2D hybrid and biodegradable piezoelectric nanogenerators for self-powered systems: Next generation sustainable energy

The growing global demand for sustainable and portable energy solutions has fueled research into nanogenerators (NGs), primarily those leveraging piezoelectric effects for energy harvesting. The increasing demand for biodegradable (BD), biocompatible, wearable, and flexible electronics has driven the development of advanced NGs, capable of converting mechanical, frictional, or thermal energy into electrical power. Piezoelectric NGs (PENGs), utilizing 2D hybrid (HD) and BD components, offer a promising path towards next-generation self-powered devices combining high-performance energy harvesting systems with environmental sustainability, making them ideal for innovative and eco-friendly electronics. Compared to traditional materials, 2D HD offers atomic-scale thickness, high mechanical strength, and intrinsic piezoelectric properties at the monolayer level. Integration of 2D HD with BD substrates enables the fabrication of fully degradable, biocompatible, and flexible/non-flexible devices capable of harvesting energy from mechanical motions, such as vibrations, bending, or body movement. This review highlights the latest developments in 2D HD and BD materials for flexible/non-flexible PENGs, focusing on their design, working principles, and application in real-time sensing and self-powered electronics. Special emphasis is given to material innovations, structural configurations, and the role of biodegradability in enhancing device sustainability. Current challenges and prospects are also discussed for scalable and reliable BD-based self-powered systems tailored for next-generation sustainable energy technologies. • Current state-of-the-art of 2D HD and BD materials-based NGs as energy harvesters. • Design, mechanism, stability, and performance of 2D HD and BD PENGs. • PENGs for self-powered systems, including electronics, biomedical, and remote sensing. • BD PENGs, TENGs, ThNGs, PyNGs for zero emissions.