Titanium dioxide (TiO2) and silver (Ag) nanoparticles have applications in photo catalysis and antimicrobial uses. TiO2 nanoparticles effectively degrade organic pollutants in water when exposed to light, and nano-sized TiO2 shows high photocatalytic activity. Ag nanoparticles also exhibit strong antimicrobial properties and are commonly used for their ability to treat microbes. These metal oxide nanoparticles can be synthesized through various methods like sol-gel processing, chemical vapor deposition, and hydrothermal synthesis. When doped together in materials like AgTiO2, they show enhanced photocatalytic and antibacterial activity under visible light.