Preparation Of Graphene Films Research Articles

Research Progress on the Preparation of Graphene Films through Carbonization of Polymers in Stacked Structures

Research Progress on the Preparation of Graphene Films through Carbonization of Polymers in Stacked Structures

One Step Synthesis of Nitrogen-Doped Graphene from Naphthalene and Urea by Atmospheric Chemical Vapor Deposition

Heavy metal pollutants in wastewater are a major environmental concern. In order to fabricate metal organic composite for adsorption of these pollutants, in a first step a pristine and several nitrogen doped graphene films were synthesized by chemical vapor deposition method. Preparation of graphene films was performed through a one-step co-growth of naphthalene and urea mixture as an inexpensive and easy technique to handle solid precursors. This was done over a copper catalyst at different growth temperatures. Different characterization methods including Raman spectroscopy, elemental analysis, and X-ray diffraction confirmed the quality of the pristine and doped graphene. This technique showed an increasing trend of the doping level (nitrogen concentration up to 5.1% overall) as the growth temperature decreased. Results showed that both nitrogen doping, and carrying the synthesis at higher temperatures increase the defects and wrinkles in the graphene. Furthermore, doping introduced a light shift in defect types from vacancy in pristine graphene to boundary type in nitrogen-doped samples, which are favorable for functionalization for environmental applications.

The Nucleation Process in the Preparation of Graphene Films by Pulsed Laser Deposition

The nucleation process of graphene films prepared by pulsed laser deposition has been investigated in detail. It is found that graphene nucleates at the steps on the substrate surface firstly, from aggregation of nuclei into particles. High pulsed laser energy offers large incident energy for carbon particles deposited on the surface of the substrate, which is beneficial to the nucleation of graphene. A lot of steps are formed on the copper substrate due to the high temperature, so that the high incident energetic carbon species are able to form a stable nucleus at the steps. As the incident particles increases, the graphene nuclei are combined to grow together. Further, it is found that graphene tends to form few layer graphene particles instead of large graphene sheets.

Exfoliation of graphite in various electrolytes and preparation of graphene films via electrochemical approach

Graphene, exhibiting superior mechanical, thermal, optical and electronic properties, has attracted great interest. Anodic exfoliation of graphite has emerged as an attractive method to access graphene nanosheets in large quantities. In this work, electrochemical exfoliation used to synthesize graphene oxide (GO) flakes in different aqueous electrolytes with various concentrations and voltages is reported. The prepared GO powders were subjected to different characterizations and (NH4)2SO4 was found the best suited starting material for preparation of graphene thin films. The exfoliated graphene sheets exhibited lateral size of about 2 μm and contained only a few graphene layers. The graphene powder was spin-coated on glass substrates under different conditions such as graphene suspension concentration, spin time and speed. Then the electrical and optical properties of the prepared samples were studied as functions of chemical reduction and combination of chemical and thermal reduction treatments. It was noted that applying the later treatment, resulted in optimal graphene films with high transmittance of 73% and low sheet resistance of 22.31 kΩ/sq.

Graphene growth by transfer-free chemical vapour deposition on a cobalt layer

Abstract The contribution deals with the preparation of graphene films by a transfer-free chemical vapour deposition process utilizing a thin cobalt layer. This method allows growing graphene directly on a dielectric substrate. The process was carried out in a cold-wall reactor with methane as carbon precursor. We managed to prepare bilayer graphene. The best results were obtained for a structure with a cobalt layer with a thickness of 50 nm. The quality of prepared graphene films and of the number of graphene layers were estimated using Raman spectroscopy. with a minimal dots diameter of 180 nm and spacing of 1000 nm were successfully developed.

Growth of three-dimensional graphene layers using plasma enhanced CVD

Since its discovery, graphene has been the star material either in scientific studies or potentially technical applications. There are various methods for preparation of graphene films (e.g. mechanical exfoliation, epitaxial growth, molecular assembly, chemical vapour deposition, thermal photocatalysis, and chemical or electrochemical reduction of graphene oxide). In this article, we briefly reviewed the growths of three-dimensional graphene films on metallic and non-metallic substrates using plasma enhanced chemical vapour deposition by emphasising on their growth mechanisms. Since this technique is still in its early stage, the general absence in understanding of the graphene growth processes is thus needed to be clarified. Moreover the utility of plasma enhanced chemical vapour deposition allows synthesis of graphene films at relatively low temperatures and therefore it is possible to directly grow graphene on the substrates that could not survive at high temperatures.

Preparation of Graphene Films and their Applications in Dye-Sensitized Solar Cells

A facile and rapid deposition process is developed for the fabrication of large-area graphene films by scalpel technology using graphene nanopartical as material. Graphite oxide (GO) was synthesized using modified Hummers method. Graphene nanopartical was fabricated by a reducing process in which GO was well reduced by hydrazine hydrate. The crystal structure and photoelectric properties of graphene and graphene films were investigated by X-ray diffraction. The composition of production (GO and graphene) is investigated by Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy technology. Surface morphology of graphene layers were observed by SEM. Then, the semitransparent conductive films were applied to backside illumination DSSC. As a result, the maximum power conversion efficiency (PCE) is as high as 0.2558% and the fill factor is 30.97%.