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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]

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]

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]

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 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]

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]

Converting lignocellulosic materials to carbon quantum dots (CQDs) has garnered significant interest to transform biomass wastes into highly valuable products. We chose to use lignin as our feedstock because high-value products more readily utilize cellulose and hemicellulose. Lignin, arguably the most underutilized and complex biopolymer within any biomass, presents an appealing yet overlooked opportunity. While some may argue that lignin-based CQDs are no longer groundbreaking, this is because existing studies typically rely on commercially available lignin, ignoring biomass-derived sources. Therefore, in our pioneering research, we utilized organosolv lignin, prized for its structural purity and extracted from Moso bamboo waste, as the carbon source in a facile two-step technique to synthesize luminous CQDs. The process involved the addition of 2,4-diaminobenzenesulfonic acid, a mild-organic acid that acted as a source for both nitrogen (N) and sulphur (S). A 12-h hydrothermal treatment at 200 °C with 0.1 M of acid addition attained the best result. The resultant CQDs display strong green fluorescence, with the highest quantum yield of 17.7% seen in N and S co-doped CQDs. With their obvious and specific fluorescence quenching impact on Fe3+, CQDs demonstrate great potential as a fluorescent nanoprobe for metal ion detection. This CQD nanoprobe responds very sensitively to Fe3+ between 0 and 500 μM (R2 = 0.9803), with a detection limit of 0.15 μM. This research not only presents a unique alternative nanoprobe for the sensing field using renewable biomass lignin, but it also paves the way for the long-term, cost-effective, and scalable manufacturing of CQDs. [Display omitted] • Performed the synthesis of bio-based CQDs from bamboo-biomass lignin. • Doped with a mild organic acid additive, serving as N and S sources. • Unveiled potential as a potent green-fluorescent nanoprobe for Fe3+ detection. • Achieved 17.7% QY, responding to Fe3+ with a detection limit of 0.15 μM. • Paving way for a greener and scalable manufacturing of CQDs. [ABSTRACT FROM AUTHOR]

Sustainable use of agricultural waste still remains a challenging task. Herein, we used rice straw as a carbon precursor to prepare carbon quantum dots (CQDs) for photocatalytic applications. Nanocomposites of CQDs with Ti4+ and Mg2+ substituted strontium ferrite (Sr 0·4 Ti 0·4 Mg 0·2 Fe 2 O 4.4) nanoparticles (NPs) in varying w:w ratio was synthesized by ultrasonication method. The successful formation of nanocomposites was confirmed by various microscopic and spectroscopic techniques. The photocatalytic and antibacterial activity of NPs, CQDs and nanocomposites was comparatively evaluated using tetracycline hydrochloride, azure B, Staphylococcus aureus and Escherichia coli as model pollutants. The CQDs-Sr 0.4 Ti 0·4 Mg 0·2 Fe 2 O 4.4 nanocomposite with a w:w ratio of 2:1 showed excellent photocatalytic and antibacterial activity, with the degradation and inactivation efficiency ranging from 97.1% to 99.0% in presence of visible light. The increased specific surface area (117.2 m2/g), and reduction in band gap (2.48 eV–2.09 eV) and decreased photoluminescence intensity of nanocomposites all corroborated these results. The impacting experimental parameters such as catalyst dose, pH and contact time were also examined. Quenching experiments confirmed that hydroxyl radicals (HO ∙) radicals and holes (h+) played a vital role in the degradation of pollutants. The kinetics of photodegradation was explained by using the Langmuir-Hinshelwood model. Box-Behnken statistical modelling was used to optimize photocatalytic parameters. Results indicated that the nanocomposite of CQDs with Sr 0·4 Ti 0·4 Mg 0·2 Fe 2 O 4.4 can serve as a promising photocatalyst for the removal of pollutants and microbes. [Display omitted] • Heterostructural nanocomposites of rice straw CQDs with substituted SrFe 2 O 4 were synthesized. • Nanocomposite having 2:1 ratio of CQDs-Sr 0.4 Ti 0·4 Mg 0·2 Fe 2 O 4.4 displayed excellent photocatalytic and antibacterial activity. • The quenching study helped in predicting the reactive oxygen species in photocatalytic degradation. • Photocatalytic and antibacterial mechanism was proposed. • Box-Behnken statistical model was used to optimize photocatalytic parameters. [ABSTRACT FROM AUTHOR]

Schematic illustration of dual channels detection of LPS based on Fe-C QDs@Poly B. (a) Construction of the Fe-C QDs@Poly B with extraordinary specificity for LPS. (b) Illustration of the dual channels system in analysis of LPS. [Display omitted] • A novel nanozyme with excellent fluorescent property had been prepared. • Dual channel sensing platform was constructed for precisely quantification of LPS. • The weakness of negligible selectivity was avoided by combination. • The complementary method redeemed the poor sensitivity of colorimetric method. • Highly efficient analytical platform was constructed with the fluorescent nanozyme. The release of lipopolysaccharide (LPS) during the proliferation and death of bacterial growth could cause acute versatile disorders like anaphylaxis and multiple organ failure. Analysis methods with high sensitivity and selectivity are expected to be developed to replace the limulus lysate test. Classical colorimetric method was equipped with portable visualization but limited with low sensitivity, while incredibly sensitive fluorescence sensing strategy suffered from negligible selectivity. Delicate design of the dual channels analysis would make the ends of such dilemma based on a fluorescent nanozyme of iron doped carbon quantum dots (Fe-CQDs) with both excellent fluorescence and peroxidase-mimic catalytic activity. Accordingly, a complementary dual channel analytical platform of LPS was prepared. The excellent peroxidase-like activity imparted the dominant selectivity for LPS (available under 6 interferences), while the powerful fluorescence property endowed the excellent sensitivity with the limit of detection (LOD) of an unprecedented level (0.0023 EU/mL). Our study has broadened a new path for design of efficient analytical methods via complement way. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of carbon quantum dots were prepared using persimmon frost as a carbon source. • Fe,S,N/CQDs exhibits excellent peroxidase-like activity. • A Fe,S,N/CQDs−based colorimetric sensor was proposed for detection of UA. • The proposed sensing system is an attractive candidate for simple and fast detection of UA. A green and rapid method was developed to synthesize a series of carbon quantum dots (Fe,N/CQDs, Fe,S/CQDs, S,N/CQDs and Fe,S,N/CQDs) through thermal decomposition using persimmon frost as a carbon source. All the synthesized CQDs have peroxidase-like activity, and the comparision of their steady-state kinetic parameters inferred that the peroxidase-like activity of Fe,S,N/CQDs is superior to those of Fe,S/CQDs and Fe,N/CQDs. Furthermore, Fe,S,N/CQDs exhibited good affinity towards 3,3′,5,5′-Tetramethylbenzidine (TMB) and H 2 O 2 compared to natural horseradish peroxidase (HRP) and other nanozymes. In theory, uric acid (UA) can produce H 2 O 2 with the catalysis by uricase. Fe,S,N/CQDs could catalyze the breakdown of H 2 O 2 to produce reactive oxygen species (ROS), which can oxidize TMB (colorless) to oxTMB (blue). Based on the nanozyme-catalyzed oxidation of TMB, a simple and sensitive colorimetric sensor was developed for the quantitative analysis of H 2 O 2 and UA. Low limit of detection (0.73 μM), wide linear range (1–80 μM) and good repeatability were obtained. The sensor was also demonstrated for the determination of UA in biological samples and satisfactory results were obtained. [ABSTRACT FROM AUTHOR]

