Etching with atomic hydrogen, as a preparation step before the high-temperature growth process of graphene onto a thin 3C-SiC film grown on Si(111), greatly improves the structural quality of topmost graphene layers. Pit formation and island coalescence, which are typical of graphene growth by SiC graphitization, are quenched and accompanied by widening of the graphene domain sizes to hundreds of nanometers, and by a significant reduction in surface roughness down to a single substrate bilayer. The surface reconstructions expected for graphene and the underlying layer are shown with atomic resolution by scanning tunnelling microscopy. Spectroscopic features typical of graphene are measured by core-level photoemission and Raman spectroscopy.
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http://dx.doi.org/10.1088/1361-6528/aa5a48 | DOI Listing |
ACS Appl Nano Mater
December 2024
Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States.
The transfer of large-area, continuous, chemical vapor deposition (CVD)-grown graphene without introducing defects remains a challenge for fabricating graphene-based electronics. Polymer thin films are commonly used as supports for transferring graphene, but they typically require thermal annealing before transfer. However, little work has been done to thoroughly investigate how thermal annealing affects the polymer/graphene thin film when directly annealed on the growth substrate.
View Article and Find Full Text PDFSci Rep
December 2024
Department of Chemistry, Faculty of Science, K. N. Toosi University of Technology, P.O. Box 15875-4416, Tehran, Iran.
This research presents an innovative approach for synthesizing 2-amino-4H-chromene derivatives, utilizing 30 mg of NS-doped graphene oxide quantum dots (GOQDs) as a catalyst in a one-pot, three-component reaction conducted in ethanol. The NS-doped GOQDs were synthesized using a cost-effective bottom-up method through the condensation of citric acid (CA) with thiourea and the reaction was carried out at 185 C, resulting in the elimination of water. The catalytic performance of the synthesized NS-doped GOQDs resulted in high product yields, achieving up to 98% for the 2-amino-4H-chromene derivatives from aromatic aldehydes, malononitrile, resorcinol, -naphthol, and dimedone.
View Article and Find Full Text PDFBiosensors (Basel)
December 2024
Guangdong Laboratory of Artificial Intelligence and Digital Economy (SZ), Shenzhen 518107, China.
The demand for non-invasive, real-time health monitoring has driven advancements in wearable sensors for tracking biomarkers in sweat. Ammonium ions (NH) in sweat serve as indicators of metabolic function, muscle fatigue, and kidney health. Although current ion-selective all-solid-state printed sensors based on nanocomposites typically exhibit good sensitivity (~50 mV/log [NH]), low detection limits (LOD ranging from 10 to 10 M), and wide linearity ranges (from 10 to 10 M), few have reported the stability test results necessary for their integration into commercial products for future practical applications.
View Article and Find Full Text PDFNanoscale
December 2024
Computational Biotechnology, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany.
Nanopores drilled in materials can electrophoretically drive charged biomolecules to enable their detection. Here, we explore and compare two-dimensional nanopores, graphene and MoS, in order to unravel their advantages and disadvantages with regard to protein detection. We tuned the protein translocation and its dynamics by the choice and concentration of the surrounding solvent.
View Article and Find Full Text PDFLangmuir
December 2024
International Iberian Nanotechnology Laboratory, 4715-330 Braga, Portugal.
This study investigates the effect of different linkers and solvents on the immobilization of DNA probes on graphene surfaces, which are crucial for developing high-performance biosensors. Quartz crystal microbalance with dissipation (QCM-D) measurements were used to characterize in situ and real-time the immobilization of ssDNA and hybridization efficiency on model graphene surfaces. The DNA probes immobilization kinetics and thermodynamics were systematically investigated for all the pairings between three bifunctional linkers─1-pyrenebutyric acid succinimidyl ester (PBSE), Fluorenylmethylsuccinimidyl carbonate (FSC), and Acridine Orange (AO) succinimidyl ester─and three organic solvents (DMF, DMSO, and 10% DMF/ethanol).
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