Representative iron oxide nanozymes obtained through sol–gel procedures.

Variable/technique	Starting materials	Solvent	Particle size (nm)	Morphology	Additional property	Ref.
Agitation time	Fe (NO3)3·9H2O	Absolute ethanol	10 nm	Spherically	Purity > 75%	75
	Ba (NO3)2
Carbonization method	FeCl3·6H2O/rosin	Deoxygenated H2O/ethanol	<50 nm	Varies with different rosins: FeCl3	Enhances interfacial reactivity	76
Non-hydrolytic	Anhydrous FeCl3	Anhydrous ethanol	202–373 Å	Rod-shaped	Homogeneous dispersion	77