BiOBr can effectively mitigate the ecological and environmental problems caused by pollution with antibiotics, and its photocatalytic properties can be improved by utilizing heterojunction structures and cocatalysts. In this study, the Z-scheme heterojunction ternary photocatalyst BiOBr/g-C 3 N 4 /CQDs (BCC x) was obtained by using an uncomplicated electrostatic self-assembly process. The incorporation of carbon quantum dots (CQDs) with high conductivity provided a conduit for charge transfer between g-C 3 N 4 and BiOBr. The loading density of CQDs on BiOBr/g-C 3 N 4 could be rapidly adjusted by changing the concentration of the CQDs precursor in solution. The presence of CQDs enhanced the absorption of visible light and inhibited the synthesis of photogenerated charge carriers, thereby resulting in a synergistic effect on the Z-scheme heterojunction and improving the photocatalytic properties under visible light. In particular, BCC50 had the highest catalytic performance, with a tetracycline pollutant degradation efficiency of 100% within 60 min. The degradation efficiency remained above 95% even after repeated use in five cycles. The principles of semiconductor energy bands and internal electrostatic field generation are applied to explain the photocatalytic mechanism responsible for tetracycline degradation using BiOBr/g-C 3 N 4 /CQDs. [Display omitted] • Novel Z-scheme BiOBr/g-C 3 N 4 /CQDs photocatalysts are fabricated. • CQDs-BiOBr/g-C 3 N 4 improves light harvesting and facilitates e−-h+ separation. • CQDs are favorable for transfer of charge carriers and light absorption ability. • BiOBr/g-C 3 N 4 /CQDs can effectively remove Tetracycline (TC-HCl) under the light. • The photocatalytic performance of BiOBr/g-C 3 N 4 /CQDs is related to the addition amount of CQDs solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • The CQDs are introduced for the synthesis of high performance PUU. • The CQDs can enhance the crosslinking of the PUU and the formation of the Hydrogen-bonds. • The addition of CQDs can greatly improve the mechanical and self-healing properties of PUU. • The nanocomposite materials PUU-CDx have excellent self-healing and recyclable properties. Developing high-performance polymer composites with self-healing and recyclable performance is crucial for long-term durability of the devices. This paper presents a novel method by incorporating carbon quantum dots (CQDs) into the chain extension reaction of polymers to construct self-healing polyurethane-urea (PUU) with excellent integrated mechanical and multi-recyclable properties. By the introduction of the CQDs with surface containing ample amide, carboxyl, and hydroxyl groups, the cross-linking networks are formed, and simultaneously, abundant H-bonds at the interface between CQDs nanospheres and PUU matrix provide strong interfacial interactions, which endows material reinforcement and self-healing effect. The addition of a very low amount of CQDs (0.15 wt%) can significantly improves the mechanical performance, especially the tensile stress and toughness, which increased about 74.4 % (35.2 MPa to 61.4 MPa) and 115.2 % (34.8 MJ·m−3 to 74.9 MJ·m−3), respectively. Besides, unlike other nanofillers, the addition of CQDs (more than 1 wt%) enables the PUU with excellent self-healing and recycling properties, and for 3 wt% addition, the room temperature self-healing efficiency can even achieve 97.0 % for 24 h without external intervention. Furthermore, the addition of the CQDs can also significantly the damping effect of the polymers. It is highly anticipated that the research will provide a facile method to construct high performance polymer materials. [ABSTRACT FROM AUTHOR]

[Display omitted] 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 (BaWO 4) 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 BaWO 4. The structure of the CQDs/BaWO 4 were studied by XRD, which shows CQDs doped BaWO 4 samples possess tetragona4 werelite structure with the preferred orientation of (1 1 2) identified by XRD at 26° having crystallite size ∼ 31 nm. Nanocomposite BaWO 4 /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 BaWO 4 , SEM results show the change in shape of the sample by adding CQDs to BaWO 4. The TEM image proves the presence of doped material in the BaWO 4. 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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon quantum dots (CQDs) are versatile nanomaterials, showcasing unique properties for diverse applications. • The review covers a spectrum of synthesis techniques, emphasizing diverse structures and properties of CQDs. • From traditional bottom-up to innovative top-down approaches, synthesis strategies influence the physicochemical properties of CQDs. • The paper explores CQDs' exceptional performance in the evolving landscape of bioimaging applications. • The comprehensive review serves as a valuable resource, offering insights for researchers into CQD synthesis, characterization, and bioimaging applications. Carbon quantum dots (CQDs) have gained substantial attention as multifunctional nanomaterials with distinctive characteristics, positioning them as highly promising candidates across various applications. This article presents a thorough examination of the techniques used in synthesizing and characterizing CQDs, with a focus on their varied structural and chemical compositions. The diverse synthesis methods encompass a broad spectrum of approaches, from traditional bottom-up techniques to innovative top-down strategies, each exerting influence over the physicochemical properties of CQDs. In addition, this review delves into the ever-expanding realm of bioimaging applications, showcasing the exceptional performance of CQDs. It also underscores recent breakthroughs in comprehending the underlying mechanisms of CQD bioimaging, shedding light on the interactions between CQDs and biological systems. Moreover, a critical analysis of present challenges and future prospects in this domain is provided, paving the way for the rational design and advancement of sophisticated CQDs for bioimaging applications. This comprehensive review serves as an invaluable reference for researchers, offering profound insights into the synthesis, characterization, and bioimaging applications of CQDs. [ABSTRACT FROM AUTHOR]

Photocatalysis, a sustainable development strategy, employed to produce value-added chemicals from lignin, has attracted much attention due to its low energy consumption and mild reaction conditions. Carbon quantum dots (CQDs) and tungsten oxide (WO 3) composite photocatalysts (CQDs/WO 3) were prepared by ultrasonic assisted wet impregnation method in this study. The CQDs/WO 3 nanosheets exhibit good optical properties and satisfactory performance of lignin depolymerization. Characterization results embody that the addition of CQDs significantly changes the morphology of WO 3. Compared with bulk pure WO 3 , CQDs/WO 3 becomes a nanosheet structure in the size of ∼ 200 nm. Furthermore, CQDs can absorb photogenerated electrons as well as reduce the recombination of photogenerated electrons and holes. The strong oxidizing ability of n -type semiconductor WO 3 enables it to effectively break the typical bonds like C-O or C-C near polar functional groups in lignin. Due to this ingenious design, dealkaline lignin conversion was up to 34.21% as well as the highest yields of vanillin and vanillic acid in the form of lignin were 24.74 mg/g and 8.02 mg/g in 2 h at room temperature, visible light illumination and air atmosphere, respectively. And optimized CQDs/WO 3 also had satisfactory effects on three natural lignin (grass lignin, pine lignin and birch lignin), which proved its universality. Electron spin resonance experiments and mechanism investigation demonstrated that ·O 2 - and ·OH play a weighty role in photocatalytic depolymerization of lignin. This study provides a new gambit for converting lignin to high value-added chemicals (vanillin and vanillic acid) over modified WO 3. [Display omitted] • The photocatalyst was synthesized by a simple preparation method. • Carbon quantum dots can collect and release electrons as an electronic medium, which promotes the separation of photogenerated carriers. • The obtained high value-added chemicals have high yield. • Photocatalysts have good effects on commercial lignin and natural lignin. • It was confirmed that ·OH and ·O 2 -played a key role in the catalytic depolymerization of lignin. [ABSTRACT FROM AUTHOR]

