The number of dopant atoms is a parameter that can effectively tune the electronic and magnetic properties of graphitic and pyridinic N-doped graphene.
Magnetism of reduced graphene oxide/rGO prepared by a green synthesis method from coconut shells (rGO-s) and the commercial product (rGO-c, ®Graphenea) have been investigated. Similar magnetic feature of a weak ferromagnetism concomitant with diamagnetic nature was observed in both samples. At 300 K, the saturation magnetization (MS) of rGO-s is approximately 14×10-3 emu/g, which is about 3 times of that observed in rGO-c (~5×10-3 emu/g). The noticeable difference in the MS is suggested due to the different concentration of oxygen-functional groups and other defects presented in the rGO sheets. The samples have similar structure and contains similar functional groups, yet rGO-s contains higher concentration of oxygen-functional groups and defects than rGO-c. A paramagnetic behavior was also indicated at low temperature. This study supports an indication of the defect-induced-magnetism in rGO and confirms that various magnetic features, such as ferromagnetic, diamagnetic and paramagnetic, can coexist in rGO.
Cu-Ni alloys are promising catalysts for precisely controlling the number of graphene layers grown by chemical vapor deposition (CVD). However, the theoretical understanding of the effect of the Ni atomic...
Electrical dan magnetic properties of graphene-derivatives materials are strongly influenced by their physical properties. Here we report a study on physical properties of reduced graphene oxide (rGO) prepared from two different raw materials, namely coconut shell (rGO-s) and graphite mineral (rGO-c, produced by Graphenea Inc.). rGO-s was prepared by carbonization method followed by mechanical exfoliation. While both samples have the same density of about 1.9 g/cm 3 , rGO-c has more porous compared to rGO-s. Specific surface area in rGO-c was also obtained much larger than that of rGO-s. Examinations on particle size and surface morphology show that rGO-c has homogenous particles which consist of transparent thin sheets, while rGO-s has rather heterogenous particles that look like dens stacked sheets. The presence of C and O was confirmed at the observed morphology. The difference in physical features was found to influence the obtained electrical conductivity of the samples. rGO-c has higher conductivity than rGO-s. Estimation on gap energy (Eg) indicates that rGO-c and rGO-s have Eg in the range of semiconducting materials. The study provides a better understanding on physical properties of coconut shell-derived rGO to further revise synthesis method to improve quality of the obtained rGO.
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