform. Diverse machine learning algorithms were utilized to discriminate bacterial types. Our findings showcase the platform's remarkable capability to differentiate among five bacterial strains, within a detection range spanning from 1.0 × 103 CFU/mL to 1.0 × 107 CFU/mL. Its practicality is further validated through the accurate identification of blind bacterial samples. With its cost-effectiveness, ease of fabrication, and high degree of integration, this platform holds significant promise for on-site detection of diverse bacteria. [ABSTRACT FROM AUTHOR]

In this study, the combination of octahedral Zn 2 SnO 4 with the carbon quantum dots (CQDs) is pioneered for the efficient detection of triethylamine. CQDs-modified Zn 2 SnO 4 materials were synthesized to perform rapid detection of trace triethylamine present in air. In the gas test, the optimal composite's response value to triethylamine is 600% higher than the value of the original Zn 2 SnO 4 to triethylamine, and the tendency of selective to triethylamine is more than ten times than other kinds of gases and possesses a short response/recovery times of 18 s/29 s. The exceptional properties of the composite are attributed to the superb electron transport capacity brought by the modification of 5 nm carbon quantum dots. The novel material will solve the issues of slow reaction time and low response of previous materials in detecting triethylamine. [ABSTRACT FROM AUTHOR]

The carbon‐based nanostructures have led to the development of theranostic nanoplatforms for simultaneous diagnosis and therapy due to their effective cell membrane‐penetration ability, low degree of cytotoxicity, excellent pore volume, substantial chemical stability, and reactive surface. In the last few years, extensive efforts were made to design multifunctional nanoplatform strategies based on carbon nanostructures, involving multimodal imaging, controlled drug release capabilities, sensing in vitro, efficient drug loading capacity, and therapy. Carbon and graphene quantum dots (CQDs and GQDs) were the recent entrants, contingently being assessed for drug delivery and bioimaging. With the advancements, these quantum dots have ignited remarkable research interest and are now widely evaluated for diagnosis, bioimaging, sensing, and drug delivery applications. The last decade has witnessed their remarkable electrical, optical, and biocompatible properties since their inception. It is presumed that both of them have high potential as drug carriers and would serve as the next generation of approaches to address numerous unresolved therapeutic challenges. This review examined the recent advances of CQD and GQD based drug delivery applications, challenges, and future perspectives to pave the way for further studies in the future. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Journal of Physics is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With widespread industrial use of ammonia and its potential hazards to both human health and the environment, ensuring reliable detection has become paramount. In the present work, we report a study on a novel and highly sensitive gas sensing material, composed of carbon quantum dots (CQDs) for the detection of ammonia vapor at room temperature. The CQDs were synthesized at 200 °C using a hydrothermal single-step process. To investigate the morphology and chemical composition, CQDs were characterized by Fourier transform infrared spectroscopy, Transmission Electron Microscopy, photoluminescence, and UV–Vis spectroscopy. A thin-film of CQDs was then deposited on an ITO-coated glass substrate for the detection and quantification of ammonia vapor (NH3) by monitoring the response under ambient conditions. By corresponding change in conductance, the change in resistance of the film is investigated. The enhanced properties of sensing of the ammonia samples may be due to the combined effect of localized electronic surface states of CQDs and chemical sensitization caused by the catalytic properties of an active functional group on the CQDs surface. Notably, this sensor exhibits higher sensitivity, excellent response time, and greater stability to ammonia vapours compared to previous reports.

This study investigates the optical and structural properties of nitrogen-doped Carbon Quantum Dots (NCQDs) on Titanium dioxide (TiO2). We synthesized the NCQDs via direct pyrolysis using varying amount of nitrogen precursor. We used a UV-visible, Fluorescence and Fourier Transform Infrared spectrophotometer, X-ray diffractometer (XRD), and Scanning Electron Microscope (SEM) to probe the samples. The introduction of nitrogen enhanced the intrinsic activities and electron dynamics of the CQD films, leading to improved confinement, charge extraction, and light harvesting. The optical response of the NCQDs strongly hinged on the nitrogen doping content. Sensitizing different amounts of NCQDs on TiO2 surface reduced their bandgap energies. XRD analysis confirms the preservation of the TiO2 anatase phase nanoparticle after the introduction of NCQDs, with no substantial changes to the crystal lattice and phase purity of the resulting photoanodes, indicating the presence of NCQDs on the surface. However, the deposition of NCQDs decreased the crystallite size. SEM images show well-dispersed morphologies with non-clustered NCQDs films. NCQDs can serve as promising photosensitizers in photovoltaic devices. [ABSTRACT FROM AUTHOR]

Stable carbon quantum dots (CQDs) and Ni12P5 were synthesized by hydrothermal method and low temperature calcination method, respectively.The two materials were then combined into CQDS-Ni12P5 by simple mechanical grinding.The as-obtained catalysts were characterized by X-ray diffractometer (XRD), transmission electron microscope (TEM) and electrochemical impedance spectra (EIS), and the electron transfer behavior was measured by fluorescence (FL).Using dye Eosin Y (EY) as the catalyst (sensitizer), Ni12P5 as the cocatalyst and trimethylamine (TMA) as the sacrificial agent, the dye-sensitized hydrogen production performance of Ni12P5 modified by CQDs was studied.The results showed that Ni12P5 loaded with 15 wt% CQDs(15CQDs-Ni12P5) exhibited the highest dye-sensitized hydrogen evolution activity(3 565 μmol·h-1·g-1), which was 3.36 times higher than that of pure Ni12P5.The increased activity was due to the efficient electron transfer among EY,CQDs and Ni12P5.In addition, the possible mechanism of hydrogen evolution reaction was discussed. [ABSTRACT FROM AUTHOR]

