The effectiveness of a photocatalyst under visible light depends on its ability to absorb light in the visible range (400-700 nm) and generate charge carriers (electrons and holes) that can drive chemical reactions. This is largely determined by the photocatalyst's bandgap, which should ideally be less than 3.1 eV. Materials like titanium dioxide (TiO2) and zinc oxide (ZnO) are commonly used photocatalysts but are limited by their large bandgaps, making them active primarily under UV light.