In this work, novel porous g-C 3 N 4 nanosheets modulated by up-conversion carbon quantum dots (CQDs/CNS) were successfully fabricated. Using the photocatalytic inactivation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as the model reaction, the visible light-triggered antibacterial activity was evaluated. It was found that the photocatalytic performance towards bacterial inactivation is significantly improved, with the minimum inhibitory concentration (MIC) in CQDs/CNS against E. coli and S. aureus only being 12.5 and 40 ppm, respectively. The enhancement in antibacterial behavior can be attributed to the introduction of up-conversion CQDs. On the one hand, it extends absorption region to the visible light which promotes the generation of e- - h+ pairs. On the other hand, it narrows the energy band gap which accelerates the separation of carriers and transferance of charges at the interface. This study provides a new insight for developing a CQDs-based g-C 3 N 4 system for effective bacterial disinfection. [Display omitted] • The CQDs/CNS were fabricated by hydrothermal strategy. • The CQDs possess unique up-conversion photoluminescence properties. • The MIC of CQDs/CNS against E. coli and S. aureus is 12.5 and 40 ppm, respectively. • The enhanced bactericidal effect is attributed to the extension of light absorption region and the decline of energy bandgap. [ABSTRACT FROM AUTHOR]

Utilization of up-conversion materials is an effective strategy to realize near-infrared (NIR) light driven photocatalysis. However, their wide emission range lead to the low utilization efficiency of near-infrared light. In this paper, carbon quantum dots (CQDs) and NaYF 4 : Yb3+, Tm3+ (NYF) are used to construct efficient photon conversion channel, which could realize effective utilization of NIR light via dual-upconversion process. Under 980 nm laser light irradiation, NYF emits discontinuous light in the range of 292–805 nm. Only lights below 519.8 nm can be absorbed by Ag 3 PO 4 directly. The lights above 519.8 nm are also utilized by Ag 3 PO 4 after the secondary conversion of CQDs. Such secondary light conversion significantly promotes the NIR light utilization efficiency by Ag 3 PO 4. This work provides a new insight into designing and constructing superior photocatalyst by dual photon conversion channel for NIR light utilization. Image 1 [ABSTRACT FROM AUTHOR]

A composite material of CQDs@CdIn 2 S 4 /CdS modified by carbon quantum dots (CQDs) with up-conversion property was prepared by the microwave assisted method. CQDs@CdIn 2 S 4 /CdS composites consisting of hexagonal phase CdS and cubic phase CdIn 2 S 4 show a uniform flower spherical-like morphology and a significant increase in specific surface area. Moreover, the prepared CQDs with up-converted photoluminescence property can convert long wavelength light (λ > 600 nm) into short wavelength light (λ < 600 nm), which can match the light absorption range of the composite CdIn 2 S 4 /CdS reasonably, broaden its light response range and improve its utilization of sunlight. At the same time, the photocatalytic activity of CQDs@CdIn 2 S 4 /CdS series composites under different light sources was studied with methyl orange as the model molecule, and 1% CQDs@CdIn 2 S 4 /CdS was determined as one of the best photocatalytic material. The composite material 1% CQDs@CdIn 2 S 4 /CdS not only had high photohydrogen production capacity (3177.8 μmol/g, 8 h), but also had a very stable effect on the ultraviolet photocatalytic degradation rate and the final hydrogen evolution yield of photolyzed water after four cycles. • Flower spherical-like CQDs@CdIn 2 S 4 /CdS was prepared by microwave-assisted method. • CQDs with up-conversion property can convert long wavelength light into short wavelength. • The light absorption range of CQDs and CdIn 2 S 4 /CdS was reasonably matched. • 1%CQDs@CdIn 2 S 4 /CdS had high photodegradation and photohydrogen production capacity. • CQDs act as spectral converters, electron transport mediators and acceptors. [ABSTRACT FROM AUTHOR]

• The H-mSiO 2 -BiOI/CQDs hybrid materials was constructed. • The effective electron transfer mechanism is formed in the H-mSiO 2 -BiOI/CQDs heterointerface. • The photoinduced carriers recombination is effectively suppressed by the synergetic effect of several factors. • The stable and high photocatalytic activity was achieved by the H-mSiO 2 -BiOI/CQDs composite. In this paper, H-mSiO 2 -BiOI/CQDs hybrid materials were synthesized successfully via a facile method. Afterwards, the structures, morphologies, optical properties and photocatalytic performances of the prepared materials were investigated by multiple techniques. This research showed that the H-mSiO 2 -BiOI/CQDs materials demonstrated obviously improved photocatalytic performance compared with BiOI. In the photocatalysis process of rhodamine B (RhB) under visible light irradiation, the optimum photocatalytic performance would be obtained when the content of BiOI and the weight percentage of CQDs was appropriate. In this photocatalytic system, the enhanced photoactivity was mainly attributed to the synergistic effects of the huge BET surface area of H-mSiO 2 , multiple reflections of the internal cavities of H-mSiO 2 , facilitation of the reactant molecules transfer, efficient e−-h+ pair separation via CQDs, and the up-converted PL property of CQDs. The radical trapping experiments revealed that O 2 •−, e− and h+ were the main active species during the photocatalysis process. A possible mechanism of H-mSiO 2 and CQDs for the enhancement of visible light performance was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A ratiometric probe with higher stability was prepared with natural substances. • Fluorescence inner filter effect was triggered between SCQDs and Cur in Fe-MOFs. • Fe2+ from MOFs was ably used to capture active sites of Cur to avoid interference. • The developed probe shows high sensitivity to SA with LOD as low as 0.14 μmol/L. Herein, a ratiometric fluorescent probe was developed for sensitive detection of salicylic acid (SA) in rice using silk-derived carbon quantum dots @ Curcumin @ iron-based metal organic framework (SCQDs@Cur@Fe-MOFs). Fe-MOFs with porous structure not only provided holes for SCQDs to evade self-aggregation of SCQDs, but Fe2+ ions from MOFs was ingeniously employed to capture active sites of Cur, solving the problem of lacking sufficient specificity of Cur to SA while converting weak response signal to amplified "turn on" mode. Upon exposed to SA, the probe interacted with SA to form Cur-Fe2+-SA ternary complex, which inhibited the internal filtration effect between Cur and SCQDs, and triggered a cascade of response signaling. With this strategy, the proposed probe achieved sensitive determination of salicylic acid in rice with detection limit as low as 0.14 μmol/L. This study provides unique insight into constructing economical and eco-friendly fluorescent sensor for SA detection with superior performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Critical characteristics of CQDs support their applications as electrocatalysts. • Hybrid materials are being studied to improve CQDs for water splitting. • Candidates identified for conjugation hint at water splitting's commercial potential. • Encapsulating CQDs, nanoparticles deliver exceptional OER and scalable pyrolysis. • CQDs synthesis using bottom-up method produces green energy. • Future challenges to the hydrogen economy are clearly identified. The recent advances in nanomaterials have led to speculation about the effectivity of carbon quantum dots applied as electrocatalysts for water splitting. An insufficient amount of research has been undergone into this proposed application, although CQDs exhibit great potential with rapid electron transfer rates, long-term stability and desirable morphologies. To evaluate various materials that could aid CQDs in their application as electrocatalysts for water splitting, investigate environmentally conscious synthesis routes and determine whether the application could be considered for commercial applications, numerous studies and articles were collated to obtain a comprehensive strategy for processing and analysing data. Further, investigating not only CQDs but metal alloy nanoparticles, along with their current uses and the other supporting materials they have been conjugated with, contributes to the significance to this work. Focusing on the extrapolated results of over potentials, current densities and production rates of both hydrogen and oxygen throughout electrolysis is of utmost importance. Notably, CQDs exhibited low Tafel slopes (35–45 mV/dec), along with crucial traits such as stability and rapid electron transfer rates, affirming their potential as electrocatalysts. Among the various metal alloy nanoparticles investigated, suitable candidates for conjugation were identified. Collectively, the collated data suggests that a CQD/metal alloy nanoparticle conjugation could enhance the water splitting process for commercial applications, particularly in the underexplored realm of hydrogen production. However, it remains imperative to perform experimental procedures to substantiate this proposition when feasible. [ABSTRACT FROM AUTHOR]

