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Shape-dependant photocatalytic and antimicrobial activity of ZnO nanostructures when conjugated to graphene quantum dots
摘要： To reduce the bandgap and e-/h+ pairs recombination, zinc oxide nanoflakes (ZnO-NFs) and zinc oxide nanorods (ZnO-NRs) were covalently linked to graphene oxide quantum dots (GQDs). Photocatalytic and antimicrobial activity of ZnO nanohybrids (ZnO-NFs@GQDs and ZnO-NRs@GQDs) were investigated. The formation of the distinct ZnO nanoflakes and ZnO nanorods shaped nanoparticles were evidenced by SEM. The bandgap decreased from 2.98 to 2.61 eV and 3.00 to 2.79 eV for ZnO-NFs@GQDs and ZnO-NRs@GQDs, respectively. Photoluminescence (PL) data showed a similar trend where a larger decrease was obtained for ZnO-NFs@GQDs. Photolysis ruled out adsorption mechanism for the removal of dye. Optical data and PL measurements supported photocatalytic findings that ZnO-NFs@GQDs performed better (80%) than ZnO-NRs@GQDs (18%). ZnO-NRs@GQDs however, showed greater bacterial inhibition when tested against E. coli, P. aeruginosa, B. cereus and S. aureus. The antimicrobial efficiency followed the order: ZnO-NFs < ZnO-NFs@GQDs < ZnO-NRs < ZnO-NRs@GQDs with greater efficiency being against S. aureus. Liquid photocatalysts zinc nanoparticles can thus be used to remove dyes and inhibit bacterial growth in aqueous solution.
关键词： Zinc oxide nanorods,zinc oxide nanoflakes,antimicrobial activity,photocatalysis,graphene quantum dots
更新于2025-09-23 15:19:57
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Facet-energy inspired metal oxide extended hexapod decorated with graphene quantum dots: Sensitive detection of bisphenol A in live cells
摘要： The development of crystal-facet metal oxide heterostructures has been of great interest owing to their rational design and multi-functioning properties at the nanoscale level. Herein, we report a facile solution-based method for the synthesis of single-crystal Cu2O nanostructures (i.e. Cu2O-CuO) as a core. The graphene quantum dots (GQDs) with varying concentrations are harvested on the surface of Cu2O extended hexapods (EHPs) in ethanol solution at room temperature via self-assembly, where copper acts as a sacrificial model and stabilizer as well. The Cu2O crystals displayed a good sensing activity toward BPA oxidation owing to high energy facets, dangling bonds and great proportion of surface copper atoms. The structural, morphological, chemical and vibrational investigations were attained in detail, presenting high crystallinity of the hybrid nanocomposite and Cu2O-CuO heterojunction positions along with the growth of GQDs on the core of Cu2O-CuO crystal. The electrochemical sensing performance of as-fabricated Cu2O-CuO@GQDs EHPs has been monitored for the determination of bisphenol A (BPA) as an early diagnostic marker and environmental contaminant. The synergy effect of boosted surface area, exposed Cu {111} crystallographic planes and mixed copper valences enhance redox reaction kinetics by increasing the electron shuttling rate at the electrode-analyte junction. Benefitted from the improved electrocatalytic activity for BPA oxidation, the electrochemical sensor displayed the lowest limit of detection (≤1 nM), good chemical stability and broad linear range (2 nM - 11 mM), and high sensitivity (636 μA mM-1 cm-2). The Cu2O-CuO@GQDs EHPs based sensing platform has been applied for BPA detection in water and human serum samples. We have also constructed up a pioneering electrochemical sensing podium for BPA detection in live cells which might be used as a marker in early disease diagnosis.
关键词： electrochemical sensor,bisphenol A,live cells,graphene quantum dots,crystal-facet metal oxide heterostructures
更新于2025-09-23 15:19:57
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Carbon Nanomaterials for Agri-Food and Environmental Applications || Graphene quantum dot-based nanostructures for water treatment
摘要： Water pollution by organic, inorganic, and microbial species presents a threat to the water supply as well as food safety and security. Graphene quantum dot-derived nanostructures have emerged as potential solutions toward water pollution mitigation. Such materials have been successfully prepared and evaluated for the catalytic removal of organic pollutants such as dyes and emerging pollutants, the adsorption of pollutants, filtration, and disinfection. Incorporation of GQDs in various nanocomposites resulted in the modification of the composite properties and improved the removal efficiencies of different pollutants. Careful control and optimization of the amounts of GQDs incorporated are necessary to ensure a positive influence in the pollutant-removal efficiencies of the different nanocomposites. Despite the promising developments around GQD-based nanostructures, more work still remains in order to ensure the design and utilization of such materials in large-scale applications. Nonetheless, GQD-derived nanostructures have potential as pollution remediation tools, owing to the nontoxicity, biodegradable, and abundant functional groups. However, there is a need to develop optimized synthesis conditions that will yield GQDs that are uniform in terms of size and surface functionalities and also develop synthesis routes that will ensure proper distribution of the GQDs within the nanocomposite matrix. This could contribute to consistency in terms of the reported performances of various GQD-derived nanostructures in water pollution abatement.
