scholarly journals A Turn-On Fluorescent Sensor for Hg2+ Based on Graphene Oxide

2017 ◽  
Vol 2017 ◽  
pp. 1-5 ◽  
Author(s):  
Yong Wu He ◽  
Yi Feng ◽  
Lian Wei Kang ◽  
Xiao Liang Li
Keyword(s):  
Heavy Metal ◽  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Heavy Metal Ions ◽  
Charge Transfer Complex ◽  
Fluorescent Sensor ◽  
Force Microscopy ◽  
Turn On ◽  
Atomic Force ◽  
Ft Ir

A graphene oxide- (GO-) boradiazaindacenes (BODIPY) charge-transfer complex (BGO) has been easily synthesized, and the structure of BGO was confirmed by FT-IR and atomic force microscopy (AFM). Moreover, the BGO was found that could be used as a turn-on fluorescent sensor for Hg2+. Upon addition of Hg2+, the fluorescence of BGO would be enhanced since the energy transfer between BODIPY and GO was inhibited. The selectivity and the competition performance of BGO towards Hg2+ were good among other heavy metal ions.

Characterization of X-ray irradiated graphene oxide coatings using X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy

2013 ◽  
Vol 28 (2) ◽  
pp. 68-71 ◽  
Author(s):  
Thomas N. Blanton ◽  
Debasis Majumdar
Keyword(s):  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
High Energy ◽  
X Ray Diffraction ◽  
Carbon Phase ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After

In an effort to study an alternative approach to make graphene from graphene oxide (GO), exposure of GO to high-energy X-ray radiation has been performed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize GO before and after irradiation. Results indicate that GO exposed to high-energy radiation is converted to an amorphous carbon phase that is conductive.

scholarly journals Characterisation of InGaN by Photoconductive Atomic Force Microscopy

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1794 ◽  
Author(s):  
Thomas Weatherley ◽  
Fabien Massabuau ◽  
Menno Kappers ◽  
Rachel Oliver
Keyword(s):  
Atomic Force Microscopy ◽  
Cross Sections ◽  
Indium Content ◽  
Light Emitting ◽  
Force Microscopy ◽  
Turn On ◽  
Atomic Force ◽  
Voltage Curve ◽  
Current Voltage Curve ◽  
The Impact

Nanoscale structure has a large effect on the optoelectronic properties of InGaN, a material vital for energy saving technologies such as light emitting diodes. Photoconductive atomic force microscopy (PC-AFM) provides a new way to investigate this effect. In this study, PC-AFM was used to characterise four thick (∼130 nm) In x Ga 1 − x N films with x = 5%, 9%, 12%, and 15%. Lower photocurrent was observed on elevated ridges around defects (such as V-pits) in the films with x ≤ 12 %. Current-voltage curve analysis using the PC-AFM setup showed that this was due to a higher turn-on voltage on these ridges compared to surrounding material. To further understand this phenomenon, V-pit cross sections from the 9% and 15% films were characterised using transmission electron microscopy in combination with energy dispersive X-ray spectroscopy. This identified a subsurface indium-deficient region surrounding the V-pit in the lower indium content film, which was not present in the 15% sample. Although this cannot directly explain the impact of ridges on turn-on voltage, it is likely to be related. Overall, the data presented here demonstrate the potential of PC-AFM in the field of III-nitride semiconductors.

Graphene and graphene oxide nanogap electrodes fabricated by atomic force microscopy nanolithography

2010 ◽  
Vol 97 (13) ◽  
pp. 133301 ◽  
Author(s):  
Yudong He ◽  
Huanli Dong ◽  
Tao Li ◽  
Chengliang Wang ◽  
Wei Shao ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Force Microscopy ◽  
Atomic Force ◽  
Nanogap Electrodes

scholarly journals Measurements of the Electrical Conductivity of Monolayer Graphene Flakes Using Conductive Atomic Force Microscopy

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2575
Author(s):  
Soomook Lim ◽  
Hyunsoo Park ◽  
Go Yamamoto ◽  
Changgu Lee ◽  
Ji Won Suk
Keyword(s):  
Electrical Conductivity ◽  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Monolayer Graphene ◽  
Synthesis Methods ◽  
Clear Understanding ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Graphene Flakes

The intrinsic electrical conductivity of graphene is one of the key factors affecting the electrical conductance of its assemblies, such as papers, films, powders, and composites. Here, the local electrical conductivity of the individual graphene flakes was investigated using conductive atomic force microscopy (C-AFM). An isolated graphene flake connected to a pre-fabricated electrode was scanned using an electrically biased tip, which generated a current map over the flake area. The current change as a function of the distance between the tip and the electrode was analyzed analytically to estimate the contact resistance as well as the local conductivity of the flake. This method was applied to characterize graphene materials obtained using two representative large-scale synthesis methods. Monolayer graphene flakes synthesized by chemical vapor deposition on copper exhibited an electrical conductivity of 1.46 ± 0.82 × 106 S/m. Reduced graphene oxide (rGO) flakes obtained by thermal annealing of graphene oxide at 300 and 600 °C exhibited electrical conductivities of 2.3 ± 1.0 and 14.6 ± 5.5 S/m, respectively, showing the effect of thermal reduction on the electrical conductivity of rGO flakes. This study demonstrates an alternative method to characterizing the intrinsic electrical conductivity of graphene-based materials, which affords a clear understanding of the local properties of individual graphene flakes.

scholarly journals Mechanical Characterization of Reduced Graphene Oxide Using AFM

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Alem Teklu ◽  
Canyon Barry ◽  
Matthew Palumbo ◽  
Collin Weiwadel ◽  
Narayanan Kuthirummal ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Young’S Modulus ◽  
Reduced Graphene Oxide ◽  
Young's Modulus ◽  
Force Microscopy ◽  
Atomic Force ◽  
Reduction Cycle ◽  
Reduced Graphene ◽  
Oxide Sample

Nanoindentation coupled with Atomic Force Microscopy was used to study stiffness, hardness, and the reduced Young’s modulus of reduced graphene oxide. Oxygen reduction on the graphene oxide sample was performed via LightScribe DVD burner reduction, a cost-effective approach with potential for large scale graphene production. The reduction of oxygen in the graphene oxide sample was estimated to about 10 percent using FTIR spectroscopic analysis. Images of the various samples were captured after each reduction cycle using Atomic Force Microscopy. Elastic and spectroscopic analyses were performed on the samples after each oxygen reduction cycle in the LightScribe, thus allowing for a comparison of stiffness, hardness, and the reduced Young’s modulus based on the number of reduction cycles. The highest values obtained were after the fifth and final reduction cycle, yielding a stiffness of 22.4 N/m, a hardness of 0.55 GPa, and a reduced Young’s modulus of 1.62 GPa as compared to a stiffness of 22.8 N/m, a hardness of 0.58 GPa, and a reduced Young’s modulus of 1.84 GPa for a commercially purchased graphene film made by CVD. This data was then compared to the expected values of pristine single layer graphene. Furthermore, two RC circuits were built, one using a parallel plate capacitors made of light scribed graphene on a kapton substrate (LSGC) and a second one using a CVD deposited graphene on aluminum (CVDGC). Their RC time constants and surface charge densities were compared.

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