[Display omitted] • CQDs/AuNPs were synthesized and thoroughly characterized by XRD, XPS, IR, UV–Vis and TEM. • Linear increase of fluorescence intensity recovery with amikacin concentration. • Wide linear range from 10-10 to 10-8 M, high accuracy, very low LOD of 0.02 ppb. • High selectivity for amikacin detection towards different commonly antibiotics. • Successfully applied for amikacin detection in drugs and surface water samples. Amikacin is an aminoglycoside antibiotic widely used to treat various bacterial infections in humans. However, elevated concentrations of amikacin can damage the cochlear nerve. Thus, accurate and rapid amikacin detection is crucial. In this study, we developed an "on-off" fluorescence nanosensor for highly sensitive amikacin determination based on a composite of carbon quantum dots (CQDs) and gold nanoparticles (AuNPs). The method quenches CQD fluorescence (turn-off) when they bind to AuNPs but restores it (turn-on) when amikacin binds and releases the CQDs. Adding Cu2+ enhances sensitivity by cross-linking amikacin-coated AuNPs. Under optimal conditions (pH 4, 1 mM Na 2 SO 4 , 1 mM CuSO 4), the method achieved a low detection limit of 3.5 × 10-11 M (0.02 ppb), a wide linear range (10-10 to 10-8 M), high precision (RSD < 5 %), and a rapid 2-minute response time. Exceptional selectivity was observed over other antibiotics. The CQDs/AuNPs-based sensor successfully detected amikacin in pharmaceutical and surface water samples. This approach offers a fast on-site analytical method for amikacin detection, with potential applications in clinical and environmental settings. [ABSTRACT FROM AUTHOR]

Since the beginning of 21th century, nanoscience and nanotechnology become the most promising topics in various fields, attributing to the superior characters of nanoscaled structures. The conventional quantum dots are substituted with new family of luminescent nanostructures, owing to their interchanged optical properties, low-cost of fabrication, biocompatibility, non-toxicity, ecofriendly, hydrophilicity and superior chemical stability. Carbon quantum dots (CQDs) were recently investigated for their simple synthesis, bio-consonance, and different revelation applicability. Obeying the green chemistry aspects, this review demonstrates an overview about CQDs generated from polysaccharides in brief, with a background on CQDs discovery, chemical composition, green synthesis via exploitation of different polysaccharides (cellulose, starch, pectin, chitin, etc) as biocompatible/biodegradable abundant biopolymers. Additionally, applications of CQDs originated from polysaccharides in environmental purposes, textiles industry and medical activities were also presented. [Display omitted] [ABSTRACT FROM AUTHOR]

The multi-dimensional integrated methods have been explored for fabrication of CQDs/CeO 2 /PbFe 12 O 19 (CQDs/CO/PFO) photocatalysts with the different CQDs contents. A variety of structural and component characterization methods have been adopted to study the phase purity and composition of CQDs/CO/PFO photocatalysts, which does not contain any other impurities except the basic constituent substances. The microstructure and optical behavior proved the formation of heterojunction between CQDs, CO and PFO, and the absorption edge was significantly red shifted compared with the CO and CO/PFO photocatalysts. The experimental results show that the CQDs/CO/PFO photocatalyst has high photocatalytic rates for the degradation of oxytetracycline hydrochloride (OTC-HCl) under simulated sunlight irradiation. The photocatalytic efficiency of CQDs/CO/PFO photocatalysts is not linearly dependent on the content of CQDs, optical absorption coefficient, energy band (Eg) value and magnetic properties. The optimal CQDs content, the magnetic squareness ratio (SQR), the initial drug concentration, the catalyst content and initial pH value were 7 mL, 0.271, 50 mg/L, 1 g/L and 10, respectively. A variety of free radical verification experiments, degradation pathways and toxicity analysis confirmed that the hole (h+) and hydroxyl radical (•OH) were the two primary active species in CQDs/CO/PFO photocatalysts for the degradation of OTC-HCl. The multi-dimensional integrated methods have been explored for fabrication of CQDs/CeO 2 /PbFe 12 O 19 photocatalysts with the different CQDs contents. The CQDs/CeO 2 /PbFe 12 O 19 photocatalysts present excellent photocatalytic rate for degradation of oxytetracycline hydrochloride under simulated sunlight irradiation. [Display omitted] • The CQDs/CeO 2 /PbFe 12 O 19 photocatalysts were fabricated by the multi-dimensional integrated methods. • The photocatalysts present excellent photocatalytic rate for the degradation of OTC-HCl. • Possible photocatalysis mechanism and degradation pathway have been proposed. [ABSTRACT FROM AUTHOR]

• A CQDs/MIL-101(Fe)/g-C 3 N 4 composite photocatalyst was successfully prepared. • The existence of CQDs promoted the movement of photogenerated electrons in CQDs/MIL-101(Fe)/g-C 3 N 4. • Type-II and Z-scheme heterojunctions may be present in the CQDs/MIL-101(Fe)/g-C 3 N 4 composite simultaneously. In this work, CQDs/MIL-101(Fe)/g-C 3 N 4 photocatalyst was facilely fabricated, which exhibited prominent photocatalytic properties for the degradation of methylene blue (MB) aqueous solution. The photocatalytic degradation rate of MB by CQDs/MIL-101(Fe)/g-C 3 N 4 composite material was found to be 124.7 times higher than that of MIL-101(Fe) and 1.3 times higher than that of MIL-101(Fe)/g-C 3 N 4. Based on the different positions of CQDs in the structure, it is proposed that both Type-II and Z-scheme heterostructure models may exist simultaneously in the CQDs/MIL-101(Fe)/g-C 3 N 4 composite material. The enhancement mechanism of CQDs in promoting the migration and separation of visible light-generated carriers in the ternary composite material is under discussion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Emissive CQDs were obtained from waste of beetroot fruit. • Use of beetroot bagasse as natural source for synthesis of CQDs offers a solution from biomass waste disposal problem. • Carbonization of organic waste allows surface passivation of CQDs. • Diminishing of luminescent properties could be related with adsorption of metallic ions. Water-dispersible and fluorescence-stable carbon quantum dots (CQDs) have been synthesized from waste Beetroot fruit (bagasse) through a low-cost synthesis-functionalization process at different times and temperatures of carbonization. At 254 nm of excitation, the obtained CQDs have emission in different colors: light purple, yellow and blue. By FT-IR analysis was determined that carbonyl groups from betalainic compounds present in beetroot fruit were responsible of surface passivation and consequently the presence of photoluminescent properties. Raman spectroscopy showed that the obtained CQDs are mainly made up of sp2 graphitic carbon with sp3 carbon defects and oxygen functional groups. The obtained CQDs were used in model Cu2+ and Ag+ solutions with the aim to study relationship of time and temperature carbonization with decrease of intensity emission to stablish their potential use as a sensor of metallic ions. The novelty of this work lies in obtaining CQDs by organic waste, which offers a solution from biomass waste disposal problems, especially in developing countries where these wastes are increasing considerably, and in addition the obtained product can be used as a metal ions sensor. [ABSTRACT FROM AUTHOR]