In the case of CAU-17/Ag/CQDs, upon irradiation of the visible light, electrons in CAU-17/Ag can be excited from VB to CB. Owing to the high specific surface area and rich pore structure of the composite, the photogenerated electrons on the surface of CAU-17/Ag can be easily transferred to CQDs and be stabilized, consequently the chance for the recombination of electron-hole pair is greatly reduced. Instead, photogenerated electrons and holes may react with oxygen and water in the air to produce large amounts of ROS, •OH, and •O 2 –. These active substances induced by CAU-17/Ag/CQDs can directly attack bacterial cell membrane, cell envelope or intrinsiccell structures to impose rather a non-specific oxidative stress that potentially leads to the cell death. [Display omitted] • The prepared CAU-17/Ag/CQDs showed good photocatalytic antimicrobial activity. • Ag and CQDs promoted the formation of CAU-17 nanosheets, and Ag was uniformly dispersed on CAU-17 and CQDs to form a heterojunction. • CAU-17/Ag/CQDs can slowly release Ag+ and Bi3+. • CAU-17/Ag/CQDs have potential for tumor suppression. A composite based on Ag and carbon quantum dot (CQDs) doped bismuth metal organic framework (CAU-17) was synthesized by a one-step thermal solvent in situ growth. The microstructure, chemical composition, morphology, photogenerated electron-hole pairs, and photocatalytic activity of the composite were characterized. The produced composite with its unique energy band structure, enhances the visible light absorption and effectively delays the recombination of the photogenerated carriers. On the other hand, the modification with CQDs increases the concentration and transport rate of photogenerated carriers mainly attributed to their superior electron transport capacity and light trapping ability. The photocatalytic antibacterial effect of CAU-17/Ag/CQDs against common Gram-positive, Gram-negative bacteria (Staphylococcus aureus, Escherichia coli) and drug-resistant bacteria (methicillin-resistant Staphylococcus aureus), as well as its inhibition against HepG 2 tumor cell were investigated. The results showed that CAU-17/Ag/CQDs exhibited a photocatalytic antibacterial effect with an inactivation rate as high as 99.9 %. At the low dose (0.2 mg/mL), CAU-17/Ag/CQDs indicated a significant inhibition against bacterial growth 20 min after visible light exposure, whereas at the concentration of 0.5 mg/mL, CAU-17/Ag/CQDs completely killed all the tested bacteria. At the concentration of 0.8 mg/mL, the inhibition rate against HepG2 tumor cells reached 75 %. The excellent photocatalytic property of the as prepared composite contributed to the doping of Ag and CQDs, which fundamentally altered the morphology and energy band distribution. Such a composite can be developed into an effective photocatalytic disinfection system and applied to water purification systems, biofilm rejection, combating different antibiotic resistances, and tumor therapy. [ABSTRACT FROM AUTHOR]

Local bacterial infection remains an increasingly severe threat to human health worldwide, and infection control is still a challenging task. Carbon Quantum Dots (CQSs) and barium tungstate show antibacterial properties. CQDs doped Barium Tungstate (BaWO4) are synthesized by using a hydrothermal route and their optical and antimicrobial activities against the Gram-positive bacteria staphylococcus aureus and optical properties were investigated. The UV–Vis reveals a shift in the bandgap from 3.62 eV to 2.93 eV due to doping of CQDs in BaWO4. The structure of the CQDs/BaWO4 were studied by XRD, which shows CQDs doped BaWO4 samples possess tetragona4 werelite structure with the preferred orientation of (112) identified by XRD at 26° having crystallite size ∼ 31 nm. Nanocomposite BaWO4/CQDs exhibit a spherical-like shape and are composed of Ba, O, W and C according to the design of the experiment. Zeta sizer of CQDs by DLS shows the size of CQDs is 7.65 nm. The FT-IR shows the presence of functional groups in doped material like CC, CO, and COOH bonds which indicate that the C-dots are functionalized with epoxy, carbonyl, hydroxyl, and carboxylic acid groups. Their elemental composition and surface morphology were studied by EDS which shows the percentage variation of CQDs in BaWO4, SEM results show the change in shape of the sample by adding CQDs to BaWO4. The TEM image proves the presence of doped material in the BaWO4. The PL spectra reveals the emission spectra shift towards a higher wavelength and absorption increases. The qualitative analysis shows the antimicrobial activity and enlargement of the inhibition zone and quantitative analysis confirms it.

