Eui Jung Kim

Bio: Eui Jung Kim is an academic researcher from University of Ulsan. The author has contributed to research in topics: Graphene & Thin film. The author has an hindex of 46, co-authored 133 publications receiving 6563 citations.

Chemical functionalization of graphene sheets by solvothermal reduction of a graphene oxide suspension in N-methyl-2-pyrrolidone

Abstract: We report a simple and effective method for reducing and functionalizing graphene oxide into chemically converted graphene by solvothermal reduction of a graphene oxide suspension in N-methyl-2-pyrrolidone (NMP). Graphene oxide sheets were functionalized by free radicals generated during heating of NMP in the presence of air. The degree of functionalization was easily controlled by manipulating the reduction time. High functionalized solvothermally reduced graphene oxide (STRG) shows superior dispersibility in various organic solvents, while slightly functionalized STRG shows excellent electrical conductivity. The superior dispersibility of highly functionalized STRG in organic solvents was attributed to the steric effect of functionalized groups on the surface of STRG sheets. Free-standing STRG paper that was reduced for 1 h exhibited electrical conductivity as high as 21600 S m−1, while the dispersibility of STRG that was reduced for 5 h was as high as 1.4 mg mL−1.

Highly Conductive Poly(methyl methacrylate) (PMMA)-Reduced Graphene Oxide Composite Prepared by Self-Assembly of PMMA Latex and Graphene Oxide through Electrostatic Interaction

Abstract: We report a simple, environmentally friendly approach for preparing highly conductive poly(methyl methacrylate)–reduced graphene oxide (PMMA-RGO) composites by self-assembly of positively charged PMMA latex particles and negatively charged graphene oxide sheets through electrostatic interactions, followed by hydrazine reduction. The PMMA latex was prepared by surfactant-free emulsion polymerization using a cationic free radical initiator, which created the positive charges on the surface of the PMMA particle. By mixing PMMA latex with a graphene oxide dispersion, positively charged PMMA particles easily assembled with negatively charged graphene oxide sheets through electrostatic interaction. The obtained PMMA-RGO exhibited excellent electrical properties with a percolation threshold as low as 0.16 vol % and an electrical conductivity of 64 S/m at only 2.7 vol %. Moreover, the thermomechanical properties of PMMA-RGO were also significantly improved. The storage modulus of PMMA-RGO increased by about 30% a...

Graphene oxide as a chemically tunable platform for optical applications

Abstract: Chemically derived graphene oxide (GO) is an atomically thin sheet of graphite that has traditionally served as a precursor for graphene, but is increasingly attracting chemists for its own characteristics. It is covalently decorated with oxygen-containing functional groups - either on the basal plane or at the edges - so that it contains a mixture of sp(2)- and sp(3)-hybridized carbon atoms. In particular, manipulation of the size, shape and relative fraction of the sp(2)-hybridized domains of GO by reduction chemistry provides opportunities for tailoring its optoelectronic properties. For example, as-synthesized GO is insulating but controlled deoxidation leads to an electrically and optically active material that is transparent and conducting. Furthermore, in contrast to pure graphene, GO is fluorescent over a broad range of wavelengths, owing to its heterogeneous electronic structure. In this Review, we highlight the recent advances in optical properties of chemically derived GO, as well as new physical and biological applications.

Heterogeneous photocatalytic degradation of organic contaminants over titanium dioxide : A review of fundamentals, progress and problems

Abstract: Even though heterogeneous photocatalysis appeared in many forms, photodegradation of organic pollutants has recently been the most widely investigated. By far, titania has played a much larger role in this scenario compared to other semiconductor photocatalysts due to its cost effectiveness, inert nature and photostability. Extensive literature analysis has shown many possibilities of improving the efficiency of photodecomposition over titania by combining the photoprocess with either physical or chemical operations. The resulting combined processes revealed a flexible line of action for wastewater treatment technologies. The choice of treatment method usually depends upon the composition of the wastewater. However, a lot more is needed from engineering design and modelling for successful application of the laboratory scale techniques to large-scale operation. The present review paper seeks to offer an overview of the dramatic trend in the use of the TiO 2 photocatalyst for remediation and decontamination of wastewater, report the recent work done, important achievements and problems.

Graphene-based semiconductor photocatalysts

Abstract: Graphene, a single layer of graphite, possesses a unique two-dimensional structure, high conductivity, superior electron mobility and extremely high specific surface area, and can be produced on a large scale at low cost. Thus, it has been regarded as an important component for making various functional composite materials. Especially, graphene-based semiconductor photocatalysts have attracted extensive attention because of their usefulness in environmental and energy applications. This critical review summarizes the recent progress in the design and fabrication of graphene-based semiconductor photocatalysts via various strategies including in situ growth, solution mixing, hydrothermal and/or solvothermal methods. Furthermore, the photocatalytic properties of the resulting graphene-based composite systems are also discussed in relation to the environmental and energy applications such as photocatalytic degradation of pollutants, photocatalytic hydrogen generation and photocatalytic disinfection. This critical review ends with a summary and some perspectives on the challenges and new directions in this emerging area of research (158 references).

Graphene-Based Materials: Synthesis, Characterization, Properties, and Applications

Abstract: Graphene, a two-dimensional, single-layer sheet of sp(2) hybridized carbon atoms, has attracted tremendous attention and research interest, owing to its exceptional physical properties, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Other forms of graphene-related materials, including graphene oxide, reduced graphene oxide, and exfoliated graphite, have been reliably produced in large scale. The promising properties together with the ease of processibility and functionalization make graphene-based materials ideal candidates for incorporation into a variety of functional materials. Importantly, graphene and its derivatives have been explored in a wide range of applications, such as electronic and photonic devices, clean energy, and sensors. In this review, after a general introduction to graphene and its derivatives, the synthesis, characterization, properties, and applications of graphene-based materials are discussed.