Table 1. Characteristics of the studied metal oxide nanoparticles.

Compound	Primary size1 (nm)Mean ± SD	Characteristics a	Specific surface area b (m2/g)	Density b (g/cm3)	Surface elemental composition b	Producer
ZnO_1	13.2 ± 5.4	Monodisperse, aggregated	26.2	5.6	16.9% C, 50.9% O, 32.2% Zn	PlasmaChem
ZnO_2	36.1 ± 18.1	Polydisperse	21.9	5.6	20.7% C, 43.8% O, 35.5% Zn	Degussa-Quimidroga
TiO2	10.0 ± 3.6	Aggregated	173.1	4.2	21.5% C, 42.2% O, 36.3% Ti	PlasmaChem
Al2O3	13.6 ± 8.4	Polydisperse	76.3	4.0	5.5% C, 46.1% O, 48.4% Al	PlasmaChem, Berlin
CeO2	13.0 ± 12.1	Polydisperse	56.7	7.2	22.1% C, 60.8% O, 17.0% Ce	Evonik-Degussa

^aData from Pérez-Campaña et al. (2012,2013).

^bData from Levin et al. (2015)