scholarly journals Electronic Transport Mechanisms Correlated to Structural Properties of a Reduced Graphene Oxide Sponge

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2503
Author(s):  
Nicola Pinto ◽  
Benjamin McNaughton ◽  
Marco Minicucci ◽  
Milorad V. Milošević ◽  
Andrea Perali
Keyword(s):  
Structural Properties ◽  
Room Temperature ◽  
Defect Density ◽  
Structural Disorder ◽  
Charge Carriers ◽  
Quantum Tunnelling ◽  
Graphene Sponge ◽  
Reduced Graphene ◽  
Spongy Texture ◽  
Oxygen Ratio

We report morpho-structural properties and charge conduction mechanisms of a foamy “graphene sponge”, having a density as low as ≈0.07 kg/m3 and a carbon to oxygen ratio C:O ≃ 13:1. The spongy texture analysed by scanning electron microscopy is made of irregularly-shaped millimetres-sized small flakes, containing small crystallites with a typical size of ≃16.3 nm. A defect density as high as ≃2.6 × 1011 cm−2 has been estimated by the Raman intensity of D and G peaks, dominating the spectrum from room temperature down to ≃153 K. Despite the high C:O ratio, the graphene sponge exhibits an insulating electrical behavior, with a raise of the resistance value at ≃6 K up to 5 orders of magnitude with respect to the room temperature value. A variable range hopping (VRH) conduction, with a strong 2D character, dominates the charge carriers transport, from 300 K down to 20 K. At T < 20 K, graphene sponge resistance tends to saturate, suggesting a temperature-independent quantum tunnelling. The 2D-VRH conduction originates from structural disorder and is consistent with hopping of charge carriers between sp2 defects in the plane, where sp3 clusters related to oxygen functional groups act as potential barriers.

scholarly journals Electronic Transport Mechanisms Correlated to Structural Properties of a Reduced Graphene Oxide Sponge

2021 ◽  
Author(s):  
Nicola Pinto ◽  
Benjamin A. McNaughton ◽  
Marco Minicucci ◽  
Milorad V. Milošević ◽  
Andrea Perali
Keyword(s):  
Structural Properties ◽  
Room Temperature ◽  
Defect Density ◽  
Structural Disorder ◽  
Charge Carriers ◽  
Quantum Tunnelling ◽  
Graphene Sponge ◽  
Reduced Graphene ◽  
Spongy Texture ◽  
Oxygen Ratio

We report morpho-structural properties and charge conduction mechanisms of a foamy &ldquo;graphene sponge&rdquo;, having a density as low as &asymp; 0.07 kg/m3 and a carbon to oxygen ratio C:O ≃ 13:1. The spongy texture analysed by scanning electron microscopy is made of irregularly-shaped millimetres-sized small flakes, containing small crystallites with a typical size of ≃ 16.3 nm. A defect density as high as ≃ 2.6&times;1011 cm&minus;2 has been estimated by the Raman intensity of D and G peaks, dominating the spectrum from room temperature down to ≃ 153 K. Despite the high C:O ratio, the graphene sponge exhibits an insulating electrical behavior, with a raise of the resistance value at ≃ 6 K up to 5 orders of magnitude with respect to the room temperature value. A variable range hopping (VRH) conduction, with a strong 2D character, dominates the charge carriers transport, from 300 K down to 20 K. At T&amp;lt; 20 K, graphene sponge resistance tends to saturate, suggesting a temperature-independent quantum tunnelling. The 2D-VRH conduction originates from structural disorder and is consistent with hopping of charge carriers between sp2 defects in the plane, where sp3 clusters related to oxygen functional groups act as potential barriers.

Laser Engineering of Barrier Structures Based on Solid Solution ZnCdHgTe.

2002 ◽  
Vol 719 ◽  
Author(s):  
Galina Khlyap
Keyword(s):  
Room Temperature ◽  
Film Surface ◽  
Charge Carriers ◽  
Barrier Structure ◽  
Free Charge ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Laser Engineering ◽  
Charged Defects ◽  
Epilayer Surface

AbstractRoom-temperature electric investigations carried out in CO2-laser irradiated ZnCdHgTe epifilms revealed current-voltage and capacitance-voltage dependencies typical for the metal-semiconductor barrier structure. The epilayer surface studies had demonstrated that the cell-like relief has replaced the initial tessellated structure observed on the as-grown samples. The detailed numerical analysis of the experimental measurements and morphological investigations of the film surface showed that the boundaries of the cells formed under the laser irradiation are appeared as the regions of accumulation of derived charged defects of different type of conductivity supplying free charge carriers under the applied electric field.

