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Incorporating graphene quantum dots to enhance the photoactivity of CdSe-sensitized TiO2 nanorods for solar hydrogen production
摘要： This work demonstrated that the incorporation of graphene quantum dots (GQDs) can greatly improve the photoelectrochemical (PEC) efficiency of CdSe-sensitized TiO2 nanorods (TiO2/CdSe), a TiO2-based visible light-responsive photoelectrode paradigm, for solar hydrogen production. For TiO2/CdSe, the accumulated holes at CdSe may induce photocorrosive oxidation to decompose CdSe, deteriorating the long-term stability of photoelectrode and degrading the PEC performance. With the introduction of GQDs, the delocalized holes can further transfer from CdSe to the GQDs, which eases the hole accumulation at the CdSe sites, thus retarding photocorrosion. Compared to the binary TiO2/CdSe photoanode, the ternary TiO2/CdSe/GQDs photoanode displays higher photocurrent and better photostability toward PEC hydrogen production. This superiority can be attributed to vectorial charge transfer and enhanced reaction kinetics provided by the introduction of GQDs. The findings from this work highlight the importance of the introduction of GQDs as a potential solution to the photocorrosion issue of chalcogenide-sensitized semiconductor photoelectrodes.
关键词： photocorrosion,photoelectrochemical efficiency,solar hydrogen production,CdSe-sensitized TiO2 nanorods,graphene quantum dots
更新于2025-09-23 15:19:57
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Indirect voltammetric determination of thiomersal in influenza vaccine using photo-degradation and graphene quantum dots modified glassy carbon electrode
摘要： Thiomersal is an organomercury derivative that degrades producing thiosalicylic acid, dithiobenzoic acid and ethylmercury. It is widely used in topical pharmaceutical preparations and as preservative in vaccines and cosmetics. In this work, an electro-analytical method for thiomersal was developed using graphene quantum dots (GQDs) as a surface modifier of a glassy carbon electrode. The method rely on using square-wave voltammetry and exploring the synergistic effect between GQDs, visible radiation and the applied potential in producing very intense Hg oxidation peak during the anodic scan. A linear voltammetric response was obtained for the analyte in the concentration range from 3.0 μmol L-1 (1.2 μg mL-1) to 32 μmol L-1 (12 μg mL-1), with a detection limit of 0.9 m mol L-1 (0.34 m g mL-1). The proposed method was successfully applied for thiomersal determination in influenza vaccine.
关键词： Voltammetry,Graphene quantum dots,Mercury,Thiomersal,Influenza vaccine,Modified glassy carbon
更新于2025-09-23 15:19:57
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Color Sensitive Response of Graphene / Graphene Quantum Dot Phototransistors
摘要： We present the fabrication and characterization of all-carbon phototransistors made of graphene three terminal devices coated with atomically precise graphene quantum dots (GQD). Chemically synthesized GQDs are the light absorbing materials, while the underlying chemical vapor deposition (CVD)-grown graphene layer acts as the charge transporting channel. We investigated three types of GQDs with different sizes and edge structures, having distinct and characteristic optical absorption in the UV-Vis range. The photoresponsivity exceeds 106 A/W for vanishingly small incident power (<10-12 W), comparing well with state of the art sensitized graphene photodetectors. More importantly, the photoresponse is determined by the specific absorption spectrum of each GQD, exhibiting the maximal responsivity at the wavelengths corresponding to the absorption maxima. Overall this behavior can be ascribed to the efficient and selective absorption of light by the GQDs, followed by a charge transfer to graphene, a mechanism known as photogating effect. Our results suggest the use of graphene/GQD devices as valuable photodetectors for application where color sensitivity is required.
关键词： graphene,graphene quantum dots,phototransistors,color sensitivity,photogating effect
更新于2025-09-19 17:13:59
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Nitrogen‐functionalized Graphene Quantum Dots: A Versatile Platform for Integrated Optoelectronic Devices
摘要： Over the past 10 years, graphene quantum dots (GQDs) have grown into a highly innovative optical material in various research fields including electronics, photonics, biotechnologies, etc. With the increasing implementation of GQDs in these fields, GQDs with tunable optical properties will emerge that could be especially suitable for applications in the field of integrated photonics. Herein, a short summary of the recent state of our research on the development of nitrogen-functionalized GQDs with tunable optical properties and their integration into photodetectors is given.
