Nanogenerators is the growing technology that facilitates self-powered systems, sensors, and flexible and portable electronics in the thriving era of internet of things (IoT). Since the first invention of the triboelectric nanogenerators (TENGs) in 2012, it has become one of the most important inventions in energy harvesting technologies. In this paper, a brief review on the recent progress of energy harvesting research based on TENGs technology is discussed. Basic working modes of the TENG are discussed in detail and the general procedure to synthesize, measure, and characterize a nanogenerator is presented in a direct structure. The triboelectric material choices are extremely important for TENGs since the triboelectric effects of the materials are fundamental for TENGs. The materials used as triboelectric layers are varied from polymers, metals, and inorganic materials with the commonly used materials are dielectric polymers such as PTFE, PVDF, PDMS, nylon, and Kapton. Recently, two-dimensional (2D) materials have been widely reported as candidate materials for TENGs. Graphene, the most attractive 2D materials exhibits an excellent electrical property, great flexibility, and a high surface-to-volume ratio. Owing to the very low thickness of the atomic unit, a stacking graphene structure can be also made to form a very thin and miniature TENGs device. The major applications of the graphene as active materials for TENGs as a sustainable energy harvester are presented, following which structural designs and materials optimization for output performance improvement of the graphene-based TENGs are summarized. Finally, the future directions and perspectives of the graphene-based TENGs are outlined. The graphene-based TENGs is not only a sustainable micro-power source for small devices, but also serves as a potential macro-scale generator of power from blue energy in the future.

中文翻译：

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石墨烯在摩擦纳米发电机中的应用综述

纳米发电机是一种不断发展的技术，可在物联网 (IoT) 蓬勃发展的时代促进自供电系统、传感器以及灵活和便携式电子设备的发展。自 2012 年首次发明摩擦纳米发电机 (TENG) 以来，它已成为能量收集技术中最重要的发明之一。本文简要回顾了基于 TENGs 技术的能量收集研究的最新进展。详细讨论了 TENG 的基本工作模式，并以直接结构介绍了合成、测量和表征纳米发电机的一般程序。摩擦电材料的选择对于 TENG 来说非常重要，因为材料的摩擦电效应是 TENG 的基础。用作摩擦电层的材料有聚合物、金属、而无机材料常用的材料有PTFE、PVDF、PDMS、尼龙、Kapton等介电聚合物。最近，二维（2D）材料已被广泛报道为 TENG 的候选材料。石墨烯是最具吸引力的二维材料，具有优异的电性能、极大的柔韧性和高表面积体积比。由于原子单元的厚度非常低，堆叠的石墨烯结构也可以制成非常薄的微型TENGs器件。介绍了石墨烯作为 TENGs 活性材料作为可持续能量收集器的主要应用，然后总结了石墨烯基 TENGs 输出性能改进的结构设计和材料优化。最后，概述了基于石墨烯的 TENG 的未来方向和前景。基于石墨烯的 TENGs 不仅是小型设备的可持续微型电源，而且还可以作为未来蓝色能源的潜在宏观发电机。