An Overview: Applying Diverse Plant-Based Methods for the Sustainable Synthesis of Titanium Oxide Nanoparticles and Their Environmental Application

The green synthesis of titanium dioxide (TiO₂) nanoparticles using plant extracts offers a sustainable alternative to conventional chemical and physical methods, addressing challenges in cost, toxicity, and scalability. While significant advancements have been made, further research is needed to optimize reaction parameters and understand plant biomolecule functions to facilitate large-scale applications. Among green synthesis approaches, plant-mediated methods stand out for their eco-friendliness, affordability, and efficiency. This review explores recent developments in plant extract-mediated TiO₂ nanoparticle synthesis, focusing on reaction mechanisms and key experimental factors such as precursor concentration, pH, temperature, and reaction time. Controlling particle size and morphology remains a critical challenge, influencing their photocatalytic performance. Compared to other green methodologies, plant-based synthesis demonstrates environmental benefits, lower production costs, and minimal hazardous waste. Typically, biosynthesized TiO₂ nanoparticles range from 2 to 70 nm in size, with a bandgap of 3.0–3.2 eV, making them effective photocatalysts. Studies have reported degradation efficiencies of 92% for methylene blue and 91% for methyl orange within 120–180 minutes under UV-visible light. This review identifies existing knowledge gaps and proposes strategies to enhance TiO₂ nanoparticles synthesis for improved photocatalytic applications. Moreover, it highlights their potential in environmental remediation, sensing, and emerging industrial and biomedical fields. By systematically evaluating plant-mediated synthesis, this study aims to advance commercially viable, sustainable, and scalable green synthesis methods that ensure both environmental safety and industrial feasibility.