关键词： membrane filtration,photocatalysis,Graphene quantum dots,water treatment,adsorption
更新于2025-09-23 15:19:57
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Bio-template assisted hierarchical ZnO superstructures coupled with graphene quantum dots for enhanced water oxidation kinetics
摘要： Due to anisotropic growth behavior and tunable electrical properties, ZnO nanostructures having dimensions such as 0-D, 1-D, 2-D and 3-D are actively studied for their optoelectronic properties. However, ZnO based photoanodes suffer from unfavorable recombination of electron hole pair, which hinders its use in photoelectrochemical (PEC) water oxidation. Herein, we demonstrate a strategy to enhance the PEC performance using bio-template assisted in-situ grown hierarchical ZnO superstructures directly over fluorine-doped tin oxide (FTO) modified by graphene quantum dots (GQDs). GQDs decorated hierarchical ZnO superstructures displayed a significant increment of ~77% in photocurrent density value compared to pristine ZnO with an impressive carrier density of 3.19 × 1020 cm?3, which is ~1.8 orders of magnitude higher than that of pristine ZnO. It is observed that GQDs acts as an efficient hole extractor, which improves the carrier separation on ZnO surface and reduces the hole trapping probability.
关键词： Hole extracting agent,Polygalacturonic acid,Hierarchical ZnO superstructures,Photoelectrochemical water oxidation,Graphene quantum dots
更新于2025-09-23 15:19:57
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Boosting multiple interfaces by co-doped graphene quantum dots for high efficiency and durability perovskite solar cells
摘要： Organic-inorganic hybrid perovskite solar cells (PSCs), as the most rapidly developing next-generation thin-film photovoltaic technology, have attracted extensive research interests, yet their efficiency, scalability, and durability remain challenging. IH.(cid:8)2O3 could be served as electron transporting layer (ETL) of planar PSCs, which exhibited a much higher humidity and UV light-stability compared to TiO2-based planar PSCs. However, the photovoltaic conversion efficiency (PCE) of Fe2O3-based device was still below 15% because of poor interface contact between IH Fe2O3 and perovskite, and poor crystal quality of perovskite. In this work, we have engineered the interfaces throughout the entire solar cell via incorporating N, S co-doped graphene quantum dots (NSGQDs). The NSGQDs played remarkably multifunctional roles: i) facilitated the perovskite crystal growth; ii) eased charge extraction at both anode and cathode interfaces; iii) induced the defect passivation and suppressed the charge recombination. When assembled with a IH.(cid:8)2O3 ETL, the planar PSCs exhibited a significantly increased efficiency from 14% to 19.2%, with concomitant reductions in hysteresis, which created a new record of PCE for Fe2O3-based PSCs to date. In addition, PSCs with the entire device interfacial engineering showed an obviously improved durability, including prominent humidity, UV light and thermal-stabilities. Our interfacial engineering methodology via graphene quantum dots represents a versatile and effective way for building high efficiency as well as durability PSCs.
关键词： stability,Perovskite solar cells,interface engineering,PCE,graphene quantum dots,Fe2O3
更新于2025-09-23 15:19:57
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Bridge between Temperature and Light: Bottom-Up Synthetic Route to Structure-Defined Graphene Quantum Dots as a Temperature Probe In Vitro and in Cells
摘要： Owing to their unique superiorities in chemical and photoluminescence (PL) stability, low toxicity, biocompatibility, and easy functionalization, graphene quantum dots (GQDs) were widely used in cell imaging, probes, and sensors. However, further development and deeper research of GQDs were restricted by their imprecise and complex structure and accompanying controversial PL mechanism. In this work, two kinds of structure defined water-soluble GQDs, with different oxidation degree, were synthesized from molecules by using bottom-up syntheses methods. After studied by a serial of characterizations, their optical properties, functional groups, molecular weight, and structural information were obtained. The optical properties of GQDs could be optimized by controlling their oxidation degree. PL mechanism of GQDs was investigated by comparing their structure and properties. Furthermore, robust, stable, and precise temperature probes were designed by using the GQDs, which exhibited an excellent wide responding range, which covered the whole physiology temperature range, from 0 ℃ to 60 ℃ in water. Moreover, the GQDs were successfully applied as temperature responsive fluorescence probe in Hela cell line. These works put forward a solid foundation for the applications of biological thermo probes and selectively temperature detectors in vitro cellular and in vivo.
关键词： structure controllable,living cell imaging,temperature probe,bottom-up synthesis,mechanism,graphene quantum dots
更新于2025-09-23 15:19:57
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TiO2 nanotubes modified with polydopamine and graphene quantum dots as a photochemical biosensor for the ultrasensitive detection of glucose
摘要： Rapid and sensitive detection of glucose concentrations is very important for human health. Herein, an ultrasensitive photoelectrochemical dual-electron-acceptor biosensor was constructed by modifying the TiO2 nanotubes (NTs) with polydopamine (PDA) and amino-functionalized graphene quantum dots (N-GQDs)/GOx. PDA is grown on the top of the TiO2 NTs by the electropolymerization, and N-GQDs are loaded into the inner of the TiO2 NTs by a microwave-assisted method. The TiO2 NTs/PDA/N-GQD dual-electron-acceptor biosensor exhibited a highly enhanced photoelectric response, excellent electron–hole separation efficiency, low detection limit (0.015 mM), wide linear range (0–11 mM) and ultrahigh sensitivity (13.6 lA mM-1 cm-2). The prepared biosensor reflected high selectivity and excellent stability. This work also provides new insights into other optoelectronic biosensors.
