Photoluminescence (PL) spectroscopy is one of the best methods to detect molecules due to its easiness, fast time of analysis and high sensitivity. In addition, zinc oxide (ZnO) possesses good optical properties and particularly PL emission in these materials have been exploited for their potential use as photocatalyst, light harvesting and photosensor. These PL properties enhance when graphene quantum dots (GQD) are added to ZnO. For these reasons, we investigated the PL performance of ZnO-GQD nanocomposites. In one experiment we evaluated the PL emission of solid samples ZnO and ZnO-GQD. In a second experiment, these samples were also evaluated in aqueous phase to investigate the HO effect during an experiment lasting 170 minutes. Both experiments displayed six peaks and they were related to the same PL emission source. The PL emission peak around 415 nm was found to be principal source where GQD are interacting. By varying the GQD amount to low, medium, and high concentration, the effect of HO acted consequently, altering the PL emission during experiment in aqueous phase. An oxygen rich environment (ORE) occurred due to HO which oxides the ZnO surface. Low GQD concentration resulted affected by an ORE weakening the GQD-ZnO contact, decreasing PL emission. In high GQD concentration, HO induced GQD to reach the ZnO surface, increasing the PL emission. Only medium GQD concentration prevented oxidation of ZnO and maintained the PL emission intensity constant. When HO concentration increased, for the medium GQD concentration, an excess of charge by peroxides inhibited the charge transfer from GQD to ZnO. This inhibition produces a quenching of the PL emission.
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http://dx.doi.org/10.1016/j.heliyon.2024.e31144 | DOI Listing |
Sci Rep
December 2024
Department of Petroleum and Geoenergy Engineering, Amirkabir University of Technology, Tehran, Iran.
Nanofluids have the capacity to reduce interfacial tension (IFT) of crude oil and water for enhanced oil recovery (EOR) operations, but traditional nanoparticles are limited in tight reservoirs due to their inappropriate size for micro-nano pores and their tendency to aggregate. In this paper, Graphene Quantum Dots (GQDs) with simple and favorable properties are developed, and their performance and mechanism for reducing IFT are evaluated. The paper also aims to explore the effects of GQD precursor type, synthesis duration, and molar percentages of precursors on reducing IFT.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Institute of Optoelectronics Technology, Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Beijing 100044, China.
This work explores the carrier recombination dynamics of AC-driven quantum dot (QD) light-emitting diodes (AC-QLEDs) and proposes their application in the field of electric field contactless detection. Different sequences of green QD (GQD)/red QD (RQD) bilayer thin films as the emission layer of AC-QLEDs were fabricated via film transfer printing to ensure the complete morphology of each layer. AC-QLEDs with the emission layer as the sequence of GQD + RQD (GR-QLEDs) show a significantly enhanced carrier recombination efficiency due to its stable energy level structure, achieving the highest peak brightness ever recorded for vertically emitting brightness of 1648.
View Article and Find Full Text PDFChemosphere
February 2025
College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin, 300350, China. Electronic address:
Graphene quantum dot (GQD), as one of the smallest graphene nanomaterials (GNMs), has the potential to be widely used due to its excellent fluorescence properties, hydrophilicity, and good biocompatibility. GQD remaining in water will generate DBPs when entering the disinfection process, and whether the generation mechanism and influencing factors are similar to those of other GNMs has not been proven and thoroughly investigated. In this study, the total amount, effect, and mechanism of DBPs formation from GQD chlorination were investigated and compared with graphene oxide (GO) and graphene.
View Article and Find Full Text PDFHeliyon
June 2024
Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, Lab. Mat. I, Av. Pedro de Alba s/n, San Nicolás de los Garza, 66455, Nuevo León, Mexico.
Micromachines (Basel)
October 2024
CBRN Defense Technologies R&D Group, Materials and Process Technologies, The Scientific and Technological Research Council of Türkiye (TÜBİTAK), Marmara Research Center, Kocaeli 41470, Türkiye.
Biological warfare agents are infectious microorganisms or toxins capable of harming or killing humans. is a potential bioterrorism agent that is highly infectious, even at very low doses. Biosensors for biological warfare agents are simple yet reliable point-of-care analytical tools.
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