This work aims to develop and characterize graphene oxide (GO) and glass fiber (GF)-based hybrid epoxy composites. Graphite oxide was synthesized by improved Hummers' method, and it was uniformly dispersed in ethanol by ultra-sonication to form GO suspension. Later, GO and GF-based hybrid epoxy composites were prepared by hand layup method followed by curing under compression to develop composite sheets accordingly to the ASTM standards (D3039 & D6110-18). Fourier transform infrared spectra of the neat and the GF-based hybrid epoxy composites confirmed the formation of improved interface between GO/epoxy and silane coating present on GF surface, which is well validated with the given reaction schematic. Scanning electron microscope and elemental mapping results corroborate our point that the GO filled the voids and empty spaces and lessened the water absorption properties of the composite which is much needed for the application of composites at high altitudes and marine environment. Effect of GO content on mechanical properties of prepared composites was studied by varying the GO content from 0.1 to 1.2 wt%. Mechanical characterization of GO and GF-based hybrid epoxy composites were carried out by tensile and impact testing. Ultimate tensile strength,
Clinical applications of bio-absorbable magnesium (Mg) and its alloys can be enhanced by increasing their corrosion resistance, using surface modification and functionality. In this study, we synthesized graphene oxide (GO) through improved Hummers’ method and deposited it on biodegradable AZ31B Mg alloy for further characterization. Different suspensions of GO were prepared in various solvents, like deionized water, ethanol, and acetone by ultra-sonication. Electrophoretic deposition (EPD) was used to develop GO coatings on AZ31B Mg using different GO suspensions. Effect of various solvents on corrosion behavior, as well as in vitro biocompatibility, was studied. The optimized EPD parameters were 3 volts and 90 s for coating. Different characterization techniques were used to study GO and prepared coatings. Atomic force microscopy found that the average thickness of GO was ~1 nm. Electrochemical behavior of coatings was studied through electrochemical impedance spectroscopy (EIS) and Tafel analysis in Ringer’s lactate solution. Tafel analysis revealed that GO coatings deposited by GO water suspension increased corrosion protection efficiency of AZ31B Mg alloy by ~94%. After 72 h incubation in MC3T3-E1 osteoblast cells extract, in vitro analysis was performed to determine the cell viability and biocompatibility of the GO- coated and bare Mg samples. GO coatings deposited by GO water suspension demonstrated ~2× cell viability, as well as nontoxicity and better biocompatibility compared to the bare and other GO-coated Mg samples.
We explored the potential of heteroatom-doped graphene oxide (GO)-based electrodes for energy storage. Binder-free electrodes were synthesized using the hydrothermal method, where doping of GO and its electrode development was achieved simultaneously in one step. GO was doped with nitrogen (NGO) and boron (BGO) using urea and boric acid as nitrogen (N) and boron (B) sources, respectively. In addition, GO was also co-doped with B and N (BNGO). The atomic percentages of nitrogen and boron in NGO and BGO were found out to be 6.13% and 17.94%, respectively, as revealed by XPS. The BNGO had atomic percentages of boron and nitrogen as 23.76% and 3.64%, respectively. Electrodes were electrochemically characterized in 3 M KOH electrolyte by employing cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD). CV analysis revealed that NGO and BNGO exhibited superior charge storage capacity with a high specific capacitance of 855 and 811 F g À1 , respectively, at 1 m Vs À1 . CV data were further analyzed to identify and quantify charge storage mechanism, and it suggested that binder-free-doped electrodes exhibited diffusioncontrolled charge storage as dominant behavior. Thus, our results demonstrate an approach to dope GO and develop high-performance, binder-free electrodes for supercapacitor applications in a facile single-step hydrothermal method.
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