Herein, FeTiO 3 perovskite particles were functionalized with carbon quantum dots (CQDs) using ultrasonication followed by impregnation methods. The functionalization enhanced visible light-driven degradation of ciprofloxacin (CIP) antibiotic via extended light absorption, promoted separation rate of photogenerated carrier and increased oxygen vacancies. The FeTiO 3 /CQDs composite including 20 mL of CQDs degraded 68.4 % of CIP within 120 min whereas FeTiO 3 itself only degraded CIP by 36.5 %. On the basis of the structural characterization, the successful introduction of CQDs was confirmed in the FeTiO 3 /CQDs composite. The increased ratio of oxygen species was proved by XPS and ESR measurements, and the improved charge transfer was supported by PL analysis. The degradation mechanism was identified via scavenger tests; super oxide radicals and holes were found dominant in the degradation reaction. Furthermore, the photocatalytic performance was boosted by adding two Fenton reagents to the reaction environment. The FeTiO 3 /CQDs composite catalyst also exhibited an excellent reusability and stability features. Accordingly, this study presented a novel and low-cost hybrid semiconductor as efficient and sustainable material for environmental purification under visible light irradiation. [Display omitted] • FeTiO 3 was firstly functionalized with carbon quantum dots (CQDs). • Modified FeTiO 3 exhibited higher photocatalytic ciprofloxacin degradation. • Efficient charge transfer feature of CQDs boosted photocatalytic activity. • Increased oxygen vacancies were confirmed by XPS and ESR analyses. [ABSTRACT FROM AUTHOR]

[Display omitted] • The UV PD was constructed face-to-face from TiO 2 NRs: CQDs/FTO and PEDOS/FTO. • Sensitization of TiO 2 NRs by CQDs enhances the pyro-phototronic effect of TiO 2 NRs. • CQDs and PEDOS interact with each other and have matching energy levels. • The photovoltaic-pyroelectric coupled effect enhanced the performance. • The UV PD have high responsivity and detectivity in the self-powered model. TiO 2 -based ultraviolet (UV) photodetectors (PDs) with broadband optical detection range are widely used in commercial and military applications. Nevertheless, the self-powered UV PDs of TiO 2 nanoarrays (NRs) have relatively low response rates and slow response times. Here, a high responsivity self-powered p-n heterojunction UV PD based on TiO 2 NRs: CQDs/FTO and PEDOS/FTO is fabricated by a simple face-to-face assembly process. The pyroelectric effect of TiO 2 NRs is enhanced by sensitizing TiO 2 NRs with CQDs, which would reduce the bandgap value of TiO 2 NR, broaden the range of photoresponse, and reduce recombination of electron-hole. Furthermore, the pyro-phototronic effect of CQDs, the energy level matching from CQDs to PEDOS and the interaction between –OH in CQDs and ethylene oxide groups in PEDOS enhance the performance of the prepared UV PDs. The TiO 2 NRs: CQDs//PEDOS UV PDs achieve a high photo-responsivity and photo-detectivity of 150.95 mA/W and 3.73 × 1011 Jones at 0 bias (365 nm), respectively, which are better than those at wavelengths of 380 nm. We also found that the photocurrent induced via the pyro-phototronic effect increases with the light power intensity. This work points the way for photovoltaic and photo-induced pyro-phototronic effects to improve the performance of TiO 2 NRs-based UV PDs. [ABSTRACT FROM AUTHOR]

Based on high barrier performance, the combination of active/passive self-repairing and early corrosion monitoring functions becomes an ideal anti-corrosion strategy. Abundant surface polar functional groups of carbon quantum dots (CQDs) made of juice helped graphite carbon nitride(g-C 3 N 4) compatible with epoxy resin, and effectively improved the barrier property of CQDs@g-C 3 N 4 composites in coatings. In addition, the adsorption of CQDs on metal is the source of the active protective performance of the coating. The fluorescence characteristics of CQDs made it realizable to detect the micro-cracks in coatings. This work provides a meaningful strategy for the design of intelligent protective materials. [Display omitted] • A multifunctional coating was prepared via composite CQDs/g-C 3 N 4 and EP. • The modification of CQDs improved the interfacial compatibility between g-C 3 N 4 nanosheets and epoxy matrix. • CQDs/ g-C 3 N 4 endows EP coating with high shielding performance and self-healing ability. • The fluorescence characteristics of CQDs under ultraviolet light enable EP coatings to possess early corrosion monitoring function. [ABSTRACT FROM AUTHOR]

[Display omitted] • Using a non-toxic process to prepare biomass red and blue light emitting carbon quantum dots. • Red emitting carbon quantum dots exhibit excellent absorption performance for ultraviolet visible light. • The doping of carbon quantum dots significantly improves the band structure of C 3 N 4 /BiOBr. • The h+ and ·O 2 – of CQDs/C 3 N 4 /BiOBr are the main active species for photocatalytic degradation of RhB. The environmental crisis is an important factor that restricts human development. Biomass-derived carbon is an excellent material for the treatment of organic pollutants; however, realization of the energy band regulation of semiconductor photocatalysts remains challenging. Herein, we used green tea as a raw material to obtain different-colored carbon dots and hydrothermal carbon and introduced the C 3 N 4 /BiOBr Z-scheme heterostructure for enhancing electron transfer and band regulation. The experimental results show that the material exhibits good photocatalytic performance. 98.48% of rhodamine B (RhB) was degraded within 15 min by 20 wt% red light emitting carbon quantum dot doped C 3 N 4 /BiOBr, indicating that its performance is 4.07 times that of BiOBr. The electron spin resonance indicates that the composite material generates ·OH and ·O 2 − radicals and the reaction mechanisms of the catalyst and the intermediate from the RhB degradation. This study provides a new strategy for the development of biomass-derived carbon photocatalysis. [ABSTRACT FROM AUTHOR]

A facile and efficient hydrothermal method is utilized to assemble nitrogen-doped CQDs (NCQDs) onto graphene aerogel (GA) for reduction of toxic Cr (VI) in aqueous solution under visible light illumination. This work could extend the promising applications of CQDs as an efficient visible-light-responsive photosensitizer for water purification and beyond. • 3D nanostructured all-carbon composite has been fabricated. • Nitrogen-doped CQDs (NCQDs) exhibits enhenced visible light adsorption compared to undoped CQDs. • Graphene aerogel (GA) acts as a scaffold for the immobilisation of hydrophilic NCQDs. • NCQDs/GA shows synergetic effect for the reduction of Cr (VI) under visible light irradiation. Carbon quantum dots (CQDs) is a promising material for photosensitization applications but substantially suffers from the tedious product separation in solution and poor photosensitive efficiency in the visible light range. Herein, a facile and efficient hydrothermal method is utilized to assemble nitrogen-doped CQDs (NCQDs) onto graphene aerogel (GA) for reduction of toxic Cr (VI) in aqueous solution under visible light illumination. The photoactivity results suggest that GA skeleton endows NCQDs with a strongly enhanced photoactivity compared to that over blank NCQDs. Photoelectrochemical results demonstrate that the introduction of GA skeleton facilitates more efficient separation and transfer of photogenerated charge carriers under visible light irradiation. Moreover, as compared with N-free counterparts, the broadened light absorption of NCQD resulting from the ameliorated nanocrystallinity and the nitrogen dopant in graphitic structure play an important role in the reduction of Cr (VI) reaction under identical conditions. It is believed that this work could extend the promising applications of CQDs as an efficient visible-light-responsive photosensitizer for water purification and beyond. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • CuBi2O4 dumbbell-like architecture built from nanorods was synthesized. • The growth process of the dumbbell-like architecture was investigated. • CQDs and Ag2S nanoparticles were assembled on the surface of CuBi2O4 to form. CQDs/CuBi2O4 and Ag2S/CQDs/CuBi2O4 composites. • The Ag2S/CQDs/CuBi2O4 composite exhibits the highest photocatalytic activity. • The enhanced photocatalytic mechanism of the composite was investigated. Abstract CuBi 2 O 4 dumbbell-like architecture built from nanorods was synthesized by a simple coprecipitation route. The growth process of the dumbbell-like architecture was investigated by varying the reaction duration time. Carbon quantum dots (CQDs) and Ag 2 S nanoparticles were assembled on the surface of the CuBi 2 O 4 dumbbell-like architecture to produce CQDs/CuBi 2 O 4 and Ag 2 S/CQDs/CuBi 2 O 4 composites. Compared to bare CuBi 2 O 4 , the composites, particularly Ag 2 S/CQDs/CuBi 2 O 4 , manifest an increased visible light absorption, increased photocurrent density and decreased charge-transfer resistance. Using simulated sunlight as the light source and rhodamine B (RhB) dye as the target organic pollutant, the photocatalytic activity of the samples was investigated. It is demonstrated that the Ag 2 S/CQDs/CuBi 2 O 4 composite exhibits the highest photocatalytic activity toward the RhB degradation. This is due to the highly efficient separation of electron/hole pairs and increased visible light absorption of the Ag 2 S/CQDs/CuBi 2 O 4 composite. [ABSTRACT FROM AUTHOR]