Alzheimer’s disease (AD) is a neurodegenerative disease that badly impacts patients and their caregivers. AD is characterized by deposition of amyloid beta (Aβ) and phosphorylated tau protein (pTau) in the brain with underlying neuroinflammation. We aimed to develop a neuroprotective paradigm by loading verapamil (VRH) into hyaluronic acid-modified carbon quantum dots (CQDs) and comparing its effectiveness with the free form in an AD-like model in rats induced by lipopolysaccharide (LPS). The experimental rats were divided into seven groups: control, LPS, CQDs, early free VRH (FVRH), late FVRH, early verapamil carbon quantum dots (VCQDs), and late VCQDs. Characterizations of VCQDs, the behavioral performance of the rats, histopathological and immunohistochemical changes, some AD hallmarks, oxidative stress biomarkers, neuro-affecting genes, and DNA fragmentation were determined. VRH was successfully loaded into CQDs, which was confirmed by the measured parameters. VRH showed enhancement in cognitive functions, disruption to the architecture of the brain, decreased Aβ and pTau, increased antioxidant capacity, modifiable expression of genes, and a decline in DNA fragmentation. The loaded therapy was superior to the free drug. Moreover, the early intervention was better than the late, confirming the implication of the detected molecular targets in the development of AD. VRH showed multifaceted mechanisms in combating LPS-induced neurotoxicity through its anti-inflammatory and antioxidant properties, thereby mitigating the hallmarks of AD. Additionally, the synthesized nanosystem approach exhibited superior neuroprotection owing to the advantages offered by CQDs. However, finding new actionable biomarkers and molecular targets is of decisive importance to improve the outcomes for patients with AD.

Phenol is a harmful substance that can cause pathological changes in animals or human body, and its degradation has become a research hotspot at present. This paper innovatively proposed the preparation of carbon quantum dots by microwave enhancement technology, the preparation of RuO 2 –TiO 2 -CQDs/Ti composite coating anode by thermal decomposition method, and studied the electrocatalytic degradation process of organic wastewater containing phenol. The surface morphology of the anode was observed by XPS, TEM and SEM. Electrochemical workstation was used to characterize the electrocatalytic performance of the anode, and high performance liquid chromatography was used to determine the degradation process. The results show that the doping of CQDs can produce a large number of vacancy defects on the surface of the composite coating, and the addition of CQDs can increase the loading of Ru element on the surface of the coating during anode preparation. With the increase of CQDs content, the crack width and depth of coating surface decrease gradually, and the crystal size decreases. Doping of CQDs can effectively improve the surface charge capacity and corrosion resistance of anode. Compared with the traditional RuO 2 –TiO 2 /Ti anode, the removal efficiency of phenol and COD at the RuO 2 –TiO 2 -CQDS/Ti composite coating electrode was increased by 102% and 55.7% respectively within 1 h. This study makes full use of the high specific surface area and excellent electrocatalytic performance of carbon quantum dots, which provides a new idea for the mineralization of high concentration phenol in Ru–Ti electrode. [ABSTRACT FROM AUTHOR]

In this (scenario) research work, the CQDs@g-C3N4 two-step-scheme nanocomposite was fabricated by a simple two-step hydrothermal/calcination process. The crystalline phase and morphological features of the materials were investigated by P-XRD, SEM, EDAX, and TEM. The designed CQDs@g-C3N4 nanocomposite was fruitfully formed, and the improved light absorption capability was tested with the photocatalytic activity of (Rhodamine B) RhB and (Ofloxacin) OFL. The CQDs@g-C3N4 nanocomposite shows enhanced activity in the degradation of RhB, and OFL and corresponds to a low recombination rate of charge carriers. Under optimized experimental conditions, the photocatalytic activities of pollutants (RhB & OFL) over CQDs@g-C3N4 can accomplish 94.3 and 99.5% within 30 and 60 min irradiation with visible light. The trapping experiments exhibited that O 2 · - , · OH , and intermediate mineralized compounds were involved in the catalysis process. Furthermore, the CQDs@g-C3N4 photocatalyst has remarkable storage stability after several consecutive runs. This research work presents a new platform for an effective route of heterostructures for environmental water contaminant treatments. [ABSTRACT FROM AUTHOR]

Upconversion nanoparticles (UCNPs) and carbon quantum dots (CQDs) have emerged as promising candidates for enhancing both the stability and efficiency of perovskite solar cells (PSCs). Their rising prominence is attributed to their dual capabilities: they effectively passivate the surfaces of perovskite-sensitive materials while simultaneously serving as efficient spectrum converters for sunlight. In this work, we synthesized UCNPs doped with erbium ions as down/upconverting ions for ultraviolet (UV) and near-infrared (NIR) light harvesting. Various percentages of the synthesized UCNPs were integrated into the mesoporous layers of PSCs. The best photovoltaic performance was achieved by a PSC device with 30% UCNPs doped in the mesoporous layer, with PCE = 16.22% and a fill factor (FF) of 74%. In addition, the champion PSCs doped with 30% UCNPs were then passivated with carbon quantum dots at different spin coating speeds to improve their photovoltaic performance. When compared to the pristine PSCs, a fabricated PSC device with 30% UCNPs passivated with CQDs at a spin coating speed of 3000 rpm showed improved power conversion efficiency (PCE), from 16.65% to 18.15%; a higher photocurrent, from 20.44 mA/cm2 to 22.25 mA/cm2; and a superior fill factor (FF) of 76%. Furthermore, the PSCs integrated with UCNPs and CQDs showed better stability than the pristine devices. These findings clear the way for the development of effective PSCs for use in renewable energy applications.