Photo-Current Enhancement at Cu/p-Cu2O/rGO- Electrolyte Interface

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
S.P.A.U.K. Samarakoon ◽  
C.A.N. Fernando
Keyword(s):  
Diffuse Reflectance ◽  
Electrochemical Cell ◽  
Time Development ◽  
Charge Carriers ◽  
Electrochemical Cells ◽  
Current Action ◽  
Electrolyte Interface ◽  
Reduced Graphene ◽  
Efficient Charge ◽  
Photo Current

A considerable photo-current enhancement was found at the Cu/p-Cu2O/rGO-electrolyte interface in a photo-electrochemical cell with compared to that of Cu/p-Cu2O-electrolyte interface. The reason for the photo-current enhancement may be due to the efficient charge separation process provided at Cu/p-Cu2O/rGO-electrolyte interface. Here rGO (reduced graphene oxide) acts as an electron acceptor for the photo-generated charge carriers as it readily accept electrons from the conduction band of p-Cu2O. rGO was synthesized using electro-phoretic deposition (EPD) technique. Fabricated samples were characterized using diffuse reflectance spectra, photo-current action spectra and the time development of the photocurrent of photo-electrochemical cells.

Polyaniline-Reduced Graphene Oxide Nanosheets for Room Temperature NH3 Detection

2021 ◽  
Author(s):  
Junyu Chang ◽  
Xiaobo Zhang ◽  
Zhenming Wang ◽  
Chunsheng Li ◽  
Qi Hu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Room Temperature ◽  
Graphene Oxide Nanosheets ◽  
Reduced Graphene

scholarly journals Functionalized Reduced Graphene Oxide Thin Films for Ultrahigh CO2 Gas Sensing Performance at Room Temperature

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 623
Author(s):  
Monika Gupta ◽  
Huzein Fahmi Hawari ◽  
Pradeep Kumar ◽  
Zainal Arif Burhanudin ◽  
Nelson Tansu
Keyword(s):  
Thin Films ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Gas Sensor ◽  
Functional Groups ◽  
Recovery Time ◽  
Room Temperature ◽  
Co2 Gas ◽  
Reduced Graphene ◽  
Response And Recovery

The demand for carbon dioxide (CO2) gas detection is increasing nowadays. However, its fast detection at room temperature (RT) is a major challenge. Graphene is found to be the most promising sensing material for RT detection, owing to its high surface area and electrical conductivity. In this work, we report a highly edge functionalized chemically synthesized reduced graphene oxide (rGO) thin films to achieve fast sensing response for CO2 gas at room temperature. The high amount of edge functional groups is prominent for the sorption of CO2 molecules. Initially, rGO is synthesized by reduction of GO using ascorbic acid (AA) as a reducing agent. Three different concentrations of rGO are prepared using three AA concentrations (25, 50, and 100 mg) to optimize the material properties such as functional groups and conductivity. Thin films of three different AA reduced rGO suspensions (AArGO25, AArGO50, AArGO100) are developed and later analyzed using standard FTIR, XRD, Raman, XPS, TEM, SEM, and four-point probe measurement techniques. We find that the highest edge functionality is achieved by the AArGO25 sample with a conductivity of ~1389 S/cm. The functionalized AArGO25 gas sensor shows recordable high sensing properties (response and recovery time) with good repeatability for CO2 at room temperature at 500 ppm and 50 ppm. Short response and recovery time of ~26 s and ~10 s, respectively, are achieved for 500 ppm CO2 gas with the sensitivity of ~50 Hz/µg. We believe that a highly functionalized AArGO CO2 gas sensor could be applicable for enhanced oil recovery, industrial and domestic safety applications.

scholarly journals Ferromagnetic Behaviors in Fe-Doped NiO Nanofibers Synthesized by Electrospinning Method

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Yi-Dong Luo ◽  
Yuan-Hua Lin ◽  
Xuehui Zhang ◽  
Deping Liu ◽  
Yang Shen ◽  
...  
Keyword(s):  
Room Temperature ◽  
Doping Concentration ◽  
Double Exchange ◽  
Host Lattice ◽  
Charge Carriers ◽  
Fe Doping ◽  
Free Charge ◽  
Ferromagnetic Properties ◽  
Electrospinning Method ◽  
Fe Ions

Ni1−xFexOnanofibers with different Fe doping concentration have been synthesized by electrospinning method. An analysis of the phase composition and microstructure shows that Fe doping has no influence on the crystal structure and morphology of NiO nanofibers, which reveals that the doped Fe ions have been incorporated into the NiO host lattice. Pure NiO without Fe doping is antiferromagnetic, yet all the Fe-doped NiO nanofiber samples show obvious room-temperature ferromagnetic properties. The saturation magnetization of the nanofibers can be enhanced with increasing Fe doping concentration, which can be ascribed to the double exchange mechanism through the doped Fe ions and free charge carriers. In addition, it was found that the diameter of nanofibers has significant impact on the ferromagnetic properties, which was discussed in detail.

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