• The multi-dimensional CQDs/CdIn 2 S 4 /N-rGO composites were successfully prepared. • The TOC remove rate of 2,4-DCP mineralized by CQDs/CdIn 2 S 4 /N-rGO photocatalyst was 65.52%. • The π-conjugated system, heterojunction, synergistic effect better photodegradation of 2,4-DCP. • A possible mechanism for enhancing photocatalytic performance was proposed. The muti-dimensional carbon quantum dots (CQDs) modifying sphere-flower CdIn 2 S 4 on nitrogen doping on reduced graphene oxide (N-rGO) photocatalyst is fabricated through the simple hydrothermal method and solvothermal method. CQDs/CdIn 2 S 4 /N-rGO composites show good photocatalytic degradation for 80% 50 mg/L 2,4-dichlorophenol under visible light for 6 h, which could be ascribable to the good conductive property and defects of N-rGO sheet (two dimension) and the heterojunction constructed between CQDs (zero dimension) and sphere-flower CdIn 2 S 4 (three dimension), and synergism among them. These are evidenced by the photoluminescence spectra, photocurrent intensity, high-resolution transmission electron microscopy and Raman spectra. Besides, the results of ESR show that ·O 2 − and ·OH radicals both are generated under visible light, ·OH the main one further confirmed by free radicals trapping experiments. This work will give some inspirations for constructing multi-dimensional semiconductors with excellent photocatalytic performance. [ABSTRACT FROM AUTHOR]

Preparation of earth-abundant and noble-metal-free transition metal complexes serving as photocatalytic hydrogen evolution co-catalysts is of great challenge and significance. Here, ternary photocatalysts Co(dcbpy) 2 (NCS) 2 /CQDs/CN by amide bonds coupling Co(dcbpy) 2 (NCS) 2 [dcbpy = (4, 4′-dicarboxy-2, 2′-bipyridine)] with amino-functionalized carbon quantum dots (CQDs) or graphitic carbon nitride nanosheets (CN) were developed for efficient solar-to-hydrogen conversion. The amide bonds accelerate the combination of Co(dcbpy) 2 (NCS) 2 and CQDs/CN and improve the dispersion of Co(dcbpy) 2 (NCS) 2 on CN framework, thus leading to enhanced migration of charge carriers and absorption of visible light. In addition, the optimum photocatalytic hydrogen evolution activity of Co(dcbpy) 2 (NCS) 2 /CQDs/CN catalyst reaches 295.9 μmol h−1 g−1 with excellent stability after four cycling tests under visible light irradiation. The hydrogen evolution activity of 3Co(dcbpy) 2 (NCS) 2 /CQDs/CN catalyst reaches 75.02 μmol h−1 g−1 under monochromatic light irradiation (λ = 450 nm) and the apparent quantum efficiency reaches 14.11%, whereas pure CN is inactive under the same condition. The amide bond between cobalt-based complex and CN plays an important role for excellent photocatalytic performance. More importantly, the composite catalysts give a new insight for designing noble-metal-free co-catalysts with excellent photocatalytic activity and high stability towards solar-to-hydrogen conversion. Ternary photocatalysts Co(dcbpy) 2 (NCS) 2 /CQDs/CN were developed by amide bonds coupling Co(dcbpy) 2 (NCS) 2 [dcbpy = (4, 4′-dicarboxy-2, 2′-bipyridine)] with amino-functionalized carbon quantum dots (CQDs) or graphitic carbon nitride nanosheets (CN) for efficient solar-to-hydrogen conversion. This study demonstrates a simple way to design noble-metal-free co-catalysts with excellent photocatalytic activity and high stability towards solar-to-hydrogen conversion. Image 1 [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ternary Co/CQDs/ZnIn 2 S 4 were obtained by impregnating CQDs/ZnIn 2 S 4 with Co(dmgH) 2 PyCl. • Co/CQDs/ZnIn 2 S 4 show superior photocatalytic activity for hydrogen evolution. • CQDs acts as a mediator to promote electrons transfer to Co(dmgH) 2 PyCl. Abstract CQDs/ZnIn 2 S 4 nanocomposites (CQDs stands for carbon quantum dot) prepared by a microwave method in the presence of performed CQDs were impregnated with Co(dmgH) 2 PyCl (dmgH = dimethylglyoxime, Py = pyridine) to form ternary Co(dmgH) 2 PyCl/CQDs/ZnIn 2 S 4 nanocomposites (Co/CQDs/ZnIn 2 S 4). The photocatalytic performance for hydrogen evolution in the presence of TEOA as a sacrificial agent over the as-obtained Co/CQDs/ZnIn 2 S 4 under visible light was investigated. It was found that ternary Co/CQDs/ZnIn 2 S 4 show significantly superior photocatalytic activity for hydrogen evolution than both Co(dmgH) 2 PyCl/ZnIn 2 S 4 and CQDs/ZnIn 2 S 4. An optimum activity was realized over Co/CQDs/ZnIn 2 S 4 with the loading amount of 5.0 wt% CQDs and 1.0 wt% Co(dmgH) 2 PyCl, in which 703.9 μmol of hydrogen was evolved in 8 h. The superior photocatalytic activity for hydrogen evolution over ternary Co/CQDs/ZnIn 2 S 4 can be ascribed to the synergistic effect played by CQDs and Co(dmgH) 2 PyCl, in which CQDs acts as a mediator to promote the transfer of the photogenerated electrons to Co(dmgH) 2 PyCl, the hydrogen evolution cocatalyst. This work provides some guidance for the design of noble metal free photocatalysts for hydrogen generation and highlights the potential of using CQDs to promote the charge transfer in semiconductor-based photocatalysis. [ABSTRACT FROM AUTHOR]

Abstract Biomass carbon quantum dots (CQDs) were widely used in bioimaging and WO 2.72 has great potential in cancer therapy. The biomass CQDs were prepared by mixed acid oxidation method with biomass materials such as pods, tobacco leaves and cysteine as carbon sources. Properties of biomass carbon quantum dots were characterized, including micromorphology, the functional group composition, photoluminescence properties and fluorescence labeling ability in HepG2 cells. And the cytotoxicity of CQDs in HepG2 and MCF-7 cells was tested. In this paper, in situ loading of biomass CQDs on one dimensional long rod like WO 2.72 (C-WO 2.72) was synthesized by solvothermal method. Properties of C-WO 2.72 were characterized, including the phase composition, the functional group composition, micromorphology and absorbability. [ABSTRACT FROM AUTHOR]

