From Conventional to Modern Synthesis: A Comparative Review of Monometallic and Bimetallic Nanoparticles

Nanoparticles have been explored for centuries, offering remarkable properties and wide-ranging applications. Among these monometallic nanoparticles have demonstrated significant potential in diverse scientific and industrial applications. They are proven to be highly useful due to their distinct physical, chemical, and biological attributes. However, recent advancements have shown that combining two different metals forms bimetallic nanoparticles. These have enhanced capabilities- improving stability, catalytic efficiency, selectivity, and multifunctionality beyond the limits of single-metal systems (for example, bimetallic Au-Pd catalyst show 4-5 fold increase for benzyl alcohol oxidation, compared to monometallic Pd, and NiCo system showing a 3 fold increase in hydrogen storage evolution (HER) reaction compared to monometallic Ni). This change marks a significant leap from traditional monometallic to next-generation bimetallic systems. However, these advancements come with increased complexity in design, synthesis, and characterization techniques. This review traces the evolution of nanoparticles from their historical origins, with emphasis on monometallic and bimetallic systems, highlighting their respective advantage, challenges and technological implications. It further explores how green synthesis approaches are revolutionizing the fabrication of nanoparticles for applications across medicine (genetics, molecular biology, medicine, dentistry) and engineering. By integrating historical context with contemporary developments, this manuscript provides a comprehensive perspective on how these green synthesized nanoparticles are shaping the future of nanotechnology.