Emerging insights into the piezoelectric properties of cellulose: From macro to nanoscale structures

Nowadays, the increasing demand for sustainable energy has brought piezoelectric materials to the forefront due to their capability to convert mechanical energy into electrical energy. In response to increasing environmental concerns, cellulose has emerged as a promising piezoelectric material, owing to its availability, biocompatibility, sustainability, biodegradability and cost-effectiveness. Despite significant research on the use of various forms of cellulose for piezoelectric energy harvesting, a systematic review focusing on the factors that can affect the piezoelectric property in cellulose remains notably absent. The main goal of this review is to fill this gap by understanding the piezoelectric behaviour of cellulose at different hierarchical levels, from macro-scale natural materials to nano-scale structures. This review presents an overview of the general aspects of the piezoelectric effect, followed by a detailed examination of the piezoelectric properties of cellulose. It further explores the piezoelectric behaviour of cellulose-based natural materials. The review then addresses the piezoelectric characteristics of nanocellulose and regenerated cellulose in turn. Furthermore, the review examines cellulose-based hybrid materials and their piezoelectric properties. In conclusion, the review highlights the current challenges and outlines promising directions for future research in this emerging area.