Semiconductor photocatalysis is considered as an effective technology to ease the global energy shortage, designing efficient photocatalysts with enhanced light absorption, carrier separation and surface reaction is still one of the main strategies to solve its practical application. In this paper, the structure of the synthesized material was controlled by regular polystyrene (PS) colloidal spheres as templates, and the 3DOM SrTiO 3 -TiO 2 composite modified by carbon quantum dots (CQDs) with three-dimensional ordered macroporous structure was prepared. In this composite, CQDs with up-conversion characteristics are used as photosensitizers to expand light absorption. The combination of SrTiO 3 and TiO 2 enhances the separation efficiency of charges, and the three-dimensional ordered macropore structure reduces the resistance of substances entering the catalyst, further improving the catalytic performance of the material. Under the irradiation of xenon lamp, the hydrogen evolution of the prepared CQDs/3DOM SrTiO 3 -TiO 2 composite reached 578.95 μmol·g−1 after 8 h of photolysis, which is 14.5 times that of the monomer TiO 2. In addition, with Rhodamine B (RhB) as the model molecule, the photocatalytic degradation activity of CQDs/3DOM SrTiO 3 -TiO 2 was significantly better than that of other contrast systems under the experimental conditions of multimode photocatalytic degradation, showing enhanced photocatalytic degradation and hydrogen production from water photolysis. This study provides a feasible method for preparing three-dimensional ordered macroporous materials with excellent photocatalytic properties. [Display omitted] • Using polystyrene colloidal spheres as templates, the 3DOM SrTiO 3- TiO 2 composites modified by CQDs were prepared. • CQDs with up-conversion characteristics were used as photosensitizers to expand light absorption of as-composites. • CQDs act as the electron transfer medium to accelerate the electron transfer rate. • The combination of SrTiO 3 and TiO 2 enhances the separation efficiency of charges. • CQDs/3DOM SrTiO 3- TiO 2 shows excellent photocatalytic properties under multiple conditions. [ABSTRACT FROM AUTHOR]

Numerous researches were interestingly considered with investigation of unique strategies for industrialization of efficacious textiles to find wide-scaled applicability in different purposes. The demonstrated approach represents unique strategy for manufacturing of fluorescent/UV-resistant/microbicide cotton via exploitation of silver nanoparticles (AgNPs), carbon quantum dots (CQDs) and silver nanoparticles-doped carbon quantum dots (AgNPs-CQDs) to be applicable as efficacious textiles. Whereas, both CQDs and AgNPs were formerly clustered from alginate biopolymer. Topographical features and particle size of AgNPs (7.5 ± 2.6 nm), CQDs (4.9 ± 1.7 nm) & AgNPs-CQDs (4.0 ± 1.4 nm) were investigated via microscopic images and Zetasizer data. Spectral mapping data for the photoluminescent emission showed that, AgNPs, CQDs & AgNPs-CQDs were exhibited with two intense peaks at 370 nm & 490 nm. Cotton fabrics were sequentially treated with CQDs, Ag-CQDs & AgNPs-CQDs to prepare CQDs@Cotton, Ag-CQDs@Cotton and AgNPs-CQDs@Cotton, respectively. Thermal stability, colorimetric properties/color strength, UV-resistance and antimicrobial potentiality were studied for all the prepared samples. AgNPs-CQDs@Cotton exhibited excellent UV-resistance (UPF, 43.4) and antimicrobial activity, whereas the diameter of inhibition zone was estimated for its affinity against S. aureus , E. coli and C. albicans , to be 14 mm, 18 mm and 16 mm, respectively. [Display omitted] • Fluorescent/UV-resistant/microbicidal effecieous textile via AgNPs doped-CQDs. • CQDs and AgNPs were formerly clustered from alginate biopolymer. • AgNPs, CQDs & AgNPs-CQDs exhibited size of 7.5, 4.9 & 4.0 nm, respectively. • AgNPs-CQDs@cotton was obviously observed with the highest thermal stability. • AgNPs-CQDs@Cotton exhibited excellent UV-resistance and antimicrobial performance. [ABSTRACT FROM AUTHOR]

The poor stability of carbon nanofluids limits their application in solar desalination process, especially when nanoparticles need to contact with saline water directly. Herein, this study proposes a mild manufacturing route to prepare the highly stable carbon quantum dots (CQDs) nanofluids by microwave method coupling a simple dilution. The systematic stability evaluation was conducted and the results showed almost all of CQDs nanofluids could keep stable in saline water with a wide NaCl concentration range (from 0 to 50 g/L), different co-existing salt ions and organic matters. The high thermal stability of CQDs nanofluids also were proved and the variation of Turbiscan stability index (TSI) value was below 0.24 after five heating cycles. The optical properties were evaluated and nearly 100 % incoming solar energy was captured by 10 vol% CQDs nanofluids. The above results indicate the application potential of CQDs nanofluids in solar desalination process. Moreover, the performance of solar still with CQDs nanofluids was compared with the conventional solar still. The results show that the cumulative water productions are 521 mL in the conventional solar still and 823 mL in the solar still with CQDs nanofluids of an enhancement in the water productivity of 57.9 %. The average energy efficiency of solar still with or without CQDs nanofluids are 34.23 % and 21.52 %, respectively. In addition, the economic analysis was conducted and the results show water production cost is 0.013–0.015 $/L for solar still with CQDs nanofluids. [Display omitted] • 0.9 g/L CQDs generate from PEG-200 within 30 min microwave treatment. • CQDs nanofluids can keep stable with NaCl concentration from 0 to 5 g/L. • Water yield and energy efficiency are enhanced 57.9 % and 12.71 % in the solar still. • The water production cost is 0.013 to 0.015 $/L for solar still with nanofluids. [ABSTRACT FROM AUTHOR]

In this work, a highly selective and sensitive chemiluminescence (CL) biosensor was prepared for adenosine (AD) detection based on carbon quantum dots (CQDs) catalyzing the CL system of luminol-H 2 O 2 under alkaline environment and CQDs was released from the surface of AD aptamers functionalized graphene @ magnetic β-cyclodextrin polymers (GO@Fe 3 O 4 @β-CD@A-Apt). Firstly, GO@Fe 3 O 4 @β-CD and CQDs were prepared and characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), UV–Vis absorption spectra (UV), fluorescence spectra (FL), fourier transform infrared (FTIR) and X-ray powder diffraction (XRD). For GO@Fe 3 O 4 @β-CD, Fe 3 O 4 was easy to separate, GO had good biocompatibility and large specific surface area, and β-CD further increased the specific surface area of the adenosine polymers (A-Apt) to provided larger binding sites to A-Apt. Then, A-Apt was modified on the surface of GO@Fe 3 O 4 @β-CD while CQDs was modified by ssDNA (a single stranded DNA partially complementary to A-Apt). The immobilization property (GO@Fe 3 O 4 @β-CD to A-Apt) and the adsorption property (GO@Fe 3 O 4 @β-CD@A-Apt to CQDs-ssDNA) were sequentially researched. The base-supported chain-like polymers – GO@Fe 3 O 4 @β-CD@A-Apt/CQDs-ssDNA was successfully obtained. When AD existed, CQDs-ssDNA was released from the surface of GO@Fe 3 O 4 @β-CD@A-Apt and catalyzed CL. After that, under optimized CL conditions, AD could be measured with the linear concentration range of 5.0 × 10 −13 –5.0 × 10 −9 mol/L and the detection limit of 2.1 × 10 −13 mol/L (3δ) while the relative standard deviation (RSD) was 1.4%. Finally, the GO@Fe 3 O 4 @β-CD@A-Apt/CQDs-ssDNA-CL biosensor was used for the determination of AD in urine samples and recoveries ranged from 98.6% to 101.0%. Those satisfactory results illustrated the proposed CL biosensor could achieve highly selective, sensitive and reliable detection of AD and revealed potential application for AD detection in monitoring and diagnosis of human cancers. [ABSTRACT FROM AUTHOR]

