Sustainable Water Purification Using Green‐Synthesized Nanoparticles: A Comparison Between Mono‐ and Bimetallic Nanoparticle Systems

ABSTRACT This review explores recent advancements in using environmentally benign monometallic nanoparticles (MMNPs) and bimetallic nanoparticles (BMNPs) for photocatalytic water purification, addressing the urgent need for sustainable solutions to global water scarcity. This study systematically analyzes how key photocatalysis variables, including nanocatalyst concentration, dye selection, and pollutant concentration, influence dye degradation outcomes. Standardized experimental conditions utilizing UV irradiation, 10 ppm, methylene blue (MB), and green synthesis routes were employed for comparative assessment. Results indicate that BMNPs, particularly Ag‐Cu BMNPs composites, consistently outperform their MMNPs, achieving degradation rates between 90% and 99%, compared to 70%–85% for MMNPs. This superior performance is attributed to synergistic effects between the constituent metals. The review further highlights the advantages of plant‐based synthesis methods, which offer a safer, more economical, and stable alternative to conventional chemical methods. By critically evaluating the potential of these NPs under controlled scenarios, this work underscores the transformative potential of engineering BMNPs in advancing next‐generation water treatment technologies.