Instead, a progressive energy blue-shift takes place for ZSO-7.7
(Eg = 3.38 eV) and ZSO-4.0 (Eg = 3.55 eV) [30,31] due to the smaller
ZnO NPs dimension (the absorption edge lines in Fig. 2 have been
split to draw the tangents and calculate the band gap energy). In
order to study the interaction between ZnO particles and SiO2
and aiming to point out the SiAOAZn bond formation, solid state
29Si SP MAS, 29Si CP MAS and 1H MAS NMR investigations were
performed on ZSO-X samples.