关键词： Optical properties,Photodetectors,Chemical functionalization,Graphene,Graphene quantum dots
更新于2025-09-19 17:13:59
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One-step preparation of single-layered graphene quantum dots for the detection of Fe3+
摘要： Single-layer graphene quantum dots are highly desirable while their facile and controllable preparations remain challenging. Herein, single-layered graphene quantum dots (sl-GQDs) were developed via a facile one-step hydrothermal synthesis, with citric acid and β-cyclodextrin (CD) as starting materials. The sl-GQDs decorated with CD molecules emit green fluorescence with a quantum yield of 5.34%, and exhibit a good response exclusively to ferric ions for their structural oxygenous groups. The linear range of the proposed sensor for ferric ions was found in a wide concentration range of 0-85 μM. The detection limit is about 0.26 μM. The sl-GQDs based sensing platform also demonstrates its feasibility in real water sample analysis with recoveries of 93.8%-101.5%.
关键词： One-step preparation,β-cyclodextrin,Fluorescence sensing,Single-layered graphene quantum dots,Ferric ion
更新于2025-09-19 17:13:59
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Graphene Quantum Dot-Based Nanocomposites for Diagnosing Cancer Biomarker APE1 in Living Cells
摘要： As an essential DNA repair enzyme, apurinic/apyrimidinic endonuclease 1 (APE1) is overexpressed in most human cancers and is identified as a cancer diagnostic and predictive biomarker for cancer risk assessment, diagnosis, prognosis and prediction of treatment efficacy. Despite its importance in cancer, however, it is still a significant challenge nowadays to sense abundance variation and monitor enzymatic activity of this biomarker in living cells. Here, we report our construction of biocompatible functional nanocomposites, which are a combination of meticulously designed unimolecular DNA and fine-sized graphene quantum dots. Upon utilization of these nanocomposites as diagnostic probes, massive accumulation of fluorescence signal in living cells can be triggered by merely a small amount of cellular APE1 through repeated cycles of enzymatic catalysis. Most critically, our delicate structural designs assure that these graphene quantum dot-based nanocomposites are capable of sensing cancer biomarker APE1 in identical type of cells under different cell conditions and can be applied to multiple cancerous cells in highly sensitive and specific manners. This work not only brings about new methods for cytology-based cancer screening, but also lays down a general principle for fabricating diagnostic probes that target other endogenous biomarkers in living cells.
关键词： cancer diagnosis,biomarker,nanocomposites,DNA repair enzymes,graphene quantum dots
更新于2025-09-19 17:13:59
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Facile and highly effective synthesis of nitrogen-doped graphene quantum dots as a fluorescent sensing probe for Cu2+ detection
摘要： Nitrogen-doped graphene quantum dots (N-GQDs) with high blue fluorescence efficiency were synthesized by the hydrothermal method from p-Phenylenediamine and p-Coumaric acid. The N-GQDs possess several superiorities, most significantly in excellent solubility and superior photostability. Besides, the as-prepared N-GQDs exhibit a uniform size distribution with a diameter of about 3.8±0.5 nm. After dispersing the N-GQDs in water, the formed aqueous solution still presents a stable and homogeneous phase even after 2 months at room temperature. The N-GQD dispersion was further utilized as sensing probes for the selective detection of copper ions (Cu2+), which is realized by the photoluminescence (PL) quenching of N-GQDs after adding Cu2+. The detection limit for Cu2+ was found to be 57 nM L-1, with superior selectivity in the presence of other commonly interfering metal ions. The presented results in this study provide a facile and high-efficiency method for synthesizing N-GQDs, with ultra-high detectivity and selectivity for Cu2+ detection, offering numerous opportunities for the development of biosensing, bioimaging, environment monitoring, and others.