In this work, a series of clinoptilolite composites decorated with carbon quantum dots (CQDs/clinoptilolite) with hierarchical pore structures was demonstrated that exhibits good photocatalytic performance for the removal of xylene. The technique for the attachment of carbon quantum dots to clinoptilolite was prepared by a hydrothermal method in this study. The structural features were confirmed by SEM, TEM, EDS, XRD, BET, XPS, and solid diffuse reflection measurements, while the degradation mechanism was investigated by adding a trapping agent into the nanocomposites. The introduction of CQDs promoted the separation of photogenerated electrons and holes as well as the generation of reactive radicals, which effectively improved the light utilization and even increased the degradation rate of xylene by 73% at the optimal state. The photocatalytic test was conducted under a different dwell time, catalyst dosage, initial concentration, and illumination intensity. The results showed that the degradation rate of xylene by the CQDs/clinoptilolite catalyst reached 97.4% under the optimal reaction conditions (the catalyst was Catalyst No. 2, the residence time was 90 s, the initial concentration was 2.5 g/m3, the light intensity was three lamps for irradiation, and the catalyst dosage was 0.05 g). In addition, the degradation efficiency of the CQDs/clinoptilolite photocatalyst still reached 78% after eight consecutive catalytic regeneration cycles. This work sheds new light on the degradation of xylene. [ABSTRACT FROM AUTHOR]

Carbon Quantum Dots are stable photocatalyst which are synthesized from Spirulina platensis by microwave assisted technology. The synthesized CQDs contain rough surface and distributed in less than 10 nm size and exhibited strong blue fluorescence under UV transilluminator and PL spectra analysis. CQDs effectively degraded 150 ppm concentration of Reactive Blue MR, Reactive Orange M2A and Reactive Yellow M4G by the ratio of 1:10 (Catalyst and Dye) and required 4, 8 and 10 h for complete degradation, respectively. But in case of mixture of reactive dyes, 1:5 of catalyst and dye were used and it requires 10 h for complete degradation under sunlight. We also statistically studied optimized conditions for dye degradation using Response Surface Methodology for process parameters such as concentration, pH, volume, and time. The degradation reaction follows first order kinetics, and the removal of CQDs from treated water is attained by charcoal as an adsorbent. Modification of functional groups during dye degradation was analyzed by using FTIR. Various physico-chemical parameters such as BOD, COD, TOC, TIC and metal ions were studied to determine the quality of degraded water. 95% of various reactive dye can be effectively degraded by biosynthesized metal ion or chemical free natural CQDs. Hemolytic effect and cytogenetic effect of CQDs and treated water proved synthesized CQDs are non-toxic to living organism. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) are a new generation of QDs that have unique and interesting optical and structural properties. Fluorescence methods are useful, simple, and rapid for the detection of heavy metal ions in water, which has attracted great attention. In this research, a simple and rapid fluorescence method for the detection of cobalt (Co2+) ions in water is introduced. CQDs were synthesized by using pistachio as a precursor for the first time by a hydrothermal method. The QDs were characterized by structural analyses including x-ray diffraction, tunneling and scanning microscopies, energy-dispersive x-ray spectroscopy, infrared spectroscopy, BET surface area measurements, zeta potential measurements, and Raman spectroscopy. The Raman spectroscopy results showed a 3.54 value for the G/D ratio and this result confirmed that synthesized CQDs possess a graphitic crystalline structure. Zeta potential measurements confirmed the presence of a negative surface charge, resulting in high stability. These CQDs had blue photoemission with a broad PL peak between 300 to 600 nm. TEM images showed that CQDs are spherical with diameters of ∼7 nm. Their photocatalytic activities were studied with different dyes under both sun and UV light. Methylene blue had better degradation by the CQDs than methylene orange and Rhodamine B. The scavenger results indicate that radicals play a key role in the photocatalytic degradation of methylene blue under UV irradiation. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) were prepared by a green process (H2O2 chemical oxidation method) using the toluene solubles of high temperature coal tar pitch as the carbon source, and composite catalysts were synthesized with TiO2 and CQDs by hydrothermal deposition method. TEM, FTIR, XPS, XRD, UV-Vis and other techniques were used to characterize the morphology and structure of the two, and to explore the catalytic degradation effect of composite catalysts in the field of photocatalysis. The results show that the obtained CQDs have an average particle size of 1.33 nm, contain functional groups such as hydroxyl and carboxyl groups, have good water solubility, and have a fluorescence quantum yield of about 4.52%. The CQDs/TiO2 composite catalyst it shows better photocatalytic performance, the degradation efficiency of methylene blue (MB) can reach 82.7% within 2 h, which is significantly better than pure TiO2 (25.4%). [ABSTRACT FROM AUTHOR]

In this work, the application of carbon quantum dots as known as CQDs for ethanol detection is pioneered, and a multi-fold improvement in gas sensor performance is achieved through the unique electron transport mechanism of carbon quantum dots. The lychee-like SnO2 hollow microspheres and CQDs are prepared by a solvent heat method. The composites are assembled by rapid grinding, ultrasonication, and stirring. The minimum detection limit is 500 ppb. The response/recovery time of the best mass percentage composite is 9 s/16 s to ethanol at 100 ppm with an optimum working temperature of 216℃ in the target gas-sensitive test. Such a fast response speed improvement is ascribed to the excellent electron transfer efficiency of the 5 nm diameter carbon quantum dots (CQDs).

Polyimide (PI) is widely used in the field of microelectronics because of its excellent thermal, mechanical, optical, and electrical properties. With the development of electronics and information industry, PI as a dielectric material needs to possess low dielectric loss. PI/carbon quantum dots (PI/CQDs) composite films with low dielectric loss were prepared by introducing CQDs into PI matrix. At 25°C and 1 kHz voltage, the dielectric loss of pure PI film is about 0.0057. The dielectric loss of PI/CQDs composite film is about 0.0018, which is about 68% lower than that of pure PI film. The dielectric loss of PI/CQD composite film is greatly reduced while the mechanical properties and thermal properties of PI/CQDs composite film roughly remain unchanged. Due to the cross-linking structure formed between CQDs and PI molecular chain, the relative movement of PI molecular chain is hindered.

