Different kinds of Co₃O₄ made using multiple methods of synthesis are used for degradation of dyes.

S. no.	Photocatalyst	Catalyst amount (mg)	Pollutant	Dye conc. (mg L−1)	Degradation (%)	Time (min)	Rate constant K (min−1)	Synthesis method	Light source	References
1.	Co3O4/TiO2 nanocomposite	1000	Ciprofloxacin (CIP)	10	100	60	0.0157	Sol–gel approach	Visible	22
2.	p–n Co3O4–TiO2 heterojunction	1000	Methyl orange	100	88	120	0.0097	Wet incipient impregnation method	Ordinary visible light	13
3.	Co3O4–TiO2 nanoparticles	50	Tetracycline (TC) and phenol (Pl)	—	TC = 67.4, Pl = 85.6	180	TC = 0.01794, Pl = 0.01975	Sol–gel technique	Sunlight	59
4.	Co3O4–TiO2 nanohybrid	50	Methyl orange (MO)	10	76	300	0.28	Sol–gel methodology	Solar	60
5.	Co3O4/TiO2 nanorod arrays	—	Methylene blue	10	MB = 60	530	0.91745	Photochemical deposition method	500 W Xe lamp	61
6.	rGO-TiO2/Co3O4 nanocomposite	50	Methylene blue and crystal violet	10	—	120	—	Co-precipitation method	150 W tungsten lamp (with main wavelength at 465 nm)	62
7.	0D/2D Co3O4/TiO2 Z-scheme heterojunction	20	Enrofloxacin	20	95.6	100	0.0269	Hydrothermal method	500 W xenon lamp light source	63
8.	p-Co3O4/n-TiO2 nanopine arrays	—	Tetracycline hydrochloride (TC)	—	200	60	—	Hydrothermal method	Visible light	64
9.	Co3O4/TiO2 nanotube arrays (NTs)	—	Methyl orange (MO)	4 × 10−5 M	92	90	0.027	Impregnating–deposition–decomposition method	50 W xenon lamp	65
10.	p–n heterojunction (Co3O4/TiO2)	—	Acetaminophen (ACE)	—	96.78	10	—	—	Simulate solar light illumination	66
11.	Co 3 O 4 /TiO 2 nanocomposite	25	OR	25	83	6	0.2958	Hydrothermal	Sunlight	Present work