Two-step process for programmable removal of oxygen functionalities of graphene oxide: functional, structural and electrical characteristics

Dave, Kashyap; Park, Kyung Hee; Dhayal, Marshal

doi:10.1039/c5ra18880f

Cited by 118 publications

(65 citation statements)

References 103 publications

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“…The sp 3 carbon signal dominates in oxidized spiro-MeOTAD, and contrary to this, the sp 2 carbon signal dominates in spiro-MeOTAD, which is not oxidized. 23 As can be seen in Figure 2c, spiro-MeOTAD without Ag deposition has more sp 3 carbon, which means more oxidized spiro-MeOTAD was observed on the HTM surface.…”

Section: ■ Results and Discussionmentioning

confidence: 86%

Effect of Metal Electrodes on Aging-Induced Performance Recovery in Perovskite Solar Cells

Lee

Kim

Wang

et al. 2019

ACS Appl. Mater. Interfaces

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For commercialization of perovskite solar cells (PSCs), it is important to substitute the alternative electrode for Au to decrease the unit cost. From the early stage, Ag exhibits a potential to be a good counter electrode in PSCs; however, there is an abnormal s-shaped J−V curve with the Ag electrode, and it is recovered as time passes. The perception of the aging-induced recovery process and refutation of the raised stability issues are required for commercial application of Ag electrodes. Herein, we compared the aging effect of PSCs with Ag and Au electrodes and found that only devices with Ag electrodes have a dramatical aging-induced recovery process. We observed the change of photoelectronic properties only in the devices with Ag electrodes as time passes, which mainly contributes to recovery of the s-shaped J−V curve. We verified the work function change of an aged Ag electrode and its mechanism by photoelectron spectroscopy analysis. By comparing the light stability under 1 sun intensity illumination, we can assure the practical stability of Ag electrodes in case of being encapsulated. This work suggests the profound understanding of the aging-induced recovery process of PSCs and the possibility of commercial application of Ag electrodes.

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Section: ■ Results and Discussionmentioning

confidence: 86%

Effect of Metal Electrodes on Aging-Induced Performance Recovery in Perovskite Solar Cells

Lee

Kim

Wang

et al. 2019

ACS Appl. Mater. Interfaces

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“…The interplanar distance is slightly larger in rGO (0.36 nm) than in graphite (0.34 nm), suggesting the presence of some residual surface oxygen groups in rGO. The band at 43.18 • corresponds to the turbostratic band of disordered carbon materials [47].…”

Section: X-ray Diffraction Analysismentioning

confidence: 99%

Hydrothermal Synthesis of rGO-TiO2 Composites as High-Performance UV Photocatalysts for Ethylparaben Degradation

et al. 2020

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A series of reduced graphene oxide-TiO2 composites (rGO-TiO2) were prepared by hydrothermal treatment using graphite and titanium isopropoxide as raw materials. The structural, surface, electronic, and optical properties of the prepared composites were extensively characterized by N2 adsorption, FTIR, XRD, XPS, Raman spectroscopy, and DRS. GO was found to be effectively reduced and TiO2 to be in pure anatase phase in all composites obtained. Finally, experiments were performed to evaluate the effectiveness of these new materials as photocatalysts in the degradation of ethylparaben (EtP) by UV radiation. According to the band-gap energies obtained (ranging between 3.09 eV for 4% rGO-TiO2 to 2.55 eV for 30% rGO-TiO2), the rGO-TiO2 composites behave as semiconductor materials. The photocatalytic activity is highest with a rGO content of 7 wt% (7% rGO-TiO2), being higher than observed for pure TiO2 (Eg = 3.20 eV) and achieving 98.6% EtP degradation after only 40 min of treatment. However, the degradation yield decreases with higher percentages of rGO. Comparison with rGO-P25 composites showed that a better photocatalytic performance in EtP degradation is obtained with synthesized TiO2 (rGO-TiO2), probably due to the presence of the rutile phase (14.1 wt %) in commercial P25.

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“…All fitted peaks were constrained with FWHM in the range 1.0 -1.4 eV. Binding energies for sp 2 (C=C) and sp 3 (C-C/C-H) carbons, which mainly contribute to the 1 st peak at the lower binding energy of the C 1s spectra were assigned with seperation between peaks set to 0.6 eV [51][52][53][54]. C 1s peak assignments for the oxygon functional groups identified in IR spectra, namely C-OH and C-O-C which have similar binding energies are assigned at 287.0 ± 0.1 eV [30,[51][52]55].…”

Section: X-ray Diffractionmentioning

confidence: 99%

Evolution of oxygen functionalities in graphene oxide and its impact on structure and exfoliation: An oxidation time based study

Perera

Abeywickrama

Zen

et al. 2018

Materials Chemistry and Physics

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Control over oxygen functionalities is important for the realization of Graphene Oxide (GO) based applications. Evolution of oxygen functionalities with time of oxidation and its impact on GO structure, exfoliation and reduction is investigated using XRD, FTIR, XPS, TGA and AFM. The results indicate no net increase in oxygen bound carbon atoms compared to graphitic carbon within the samples studied. However the percentage contributions from each type of oxygen functionalities tend to vary as the oxidation progress. Changes in the thermogravimetric response were observed with continued oxidation that showed a change from one mass loss region to two mass loss regions. The interaction kinetics of the protective group and the spatial distribution of oxygen functionalities during graphite oxidation give key insight to the above observed properties in GO. It is also shown that the observed changes in the structure have a direct impact on the ability to exfoliate GO to single layers as well as on the reduction process to produce reduced graphene oxide. These results are significant in the scalable production of GO with controlled and consistent quality for applications in the areas such as chemical and biological sensing, water purification and development of nanocomposite.

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Two-step process for programmable removal of oxygen functionalities of graphene oxide: functional, structural and electrical characteristics

Abstract: Here we report a two-step programmable reduction of graphene oxide (GO) which was synthesized by oxidation of graphite.

Cited by 118 publications

References 103 publications

Effect of Metal Electrodes on Aging-Induced Performance Recovery in Perovskite Solar Cells

Effect of Metal Electrodes on Aging-Induced Performance Recovery in Perovskite Solar Cells

Hydrothermal Synthesis of rGO-TiO2 Composites as High-Performance UV Photocatalysts for Ethylparaben Degradation

Evolution of oxygen functionalities in graphene oxide and its impact on structure and exfoliation: An oxidation time based study

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