A nanogenerator review of current trends, advancement and future directions

Abstract Nanogenerators are significant in the era of the emerging biodegradable energy harvesting systems, Internet of Things (IoT) application and wearable gadgets, where battery replacement and external power supply are challenging. The rise in energy demand coupled with concerns regarding environmental contamination caused by fossil fuel-based energy generation has spurred research and development of novel sustainable methods for energy harvesting. Nanogenerators increase the operational life of IoT devices by providing sustainable power source. Various nanogenerators like the piezoelectric nanogenerator, triboelectric nanogenerator, thermoelectric nanogenerator, pyroelectric nanogenerator and hybrid nanogenerator are used for sophisticated detection of systems in various fields that are small, inexpensive and environmentally benign. Generally, the choice of a nanogenerator depends on its intended application and the environment in which it will operate. Due to high output and different applications in different conditions and frequency ranges, triboelectric nanogenerators are extensively investigated. Piezoelectric nanogenerators have properties that are well-suited for wearable electronics and environmental sensing. Various studies have reported nanogenerators with high open-circuit voltages of 18 kV, 10 kV, 753 V and 578 V. and short-circuit currents of 348, 320 and 63.3 μA. Nanogenerator also have high operational lifetimes of 3,960,000, 1,260,000, 860,000 and 90,000 cycles. This review presents a comprehensive analysis of the state-of-the-art in green energy technologies focusing on the cutting-edge advancements in nanogenerator principles, simulations, material selection and applications in the emerging field of nanoscale energy conversion.