关键词： Nitrogen-doped graphene quantum dots,Hydrothermal method,Photoluminescence quenching,Cu2+ detection
更新于2025-09-19 17:13:59
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Facile, Gram-Scale and Eco-friendly Synthesis of Multi-Color Graphene Quantum Dots by Thermal-Driven Advanced Oxidation Process
摘要： Graphene quantum dots (GQDs) have been demonstrated of great potential and benefits in the fields of bioimaging and white light-emitting-diodes (WLEDs). However, it is still highly demanding at the current level to solve the dilemma of achieving high-yield GQDs of good quality and superior fluorescent property using low-cost sustainable and industrializable production procedure. In this work, we for the first time report the gram-scale synthesis of well-crystalline GQDs with ultra-small size based on thermal-driven Advanced Oxidation Process (AOP) under facile green hydrothermal conditions. The average yield calculated from 20 trials reached up to 60%, and the average size of the dots was measured to be ~3.7 nm. Furtherly, GQDs with the photoluminescence (PL) emission of blue, green, yellow, orange, and red have been prepared by expanding the π-conjugation and introducing graphite nitrogen in the carbon skeleton based on chemical structure engineering. The PL-tunable GQDs have an average size distribution of 2~5 nm and a lamellar structure of 2~6 layers. Structure analysis results have indicated that the red shift of PL emission is attributed to bandgap narrowing. This approach successfully converts the easily available and cheap precursor into high-valued products with great application potentials. The PL-tunable GQDs have been successfully used as fluorescent probes of good biocompatibility for in vitro/ in vivo bio-imaging and to produce highly-photostable white-light-emitting composite film with a quantum yield (QY) of 24%.
关键词： Gram-scale synthesis,White light-emitting-diodes,Photoluminescence,Bioimaging,Advanced Oxidation Process,Graphene quantum dots
更新于2025-09-19 17:13:59
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The role of GQDs additive in TiO2 nanorods as an electron transfer layer on performance improvement of the perovskite solar cells
摘要： The electron transport layer (ETL) plays an important role in improving the performance of the perovskite solar cells (PSCs). The main focus is on different types of TiO2 structures as an efficient ETL. In the present work, TiO2 nanorods (NRs) are prepared by a simple one-step hydrothermal method and employ as an ETL in PSCs. The power conversion efficiency (PCE) of the TiO2 NRs based PSCs is improved about 217% compared with the mesoporous (mp) TiO2 based cells. In order to further enhance PCE of the PSCs, a new approach is adopted to synthesize the graphene quantum dots- TiO2 NRs (GQDs- TiO2 NRs) by hydrothermal method. The PCE of PSCs based on GQDs- TiO2 NRs show improvement of 1.34 times compared to the TiO2 NRs. The GQDs- TiO2 NRs is capable of being a promising alternative to be employed as an efficient electron transport materials for photovoltaic devices.
关键词： TiO2 nanorods,Perovskite solar cells,Hydrothermal synthesis,Graphene quantum dots
更新于2025-09-19 17:13:59
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Highly efficient photocatalytic degradation of rhodamine B by conical graphene quantum dots/cerium oxide composite
摘要： Graphene Quantum Dots (GQDs) are graphene nanoparticles with a particle size of less than 100 nm. GQDs are used as sensitizers for semiconductor catalytic materials and have a significant enhancement effect on the catalytic performance of the catalyst. We have prepared GQDs/CeO2 composites to improve the catalytic performance of CeO2. GQDs in the GQDs/CeO2 composites were uniformly coated around each CeO2 crystal, which effectively increased the reactive sites and effective contact interfaces. The composite GQDs-4.5/CeO2 absorption edge was broadened to 475 nm, with extremely low electron-hole recombination rate and optimal photoelectric performance. The composite material formed a heterogeneous structure with staggered energy levels. The photogenerated electrons were transferred from the GQDs conduction band to the CeO2 conduction band, which effectively prolonged the carrier lifetime, showed enhanced photocatalytic activity, and decomposed Rhodamine B (RhB) photocatalytic reaction under visible light. The reaction rate constant was up to 13.8 times that of pure CeO2.
关键词： Composite,Photocatalytic,Cerium oxide,Graphene quantum dots
更新于2025-09-19 17:13:59