Algae and Fungal Assisted Nanoparticle Synthesis and Their Applications in Energy Storage and Photocatalysis

The growing demand for sustainable nanomaterials has driven significant interest in biologically mediated synthesis routes, particularly those employing algae and fungi. These organisms provide an eco-friendly, cost-effective, and scalable alternative to conventional physicochemical methods for nanoparticle production. Algae and fungi possess diverse biomolecules—including proteins, polysaccharides, enzymes, and secondary metabolites—that act as reducing, stabilizing, and capping agents, enabling controlled nanoparticle synthesis. This review critically examines recent advances in algae- and fungal-assisted nanoparticle synthesis, focusing on synthesis mechanisms, physicochemical characteristics, and process optimization. Furthermore, it highlights the functional applications of these biogenic nanoparticles in energy storage systems such as supercapacitors, batteries, and hydrogen production, as well as in photocatalytic degradation of environmental pollutants. The role of nanoparticle morphology, surface chemistry, and bandgap engineering in enhancing photocatalytic and electrochemical performance is discussed in detail. Despite their advantages, challenges related to scalability, reproducibility, and long-term stability remain. Future research directions emphasize the integration of bio-assisted nanomaterials into hybrid systems, development of green synthesis protocols for industrial-scale production, and exploration of novel algal and fungal species. This review provides a comprehensive understanding of the potential of algae and fungi as biofactories for advanced nanomaterials, paving the way for sustainable energy and environmental technologies.