A Review on Triboelectric Nanogenerators, Recent Applications, and Challenges

Triboelectric nanogenerators (TENGs) have special characteristics that can boost the Internet of Things (IoT) development in various industries toward realizing a smart world. Herein, first, the history of TENGs and their applications are discussed. Then, the unique characteristics and positive attributes of TENG that differentiate it from other generators and nanogenerators are elucidated based on the working mode and application, with a focus on the role of TENGs in supporting renewable energy. Triboelectrification occurs due to the interatomic interactions between the surfaces with relative movements. Since triboelectrification can occur between any two materials at different triboelectric series, it results in a highly cost-effective and eco-friendly energy harvesting method. Hence, TENGs can be applied multifariously, ranging from at the nanoscale in highly sensitive self-powered sensors to a large scale for obtaining the dissipated daily energy of the ocean or signals in harsh environmental conditions. Triboelectrification mechanism based on interatomic interactions and other important parameters is discussed. Additionally, the efficiency of TENG, including the mechanical performance of the system and triboelectrification phenomenon, from both energy harvesting and energy transfer systems, together with the vital influential parameter of surface charge density is illustrated. Consequently, main feature of TENG is illustrated to give a significant view to the TENG researchers to select an appropriate working mode of the TENG based on the application, working conditions, and unique characteristics. Finally, the vital challenges of TENGs are discussed to broaden its scope of research, enhance its applicability performance in the direction of the smart world.