Table 2.

Photocatalytic activity of various ZnO composites.

Catalyst Composite	Method of Synthesis	Light Used for Irradiation	Irradiation Time (min)	Photo-Degradation (%)	Refs.
ZnO nano-needles on Si substrates	Hydrothermal	UV light	140	95.4	[48]
ZnO quantum dots	Flame spray pyrolysis	UV light	160	97	[49]
TiO2/biochar	Hydrolysis	UV light	160	96.88	[17]
Xanthan gum/TiO2	Hydro-gel	Visible light	90	89	[15]
Anatase TiO2	Sol-gel	Visible light	240	67.12	[50]
ZnO catalyst	Hydrothermal	UV light	180	99.7	[51]
Rare earth metal doped ZnO	Sol-gel	UV light	180	98	[32]
ZnO.SiO2	Co-precipitation	UV light	100	98.1	Present work