Quantum dots have found significant applications in photoelectric detectors due to their unique electronic and optical properties, such as tunable bandgap. Recently, colloidal quantum dots (CQDs) have attracted much interest because of the ease of controlling the dot size and low production cost. In this paper, a high-performance ZnO/PbS heterojunction photodetector was fabricated by spin-coating PbS CQDs onto the surface of a hydrothermally grown vertical array of ZnO nanowires (NWs) on an indium tin oxide (ITO) substrate. Under 940 nm near-infrared light illumination, the device demonstrated a responsivity and detectivity of ~3.9 × 104 A/W and ~9.4 × 1013 Jones, respectively. The excellent performances and low cost of this nanocomposite-based photodetector show that it has the potential for widespread applications ranging from medical diagnosis to environmental monitoring. [ABSTRACT FROM AUTHOR]

The development of a highly efficient, visible-light responsive catalyst for environment purification has been a long-standing exploit, with obstacles to overcome, including inefficient capture of near-infrared photons, undesirable recombination of photo-generated carriers, and insufficient accessible reaction sites. Hence, novel carbon quantum dots (CQDs) modified PbBiO2I photocatalyst were synthesized for the first time through an in-situ ionic liquid-induced method. The bridging function of 1-butyl-3-methylimidazolium iodide ([Bmim]I) guarantees the even dispersion of CQDs around PbBiO2I surface, for synchronically overcoming the above drawbacks and markedly promoting the degradation efficiency of organic contaminants: (i) CQDs decoration harness solar photons in the near-infrared region; (ii) particular delocalized conjugated construction of CQDs strength via the utilization of photo-induced carriers; (iii) π–π interactions increase the contact between catalyst and organic molecules. Benefiting from these distinguished features, the optimized CQDs/PbBiO2I nanocomposite displays significantly enhanced photocatalytic performance towards the elimination of rhodamine B and ciprofloxacin under visible/near-infrared light irradiation. The spin-trapping ESR analysis demonstrates that CQDs modification can boost the concentration of reactive oxygen species (O2•−). Combined with radicals trapping tests, valence-band spectra, and Mott–Schottky results, a possible photocatalytic mechanism is proposed. This work establishes a significant milestone in constructing CQDs-modified, bismuth-based catalysts for solar energy conversion applications. [ABSTRACT FROM AUTHOR]

In this work, a simple, continuous and completely green method based on microflow technique is demonstrated for the synthesis of carbon quantum dots (CQDs) from diverse bio‐based precursors. CQDs prepared from milk is illustrated as a case study to show the process feasibility. Crystalline fluorescent CQDs of 12.53% quantum yield and good stability are synthesized by the approach, even at 120°C. Systematic experiments further suggest their optical properties, bandgap energy, and fluorescence lifetime are closely related to the synthesis temperature. The maximum production rate of the CQDs was 51.1 mg/h at 180°C. Cytotoxicity and cellular imaging tests against 3T3 cells reveal the CQDs possess high biocompatibility, and can penetrate cell membranes and display bright fluorescence. The process versatility is investigated by expanding the precursor to watermelon juice, orange juice, and soy milk, indicating successful synthesis of small‐sized CQDs of low cytotoxicity and strong photoluminescence by the technique. [ABSTRACT FROM AUTHOR]

CQDs (carbon quantum dots) have attracted a lot of attention in the field of photocatalysis due to its absorption of visible light, up-conversion luminescence, rich free groups on the surface and low cost. CQDs doped semiconductor can improve the photocatalytic reaction rate by the following three points: (1) adjust the band structure of photocatalyst; (2) facilitate the absorption of more visible light; (3) facilitate electron transfer and inhibits electron-hole recombination. In this review, the mechanism (photosensitizer, electron acceptor, up-conversion luminescence, etc.) and applications (photocatalytic degradation of organic pollutants, reduction of heavy metals, etc.) of CQDs in the field of photocatalysis are briefly introduced. Finally, the factors affecting the photocatalytic activity were summarized in order to adjust the reaction conditions and show high catalytic activity. It is hoped that this review can provide insights and inspiration for the development of CQDs in the field of photocatalysis. [ABSTRACT FROM AUTHOR]

The removal of chlorophenol (CP) contaminants from water is a great challenge owing to their natural robustness and the toxic chlorinated by-products generated in degradation processes. In this work, a series of three-dimensional nanoflower-like structured photocatalysts (CQDs/ZnIn2S4-x, x = 1, 2, or 3 wt%) were fabricated via a facile hydrothermal approach. Excellent photocatalytic abilities toward 4-CP degradation under Xe lamp irradiation were achieved over the as-prepared composites. The removal efficiency of total organic carbon for 4-CP on the optimized CQDs/ZnIn2S4-2 was 49.1%, which was 16.0% higher than that of ZnIn2S4. The presence of CQDs could not only be used to adjust controllable band structures for enhancing light absorption, but it could also serve as an electron acceptor to promote the transition of electron–hole pairs. Moreover, a possible degradation mechanism of 4-CP was also proposed according to the analyses of active species, electron paramagnetic resonance characterization, degradation products, and attacked sites. Overall, this work unveils a superior function of an efficient photocatalyst for refractory organic pollutants. [ABSTRACT FROM AUTHOR]

