 This study reviews recent research on titanium dioxide, TiO2-based photocatalysts for environmental applications, highlighting their exceptional physical chemical properties and limitations due to a narrow band near the ultraviolet region. The study discusses strategies to improve visible light sensitivity through modifications of TiO2's optical and electronic properties, as well as nanotechnology to enhance its properties in an environmentally friendly way for pollutant degradation in air, water, and wastewater treatment under visible light.