Applications of Graphene in Improving Mechanical and Energy Conversion Materials

Since it was confirmed to exist in 2004, graphene has become a popular material for numerous researchers to study. The worldwide enthusiasm for this novel material is as yet expanding currently, as it can be envisaged from the number of patents, publications and a substantial amount of capital. The reason why graphene is so attractive is that it has nearly perfect performance in all aspects, such as mechanic, thermal, optic, and electric. So that it can be applied to solve certain technical problems and provide convenience for human life.

This report consists of two parts, respectively introducing the application of graphene in enhancing the mechanical strength of other materials and accelerating the speed of evaporation to improve the global issue of water.

In the first part, polyethylene (PE) films reinforced with graphene processed using self-build fabrication platform are shown to have outstanding mechanical properties. The values of specific ultimate tensile strength and Young’s modulus of PE/graphene films represent the highest reported to date for other composite materials. The experimental characterizations indicate that during the films processing, graphene fillers are exfoliated, which is further confirmed by molecular dynamics simulations. Exfoliation increases the specific area of the graphene fillers in contact with PE matrix molecules. Molecular dynamics simulations show that the PE-graphene interaction is stronger than PE-PE intermolecular van der Waals interaction, which enhances load transfer from PE to graphene and leverages the ultrahigh mechanical properties of graphene. Other properties of fabricated film are discussed as well.

For the second part, it is demonstrated that the functionalized graphene using hydrophilic groups can greatly enhance the solar steam generation efficiency. The related experiments show that such an improvement is a surface effect mainly attributed to the more hydrophilic feature of functionalized graphene, which influences the water meniscus profile at the vapor-liquid interface due to capillary effect. This strategy of functionalizing graphene to make it more hydrophilic can be potentially integrated with the existing macroscopic heat isolation strategies to further improve the overall solar-to-vapor conversion efficiency.