Synthesis and Characterisations of Reduced Graphene Oxide Prepared by Microwave Irradiation with Sonication

Recently, reducing graphene oxide (GO) through microwave irradiation has been extensively explored in order to scale up the mass production of graphene. We report the simple technique to reduce GO by means of microwave irradiation combined with a sonication technique. The microwave-reduced GO (MWrGO) is formed by exposing a microwave onto GO powder in order to reduce the oxygen functional group and then followed by exfoliating via a sonication method. The time exposure of the microwave irradiation was 20 min with the powers of 450 W and 800 W. The UV-visible (UV-vis) spectra showed the evolution of GO into MWrGO indicated by the red shift of the absorption peak from 230 nm to 267 nm and disappearance of the shouldering peak at 300 nm. The reduction of the oxygen functional group has been proved by Fourier transform infrared (FTIR) spectra. Furthermore, the scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) data demonstrated further confirmation of the reduction of GO and the formation of basal planes of sp2 carbon clusters of the sample due to the treatment. The EDS spectra revealed that the MWrGO by 800-W-irradiation had much less oxygen functional groups and much more carbon content than GO. The proposed synthesis method is simple and readily controlled for a mass production of graphene from GO.

Novel Exfoliation of High-Quality 2H-MoS2 Nanoflakes for Solution-Processed Photodetector

Highly dispersive molybdenum disulfide nanoflakes (MoS2 NFs), without any phase transition during the exfoliation process, are desirable for full utilization of their semiconductor properties in practical applications. Here, we demonstrate an innovate approach for fabricating MoS2 NFs by using hydrazine-assisted ball milling via the synergetic effect of chemical intercalation and mechanical exfoliation. The NFs obtained have a lateral size of 600–800 nm, a thickness less than 3 nm, and high crystallinity in the 2H semiconducting phase. They form a stable dispersion in various solvents, which will be helpful for many applications, due to the oxygen functional group. To investigate production of a two-dimensional (2D) photodetector, 2D semiconducting MoS2, MoS2–p-Si vertical devices were fabricated, and their optical properties were characterized. The photodiode exhibited consistent responses with excellent photo-switching characteristics with wavelengths of 850, 530, and 400 nm.

Quinone/ester-based oxygen functional group-incorporated full carbon Li-ion capacitor for enhanced performance

Lithium ion capacitors (LICs) are regarded as one of the most promising energy storage devices since they can bridge the gap between lithium ion batteries and supercapacitors.

Shallow trap state-enhanced photocatalytic hydrogen evolution over thermal-decomposed polymeric carbon nitride

Oxygen functional group-introduced shallow electron trap states enhance the photocatalytic activity of the thermal-decomposed polymeric carbon nitride for hydrogen evolution.

Unusual formation of hollow NiCoO2 sub-microspheres by oxygen functional group dominated thermally induced mass relocation towards efficient lithium storage

The unique oxygen functional group dominated thermally induced mass relocation strategy was first purposefully explored for controllable synthesis of uniform NiCoO2 hollow spheres with enhanced lithium-storage behaviors for LIBs.

The Influences of Chemical and Mechanical Treatment on the Morphology of Carbon Nanofibers

Oxidation by acid treatment is one of the chemical methods used to introduce surface oxygen functional group (SOFG) and defects on the surface of carbon nanofibers (CNFs). Therefore, many researchers used this method to improve the dispersion ability of CNFs in aqueous media. However, only few researchers used combination of chemical and mechanical method for oxidation of CNFs. In this work, as-received CNFs were treated using chemical method with an addition of mechanical method. On the first experiment (Method A) concentrated sulphuric acid and nitric acid were used and followed by combinations of mechanical method using ultrasonication water bath under reflux. The addition mechanical method through reflux was eliminated and different times of ultrasonication were used in method B and method C. Outer diameter of each CNFs samples were determined from FESEM images and were found to be in range of 50 nm–190 nm. Whereas, Raman spectroscopy was used to analyse any structural defects of CNFs samples during each treatment methods. From the findings, acid treatment of CNFs with addition of mechanical method using ultrasonication showed remarkably effect on the CNFs morphology.