The demand for lithium and its compounds is increasing by years, but separating lithium ions from brines are challenging. A novel material of Peach gum Carbon Quantum dots (PG-CQDs) lithium ion sieve was prepared by using a simple precipitation method and heat treatment. The molecular formula of the adsorbent compound was H 2.05 Mn 1.86 C 0.43 O 4 and the maximum adsorption capacity reached 34.6 mg/g, approximately twice that of the unmodified adsorbent, with a separation factor of 293.2–11434 in brine with a high Mg/Li ratio. Experimental and theoretical analyses indicated that he presence of Mn-O-C bonds in the adsorbent and that CQDs increase the pore structure of the lithium ion sieve and that the crystallisation of the original material changes, leading to an increase in BET surface area, proton number and adsorption capacity. The outstanding material can be massively used in lithium ions extraction in complex water system and carbon quantum dots doping Li+ sieve have potential application value for extracting lithium ions. [Display omitted] • A modified Li+ adsorbent PG-CQDs@HMS was obtained by co-precipitation. • Li+ adsorption capacity of PG-CQDs@HMS can reach to 34.6 mg/g. • PG-CQDs@HMS show a high Li+ selectivity with α Me Li of 293.2–11434 in brine. • CQDs increase the pore structure of the lithium ion sieve due to Mn-O-C bonds. [ABSTRACT FROM AUTHOR]

The CQDs/alkaline carbon nitride heterojunction photocatalysts were synthesized employing dicyandiamide as the nitrogen material, Citric acid was used as the carbon source, while KCl and NH 4 Cl were as alkaline reagents. The study investigated the influence of CQDs on the adsorption performance, photocatalytic activity, and band structure of alkalized carbon nitride. The dark adsorption results revealed that CNK/CQDs1: 12 exhibited outstanding adsorption performance, capable of degrading adsorbed pollutants in a relatively short period. The photocatalytic degradation study demonstrates that CNK/CQDs1:12 exhibits significantly higher degradation efficiencies compared to the pristine CN and alkalinized CNK samples, with degradation efficiencies of 94.4 % for Methylene Blue (MB) and 71.68 % for tetracycline hydrochloride (TC-HCl) within 60 min. This is due to the synergistic effects of alkalization of the g-C 3 N 4 surface and CQDs loading, which modified the heterojunction interfacial charge transfer efficiency, suppressing the recombination of photoelectron-hole pair, extending the life span of transient photogenerated carriers, thereby improving photocatalytic activity. Free radical trapping experiment indicated that h + and ·O 2 − are the primary active species during the photocatalytic degradation process of CNK/CQDs1:12. [Display omitted] • Surface alkalization and CQDs loading synergistic enhance photocatalytic activity CNK/CQDs heterojunction. • Outstanding adsorption properties of CNK/CQDs1:12 facilitate the photocatalytic degradation of contaminants. • Removal rate of CNK/CQDs1:12 on methylene blue and tetracycline hydrochloride were 94.4% and 64.4%, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • CQDs grown with Malva sylvestris. • CQDs are used as seeds for the hydrothermal nucleation and growth of ZnO. • CQDs/ZnO has a flower-like morphology. • Under the same hydrothermal conditions, ZnO nanosheets grow without Malva sylvestris. • CQDs/ZnO flowers demonstrate excellent methylene blue degradation. This study presents a new synthesis route to prepare ZnO flower-like particles. Firstly, carbon quantum dots (CQDs) were prepared hydrothermally, using the Malva sylvestris flower as the sole carbon source. Subsequently, flower-like particles of ZnO/CQDs were synthesized using CQDs seeds and the same hydrothermal process. The efficiency of the redox process of solar excitation was measured by reducing the dye methylene blue (MB). The SEM and TEM characterization shows ZnO flower-like particles of around 1.5 µm whose petals are formed by crystallites of around 10 nm. ZnO nanocrystals appear embedded in an amorphous carbon matrix. TEM images show carbon quantum dots on the surface of ZnO flowers. Without using Malva sylvestris , ZnO morphologies are not formed; instead, 2D nanolaminates appear. The ZnO/CQDs nanocomposite achieved 98 % MB degradation in 80 min. The small size of CQDs can be a good scenario for the growth of crystalline nanostructures using the nanocarbon seed. [ABSTRACT FROM AUTHOR]

