Recent advances of triboelectric, piezoelectric and pyroelectric nanogenerators

Nanogenerators are widely used in harvesting and converting mechanical or thermal energy into electric energy. It is a promising way to capture energy from the surrounding environment as portable power supplies and self-powered systems, offering great versatility and feasibility. Current studies focus on designing nanogenerator structures and materials with high power outputs, multifunctionality and low-cost characteristics. In this review, we will introduce the technological advances of three common nanogenerators, namely, triboelectric, piezoelectric and pyroelectric nanogenerators. The fundamental components, including the working mechanism, structure design, materials selection and main applications, are compared and systematically discussed. Current challenges and future perspectives are highlighted with a focus on offering new insights into developing the next generation nanogenerators that are highly integrated, multifunctional and of upgraded performance.