Although the salt-adjusted properties of nanomaterials have been extensively used for colorimetric assays of all kinds of analytes, their applications in the design of fluorescence sensor are very limited. Herein, a novel fluorescence aptasensor was developed for the sensitive determination of Bisphenol S (BPS) by the salt-adjusted fluorescence resonance energy transfer (FRET) between the zero-dimensional emitter (CQDs) and the two-dimensional absorber (MoS 2 nanosheets) and the roles of specific discrimination and protective effect of anti-BPS aptamer to layered MoS 2 . It is shown that layered MoS 2 can serve as a good fluorescent quencher towards carbon dots with decent quenching efficiency. Importantly, the established fluorescent method achieved satisfactory results for the determination of BPS with a good linear correlation from 0.05 μM to 2 μM and a detection limit of 2 nM. It is expected that this method may offer a new direction for the application of the phenomenon of salt-assisted aggregation of nanomaterials in designing high-performance fluorescent biosensors. [ABSTRACT FROM AUTHOR]

In this study, TiO 2 /CQDs(TC), TiO 2 /BiOI(TB), TiO 2 /BiOI/CQDs(TBC) were prepared via a step-by-step method. Photocatalytic properties of the samples were carried out under visible-light irradiation using methyl orange (MO) as the target molecular. Among the samples, TBC showed the best photocatalytic performance, and the photocatalytic efficiency of TBC was more than 2 times higher than that of TiO 2 , TC and TB samples, respectively. The reasons for the improved photocatalytic performance were discussed in this paper. [ABSTRACT FROM AUTHOR]

The 3D porous CQDs/LDHs have been synthesized using CQDs as structure-directing agent to adsorb boron(III) from aqueous solution. Characteristic results showed that the prepared CQDs/LDHs have high adsorption capacity and selectivity. FTIR and XPS spectra revealed that CQDs/LDHs possessed more oxygen-containing groups than LDHs. BET data revealed that CQDs/LDHs had a specific surface area of 186 m 2 /g, which is twice larger than LDHs of 91.6 m 2 /g. Effects of the temperature, pH and boron(III) concentration on adsorption performance of boron(III) were investigated. The results showed that the maximum adsorption capacity of 19.5 mg/g on CQDs/LDHs was obtained when the initial boron(III) concentration is 20 mg/L at pH 8.5. In the competitive adsorption system, the removal rate of CQDs/LDHs toward boron(III) can reach to 89.7%, which is three times bigger than raw LDHs. Adsorption isotherm and kinetics studies revealed that boron(III) adsorption process was well-described by Langmuir isotherm and pseudo-second-order kinetic model, respectively. Adsorption and characterization data proved that the adsorption mechanism of boron(III) is a complex process, including anion exchange and oxygen-containing group adsorption. This work not only gives a new way to synthesize 3D porous material but also provides a potential material to selectively adsorp boron(III). [ABSTRACT FROM AUTHOR]

The residue obtained from the pyrolysis of waste polyolefins, has been used for preparation of highly green-visual fluorescent carbon quantum dots (CQDs) by a simple one step hydrothermal approach consisting of ultrasonic-assisted chemical oxidation. These CQDs were characterized by UV–vis absorption spectroscopy, fluorescence spectroscopy, TEM, XRD, and FTIR. The CQDs possessed high stability in aqueous solution and exhibited strong fluorescence with quantum yield of 4.84%. The use of these CQDs as a fluorescent sensor for Cu 2+ ions detection has been explored. The synthesized CQDs have excellent selectivity and sensitivity towards Cu 2+ ions with a limit of detection (LOD) 6.33 nM and linear detection range of 1–8.0 μM. These CQDs have also shown their utility for analysis of real water samples and have the potential to use for triple negative breast cancer cells (MDA-MB 468 cells) imaging. [ABSTRACT FROM AUTHOR]

Schematic photocatalytic mechanism for the LFC 0.5 /G-CQDs composites. [Display omitted] • Novel LFC 0.5 /CQDs catalyst was prepared via a facile, cheap and green method. • LFC 0.5 /G-CQDs degradation kinetics was 14 times higher than that of pure LFC 0.5. • A Z-scheme heterojunction mechanism for LFC 0.5 /G-CQDs was deduced. • LFC 0.5 /G-CQDs composite owns a satisfied life span and potential application value. • The luminescence position of CQDs affects the performance of the composite. The environmentally friendly semiconductor photocatalyst has tremendous potential for resolving wastewater pollution issues. This study describes the successful fabrication of a novel (LaFe 0.5 Cu 0.5 O 3) LFC 0.5 /CQDs nanocomposite using a simple cryogenic-calcination method. The LFC 0.5 /G-CQDs composite displayed the greatest light absorption range and photogenerated carrier separation ability based on their various optical characteristics and electron transfer capabilities. Moreover, its quinoline degradation kinetics were 14 times greater than those of pure LFC 0.5. According to the findings of a thorough investigation, this excellent photocatalytic performance may be ascribed to the synergistic effects of the up-converted fluorescent properties of G-CQDs, tuned band structure, and effective charge separation caused by the formation of heterojunction. Based on the findings of the experimental quenching, it was clear that the LFC 0.5 /G-CQDs photocatalytic process was dominated by the radicals ∙OH and ∙O 2 −. A potential Z-scheme heterojunction mechanism for quinoline degradation by LFC 0.5 /G-CQDs was elucidated using band structure analysis and EPR data. In addition, the composite photocatalyst LFC 0.5 /G-CQDs demonstrated excellent reusability over five cycles. In addition to developing highly efficient visible-light-driven photocatalysts for degrading Quinoline, this study suggests that implementing carbon quantum dots at the center of the main catalyst's luminescence will maximize light utilization and enhance photocatalytic performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon quantum dots (CQDs) were synthesized from Sideritis Vuralii by green method. • CQDs were characterized by fluorescence and UV–Vis spectroscopies and XPS. • The Cyclic Voltammetry (CV) analyses show the CQDs electrolytes show supercapacitor electrolyte feature. Quantum dots have good optical and electrical behaviors and can be employed in solar cells, displays and supercapacitors. When new studies in nanoparticle as well as synthesis of quantum dots are examined, it can be seen that the interest in the green synthesis approach has increased. The green synthesis approach is so prominent due to an environmentally friendly method and does not contain toxic chemicals at the experimental stage. In this study, we used Sideritis vuralii (S. vuralii) , which is endemic in Turkey, as a source of the green synthesis approach. We synthesized carbon quantum dot (CQDs) particles with the hydrothermal method from S. vuralii plant. We performed UV–Vis spectra, fluorescence spectra, XPS and DLS analyzes for the characterization of the CQDs. According to the size and characteristics results, the CQDs were successfully synthesized from the S. vuralii plant. Furthermore, we employed CQDs as electrode for capacitor applications, and cyclic voltammetry (CV) measurements were performed. The CV measurements indicated that CQDs electrodes have rechargeable symmetrical capacitor behaviors with 10.42 F/g charge, 8.26 F/g discharge capacitances. The green synthesized CQDs can be improved for supercapacitor applications. [ABSTRACT FROM AUTHOR]