NaYF 4 :Yb3+/Er3+Tm3+@TiO 2 -CQDs showed excellent upconversion luminescence performance and the efficiency of photovoltaic cells was enhanced by 3.10% under 1 sun intensity irradiation and 1.24% under infrared light (＞760 nm) irradiation. [Display omitted] • NaYF 4 :Yb3+/Er3+/Tm3+@TiO 2 -CQDs was developed as dual-upconversion luminescent material for photovoltaic cells. • Core@shell structure profit to enhance the upconversion luminescence intensity. • CQDs played a synergistic role in dual-upconversion with NaYF 4 :Yb3+/Er3+/Tm3+. • NaYF 4 :Yb3+/Er3+/Tm3+@TiO 2 -CQDs improved the utilization of infrared light. Rare-earth doped upconversion luminescence (UCL) is of great significance in improving the utilization of infrared (IR) light from solar radiation, especially in the efficiency enhancement of photovoltaic (PV) cells. However, the low level of luminescence efficiency remains a great challenge. Here, we designed NaYF 4 :Yb3+/Er3+/Tm3+@TiO 2 -CQDs upconversion luminescent materials. The construction of the core–shell structure and the loading of carbon quantum dots (CQDs) resulted in a 9-fold enhancement of upconversion luminescence and a 3.02% enhancement of the efficiency of the photovoltaic cell. These data indicate that the construction of the core–shell structure can effectively inhibit the surface quenching of the luminescent particles, and that the energy transfer between the carbon quantum dots and the rare earth ions has a synergistic effect on the efficiency enhancement of the photovoltaic cell. Meanwhile, the TiO 2 shell layer also enables the prepared materials to have better properties of self-cleaning and degradation of organic pollutants, which will further improve the visible light utilization of PV cells. NaYF 4 :Yb3+/Er3+/Tm3+@TiO 2 -CQDs provides new ideas for the practical application of PV cell efficiency enhancement and the design of new materials. [ABSTRACT FROM AUTHOR]

An efficient carbon quantum dot (CQD)-modified TiO 2 /SrTiO 3 heterojunction was constructed for photocatalytic CO 2 reduction in this paper. Photogenerated electrons of SrTiO 3 transferred to TiO 2 via the transfer channel of CQDs for electron-hole recombination, while the photogenerated electrons migrated from TiO 2 to CQDs to participate in the photocatalytic CO 2 reduction reaction. Meanwhile, the up-conversion of CQDs enhanced the light harvesting ability of the catalyst and the CQDs enriched the active reaction sites. Due to the above advantages, the CO and CH 4 produce rate over 0.1-CTS reached 54.9 and 35.9 μmol g−1 h−1, respectively, which was dramatically increased compared with pure TiO 2 and pure SrTiO 3. This work proposes a feasible strategy for integrating CQDs with TiO 2 and SrTiO 3 for the optimistic cooperative effect to obtain an effective catalyst for photocatalytic CO 2 reduction. [ABSTRACT FROM AUTHOR]

Ionic microenvironment of the nasal secretions especially calcium ions play essential role in the olfactory transmission. However, there is a critical need to determine the free calcium levels in healthy people's nasal secretions in contrast to those of patients with olfactory impairment. A selective spectrofluorometric method was created to quantify nasal calcium levels utilizing its quenching ability to the fluorescence of the functionalized carbon quantum dots. The surface of carbon quantum dots was functionalized with calcium ionophore A23187 and ion association complex, calcium phosphotungstate, to improve the selectively to quantify calcium ions. The functionalized carbon quantum dots exhibited a concentration-dependent fluorescence quenching upon interaction with calcium ions. Different factors influencing the quenching process were done to provide efficient analytical process. The new method, demonstrated accurate calcium determination over the concentration range of 200–4000 ng/mL. The suggested technique was used to measure the calcium in the nasal secretions of both healthy people and patients with olfactory impairment. The findings revealed significantly higher calcium levels in the patient with olfactory dysfunction (healthy vs. patient; 735 ± 20 ng/mL vs. 2987 ± 37 ng/mL, p < 0.05). [Display omitted] • Sensitive and selective spectrofluorometric method. • Functionalized carbon quantum dots. • Potential diagnostic tool for olfactory dysfunction. [ABSTRACT FROM AUTHOR]

The morphology and structure of photocatalytic materials often have a great influence on their photocatalytic performance. The photocatalytic degradation and hydrogen production capacity can be enhanced by optimizing the morphology and properties of the catalysts. In this paper, on the basis of carbon quantum dots (CQDs) with up-conversion photoluminescence (UCPL) properties and polystyrene colloid microspheres (PS) as templates, a kind of gully-like CQDs/In 2 O 3 /TiO 2 composites with wide spectral response was prepared by vacuum impregnation and microwave-assisted hydrothermal method. The results show that CQDs/In 2 O 3 /TiO 2 composites with PS colloid microsphere as templates have a gully structure, which provides more active sites for photocatalytic reaction. The heterostructure formed among components optimizes the charge transfer path, significantly improving the separation and transfer efficiency of photogenerated electrons and holes. In the multi-mode photocatalytic experiments, CQDs/In 2 O 3 /TiO 2 composites show excellent photocatalytic activity for methyl orange, of which photocatalytic activity is much higher than that of pure TiO 2 , displaying a certain degree of degradation for the different kinds of dyes. In addition, the hydrogen evolution capacity of CQDs/In 2 O 3 /TiO 2 composites is 1149.3 μmol/g for 8 h, which is 7 times of that of monomer TiO 2. The results of the capture experiments show that the possible photocatalytic mechanism of CQDs/In 2 O 3 /TiO 2 composites is more likely to be the result of a synergy between the traditional band theory and the "Z-scheme". The unique up-conversion characteristic of CQDs broadened the spectrum absorption range of gully-like CQDs/In 2 O 3 /TiO 2 composites, and the heterostructure between In 2 O 3 and TiO 2 accelerated the electron transfer, which jointly promoted the degradation of organic pollutants and the efficiency of photo-splitting water for hydrogen production. [Display omitted] • The gully-like CQDs/In 2 O 3 /TiO 2 composites were successfully prepared using polystyrene microspheres as the template. • The unique up-conversion characteristic of CQDs is used as an electron collector to extend the carrier life. • The heterojunction between In 2 O 3 and TiO 2 accelerates the electron transfer. • The unique gully-like structure provides more active sites for the reaction. • Photocatalytic hydrogen production activity of gully-like CQDs/In 2 O 3 /TiO 2 composites is much higher than that of TiO 2. [ABSTRACT FROM AUTHOR]