关键词： photochemical biosensor,polydopamine,graphene quantum dots,TiO2 nanotubes,glucose detection
更新于2025-09-23 15:19:57
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Sulfur doped graphene quantum dots as a potential sensitive fluorescent probe for the detection of quercetin
摘要： In this work, a novel, selective and sensitive fluorescent probe (sulfur doped graphene quantum dots, SGQDs) was designed for real-time detection of quercetin in red wine samples. SGQDs were synthesized by pyrolyzing citric acid (CA) and 3-Mercaptopropionic acid (MPA) and characterized through advanced techniques. It was observed that fluorescence intensity of SGQDs could be substantially quenched by the addition of quercetin through inner filter effect (IFE) mechanism. Additionally, a visual color change (colorless to light yellow) was also noticed after addition of quercetin into a solution of SGQDs. The change in SGQDs fluorescence intensity with varying quercetin content revealed good linearity in the 0-50.0 μM range with regression coefficient of 0.9943 and a lowest detection limit of 0.006 μg/mL. To authenticate the real-time application of SGQDs as a potential fluorescent probe, red wine samples having different quercetin concentrations were used for quantitative analysis, after the optimization of several analytical parameters.
关键词： Sulfur doped graphene quantum dots,inner filter effect,pharmaceutical assay,fluorescent probe,quenching,quercetin
更新于2025-09-23 15:19:57
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CuIn-ethylxanthate a a??versatile precursora?? for photosensitization of graphene-quantum dots and nanocatalyzed synthesis of imidazopyridines with ideal green chemistry metrics
摘要： Recently, the development of hybrid nano catalyst involving earth abundant transition metals for photosensitization and multi-component reaction in industry and academia has been a matter of intense study. Such hybridized catalytic systems minimize the production cost and acts as a bridged system by diversifying the application in different areas. In the present study copper indium ethylxanthate was used as a versatile precursor for synthesis of colloidal chalcopyrite phase copper indium sulphide (CC-CIS NPs) in photosensitization of graphene quantum dots and reusable powdered wurzite phased copper indium sulphide nanoparticles (PW-CIS500 NPs) for selective and efficient single pot sustainable synthesis of substituted imidazopyridines via A3 coupling strategy of an aldehyde, amine and alkyne. The material was characterized by various spectroscopic techniques viz HR-TEM, PXRD, FESEM, elemental mapping studies, UV visible spectroscopy, photoluminescence, XPS, BET and ICP-OES/MS etc. Quenching of photoluminescence intensity of colloidal CuInS2 on anchoring the graphene quantum dots (GQDs) was confirmed by photosensitization of GQDs via efficient charge transfer in CIS-GQD interface. On the other hand, the PW-CIS500 NCs catalyzed A3 coupling strategy demonstrates the high catalytic efficiency for A3 coupling reaction giving substituted imidazopyridines without losing its activity and could be recycled with a total turnover number of > 210, good E-factor of 0.13 and high RME of 88%.
关键词： multicomponent reactions,heterogenous catalysis,copper indium sulphide,copper indium ethylxanthate,imidazopyridines,graphene quantum dots,charge transfer
更新于2025-09-23 15:19:57
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Coumarin-Modified Graphene Quantum Dots as a Sensing Platform for Multicomponent Detection and Its Applications in Fruits and Living Cells
摘要： In this work, coumarin derivatives (C) are used to enhance the ?uorescence of graphene quantum dots (GQDs) by covalently linking the carboxyl groups on the edge of the GQD sheet. The as-synthesized coumarin-modi?ed graphene quantum dots (C-GQDs) have a uniform particle size with an average diameter of 3.6 nm. Simultaneously, the C-GQDs have strong ?uorescence emission, excellent photostability, and high ?uorescence quantum yield. C-GQDs and CN? can form a C-GQDs+CN? system due to deprotonation and/or intermolecular interactions. The introduced hydroquinone (HQ) is oxidized to benzoquinone (BQ), and the interaction between BQ and the C-GQDs+CN? system could lead to ?uorescence enhancement of C-GQDs. Meanwhile, the redox reaction between BQ and ascorbic acid (AA) can be used for quantitative detection of AA with CN? and HQ being used as substrates. Based on the above mechanism, C-GQDs are developed as a multicomponent detection and sensing platform, and the detection limits for CN?, HQ, and AA were 4.7, 2.2, and 2.2 nM, respectively. More importantly, satisfactory results were obtained when the platform was used to detect CN?, HQ, and AA in living cells and fresh fruits.
关键词： multicomponent detection,CN?,fluorescent probe,HQ,coumarin-modi?ed graphene quantum dots,AA
更新于2025-09-23 15:19:57