Bio-Nanocomposites for Sustainable Energy Technologies: Linking Green Synthesis, Interfacial Engineering and Device Performance

Abstract

The transition toward sustainable energy technologies requires advanced materials that can simultaneously deliver high functional performance, resource efficiency, environmental compatibility, and scalable processing. Bio-nanocomposites, formed by integrating bio-based polymers, biomass-derived materials, or biologically sourced components with nanoscale functional materials, have emerged as promising platforms for addressing these requirements. Their tunable surface chemistry, hierarchical structures, renewable feedstock availability, and nanoscale interfaces provide opportunities for applications in electrochemical energy storage, energy conversion, and emerging flexible energy technologies. However, the use of a renewable precursor does not inherently ensure overall sustainability, while excellent material-level electrochemical performance does not necessarily translate into practical device-level performance. This review critically examines the relationships among green synthesis pathways, sophisticated interfacial engineering, and the resulting performance in diverse energy devices including solar cells, batteries, supercapacitors, and fuel cells. Key findings highlight that biopolymers such as cellulose, chitosan, and lignin, when derived from agricultural waste or biogenic sources, provide sustainable alternatives to petroleum-based polymers. Interfacial engineering strategies, such as the construction of 3D ion transport channels and the use of biomimetic membranes, significantly enhance charge and ion transport kinetics. These advancements have led to superior device metrics, including area energy densities exceeding 53.5 mWh cm⁻² in flexible supercapacitors and over 89.21% conversion efficiency in biocatalytic energy processes. Despite these successes, challenges remain regarding the scalability of green extraction methods and the full mechanistic understanding of bio-synthetic interfaces. This report concludes that bio-nanocomposites represent a viable, eco-friendly pathway for achieving high-performance, circular energy solutions by establishing a direct relationship between green synthesis, interfacial chemistry, structure–property relationships, device performance, and sustainability.