Urgent requirement for medication from cancer diseases and different microbial infections is interestingly considered. Carbon quantum dots (CQDs) as environmentally friendly fluorescent carbon nano-functionalized materials are popularly considered for application in medical purposes. Herein, a comparative study is presented for the affinity of CQDs ingrained from microcrystalline cellulose (MCC) prepared under hydrothermal conditions (CQDs-HT) versus that prepared under infrared assisted technique (CQDs-IR) for acting as anticancer and antimicrobial laborers. The estimated size averages for the obtained CQDs-HT & CQDs-IR were 7.8 & 9.8 nm, respectively. CQDs-HT showed rationally higher anti-proliferative action against Hepatocellular Carcinoma (HepG2) compared to CQDs-IR. Treatment with 1000 μg/mL of CQDs-IR & CQDs-HT exhibited 78 & 90 % mortality percentage of cancer cells, respectively. The obtained CQDs showed excellent microbicide potentiality and the minimum inhibitory concentration (MIC) from the synthesized CQDs-TH and CQDs-IR was ranged in 100–350 µg/mL and 300–400 µg/mL against different pathogens including bacteria and fungi, respectively. As a conclusion, hydrothermal technique showed seniority over infrared assisted technique in nucleation of CQDs with higher anticancer and microbicidal activities.

Highly fluorescent and water‐soluble carbon quantum dots (CQDs) were synthesized from the bio‐waste source of garlic peels (renovation of bio‐waste into bio‐asset) using a controlled carbonization method. Synthesized CQDs were characterized by various analytical methods and explored as a fluorogenic probe for the recognition of quercetin (QT). Ultraviolet‐visible (UV‐vis) result shows an absorption maximum at 275 nm attributed to the conjugation of C=C and C=O of CQDs and demonstrates a blue emission in the range 330–410 nm. Selectivity was performed with various biomolecules, except for QT, all others do not exhibit any considerable change in the fluorescence of CQDs. On the interaction with QT, emission was completely quenched due to Förster energy transfer (FET), confirming the high selective to QT. Effect of pH, sensitivity, and stability studies displayed excellent results under optimized conditions. The limit of detection (LOD) fluorescent probe was found to be 6.73 μM. Our approach may suggest a new platform for the development of quick and low‐cost CQDs‐based sensors for environmental and biological purposes. [ABSTRACT FROM AUTHOR]

[Display omitted] • An efficient ternary heterojunction photocatalyst CQDs/Bi/BiOBr was firstly prepared. • The interfaces of CQDs/Bi/BiOBr are combined by ohmic junction with low contact impedance. • DFT calculations reveal C-scheme electron transfer mechanism of CQDs/Bi/BiOBr. With a facile one-pot solvothermal method, an efficient ternary heterojunction photocatalyst carbon quantum dots (CQDs)/Bi/BiOBr is firstly prepared. Ethylene glycol (EG) is used as the solvent and carbon source for the first time. At 190 °C for 3 h, while BiOBr is synthesized, EG is employed to prepare CQDs through bottom-up method. CQDs are grafted by a large number of functional groups with reducibility, which reduce some neighboring BiO+ to metal Bi. By modifying the solvothermal temperature and time, CQDs and Bi are in-situ controllably deposited on the surface of BiOBr microspheres. Due to different Fermi levels and work functions, the interfaces of CQDs, BiOBr and Bi are connected through ohmic junctions with low contact impedance. The hot electrons from Bi with surface plasmon resonance (SPR) properties, and electrons in the CB of BiOBr flow to CQDs, forming a C-scheme electron transfer mechanism. O 2 − from CQDs and h+ in the VB of BiOBr respectively attack the sites with higher and lower electron density in methyl orange (MO) molecule, resulting in its photodegradation into small molecular products. [ABSTRACT FROM AUTHOR]

Surfactants are one of the major pollutants in laundry powder, which have an impact on the environment and human health. Carbon quantum dots (CQDs) are spherical zero-dimensional fluorescent nanoparticles with great potential for fluorescent probing, electrochemical biosensing and ion sensing. Herein, a bottom-up approach was developed for the synthesis of CQDs from biomass to detect laundry detergent and laundry powder. Waste chicken bones were used as carbon precursors after being dried, crushed and reacted with pure water at 180 °C for 4 h to generate CQDs, which exhibited a monodisperse quasi-spherical structure with an average particle size of 3.2 ± 0.2 nm. Functional groups, including -OH, C=O, C=C and C-O, were identified on the surface of the prepared CQDs. The optimal fluorescence excitation wavelength of the yellow-brown CQDs was 380 nm, with a corresponding emission peak at 465 nm. CQDs did not significantly increase cell death in multiple cell lines at concentrations of 200 µg·mL−1. Fluorescence enhancement of CQDs was observed after addition of sodium dodecyl benzene sulphonate, a major anionic surfactant in laundry powder. A linear relationship between fluorescence enhancement CQDs and the concentration of laundry powder was established. Thus, a hydrothermal method was developed to generate CQDs from waste biomass that may be used as a fluorescent probe to detect laundry powder. [ABSTRACT FROM AUTHOR]