Graphene-based triboelectric nanogenerators for energy-harvesting applications

The paper reviews the use of graphene-based sensors for energy-harvesting applications. In the current era of exponential urbanization, scientists are trying to develop efficient devices to deal with the constant power shortage. Energy-harvesting has been one of the critical areas where micro-devices in the form of nanogenerators have been devised to generate and harvest energy. These devices have been capable of inducing a high range of open-circuit voltage, short-circuit current and power density. Graphene has been the most pivotal element in the nanomaterial spectrum to form sensing prototypes. It has shown high potential in the application spectrum as compared to its carbon counterparts due to its excellent electromechanical characteristics. It has been conjugated with various types of nanomaterials and polymers to develop a wide range of energy harvesters. This paper provides a substantial overview of the use of graphene in TENG devices. A classification has been shown here to exhibit the functionality of graphene as a structural form and processed material. While the structural layering includes graphene as the electrode and triboelectric layer, the processed material shows its amalgamation with metal oxides, polymers and other dopants to form composite-based energy harvesters. The existing challenges with the current graphene-based TENG devices are also displayed, along with possible remedies.