**4. Applications of improved nanocomposites**

Applications of improved carbon nanocomposites are shown schematically in **Figure 4***.*

#### **4.1 Energy storage**

Currently, Graphene materials find a number of applications in the field of renewable energy, particularly photoenergy field, including solar thermal conversion, solar electricity conversion, photocatalysis, etc. New technologies related to solar cells have been developed in which either the active medium or transparent/ distributed electrode consists of Graphene materials. A newly developed 3D crosslinked graphene material working as an ideal solar thermal converter can obtain the efficiency of 80% and more than 80% under one sun intensity and the ambient sunlight respectively [69]. The structural design possessed by the material plays a significant role in improving the efficiency of energy conversion. The unique structure of graphene foam due to an array on its 3D skeleton, created by nanoplates of the graphene, provides a greater area for heat exchange. This enhances the efficiency of solar-thermal conversion up to 93.4%. Dye-sensitized solar cells (DSSC) consisting of a redox couple and a counter electrode are used extensively for solarelectrical energy conversion [70]. Dye-sensitized solar cells (DSSCs) composed of coloring molecules, natural liquid electrolytes, and nanocrystalline metal oxides

*Improved Nanocomposite Materials and Their Applications DOI: http://dx.doi.org/10.5772/intechopen.102538*

#### **Figure 4.**

*Applications of improved carbon nanocomposites.*

have shown greater performance in energy conversion and manufacturing costs and low energy. Nowadays, graphene-based electrodes exhibiting chemical stability and good conductivity, very large surface area, considerable high porosity, and electrocatalytic activity are used in DSSC. The application of this electrode led to the improvement in the performance and the reduction of the cast to a large extent. A super-capacitor designed by Stroller et al. [71] from the chemical modification of graphene material exhibited specific capacitance 135 F/g, 99 F/g, and 99 F/g in aqueous electrolytes, ionic electrolytes, and organic electrolytes respectively. High life cycle and high power have been shown by these types of storage devices. Zhang et al. [72] synthesized a useful stretchable electrode by the mechanical exfoliation of graphene prior to chemical treatment. These electrodes show high flexibility and compatibility in usage in various electrolytes. Moreover, graphene conducting polymer composites or graphene transition metal composites can be used to devise Super-capacitors.

#### **4.2 Antimicrobial activity**

Graphene nanomaterials possess intrinsic antimicrobial properties and also act as a platform to design antimicrobial nanocomposites having higher antimicrobial activity. Graphene is an ideal scaffold material owing to its huge surface area to anchor various sorts of macromolecules and nanoparticles. The attachment of diverse compounds such as quaternary phosphonium salts to graphene has greatly improved the antimicrobial properties. Researchers have shown great interest in Silver owing to its higher antimicrobial activity and studied it extensively to design graphenebased antimicrobial nanocomposites. In this section, the research carried out on the development of graphene–silver antimicrobial nanocomposites will be discussed. As the nanocomposites possess greater antimicrobial activity, graphene–silver nanocomposite is preferred over silver nanoparticles alone. Graphene–silver nanocomposites facilitate the leached silver ions from the nanoparticles to penetrate the cell owing to graphene which possesses the property to rupture a cell membrane. The purpose of this proposed mechanism was to explain the synergetic effect caused by silver and graphene existing together in the form of nanocomposite, and proteomic analysis of this effect of graphene–silver nanocomposites compared to silver nanoparticles alone [73] supported the mechanism as well.
