Graphene Oxides (GO) typically contains different oxygen containing groups such as hydroxyl, carboxyl and epoxy, and reduced GO (r-GO) represents a family of material with diverse chemical properties. In an effort to understand how properties of r-GO change as GO is reduced, a stepwise reduction of the same GO to r-GO containing different levels of oxygen was carried out, and their corresponding chemical and colloidal properties are reported. Starting with GO containing 49 percent oxygen, r-GOs containing 31, 19 and 9 percent oxygen were synthesized. The aqueous behavior in terms of solubility gradually decreased from 7.4 µg/ml for GO to nearly zero for r-GO with 9% oxygen, while dispersibility under sonication decreased from 8 to 2.5 µg/ml for the same samples. Hydrophobicity index as measured as the octanol water partition coefficient decreased from −3.89 to 5.2% as oxygen content dropped from 49 to 9%. Colloidal behavior was also dramatically affected by reduction, and critical coagulation concentration (CCC) dropped from 28 to 15 in presence of 0.5 mmole/l NaCl and from 6 to 2 in presence of 0.5 mmole/l MgCl2 as the oxygen in the original GO was reduced to 9%.

Top and bottom microelectrode glass slide sandwiches a channel made of adhesive tape and packed with reduced graphene oxide to make a new non-planar interdigitated microfluidic device. Novel device integration allows packing of any transducer material at room temperature with no instrument. Electrical impedance spectroscopy signal is stable over long times, fits an equivalent circuit with well-defined circuit elements. Flow visualization concurs that electric double-layer signal shifts to high frequency due to disruption of the diffusive process from increased convective flow. Charge transfer resistance appears at higher frequencies making the device rapid with high signal to noise ratio.

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Novel polyacrylamide gel electrolytes (PGEs) doped with nano carbons with enhanced electrochemical, thermal, and mechanical properties are presented. Carboxylated carbon nanotubes (fCNTs), graphene oxide sheets (GO), and the hybrid of fCNT/GO were embedded in the PGEs to serve as supercapacitor (SC) electrolytes. Thermal stability of the unmodified PGE increased with the addition of the nano carbons which led to lower capacitance degradation and longer cycling life of the SCs. The fCNT/GO-PGE showed the best thermal stability, which was 50% higher than original PGE. Viscoelastic properties of PGEs were also improved with the incorporation of GO and fCNT/GO. Oxygen-containing functional groups in GO and fCNT/GO hydrogen bonded with the polymer chains and improved the elasticity of PGEs. The fCNT-PGE demonstrated a slightly lower viscous strain uninform distribution of CNTs in the polymer matrix and the defects formed within. Furthermore, ion diffusion between GO layers was enhanced in fCNT/GO-PGE because fCNT decreased the aggregation of GO sheets and improved the ion channels, increasing the gel ionic conductivity from 41 to 132 mS cm−1. Finally, MnO2-based supercapacitors using PGE, fCNT-PGE, GO-PGE, and fCNT/GO-PGE electrolytes were fabricated with the electrode-specific capacitance measured to be 39.5, 65.5, 77.6, and 83.3 F·g−1, respectively. This research demonstrates the effectiveness of nano carbons as dopants in polymer gel electrolytes for property enhancements.

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This article presents the first report on systematic synthesis and evaluation of activated carbons from the cap and stalk of two diverse mushroom species namely, Ganoderma lucidum (GL) and Calocybe indica (CI) belonging to different classes white rot and brown rot respectively. A novel microwave induced H3PO4 activation followed by carbonization and KOH activation enabled the formation of activated carbon with hierarchical structures. The activated carbons from cap and the stalk of the mushrooms are different in terms of specific surface area, pore volume, and their electrochemical behavior. Specific surface area and pore volume from GL‐cap is as high as 2432.4 m2/g and 0.54 CC/g, respectively. After optimization, the activated carbons have high graphitic content, good thermal stability and show specific capacitance as high as 271.94 F/g, energy and power densities of 13.59 Wh/kg and 127.31 W/kg, respectively. All the carbons show good capacitance retention up to 10 000 cycles. The surface area and specific capacitance in the mushroom stalks are lower than the ones made from the caps and the highest surface area and specific capacitance are 1576.2 m2/g and 137.2 F/g respectively for GL‐stalk.