Photoactive Widegap Oxide Doped ZnO with Non-stoichiometric Matrix: Aspects of Formation

XRD, ESR, TRMC and UV–visible spectroscopy are used for the description of characteristics of investigated systems and determination of forming structure mechanism in Al, Zr or Ce doped non-stoichiometric ZnO_1−x. It was shown the Al and Zr ions substitute the lattice Zn²⁺ in the ZnO matrix, and as a result, the donor's levels form in ZnO bandgap and acceptor’s level of zinc vacancy. Last level is a trap of phogenerate holes in material and it allows to delay photocatalytic actvity Al- and Zr-doped ZnO. Ce ions incorporate as interstiallite ions or segregate on crystal surface that leads to appearance the f-levels in the bandgap of ZnO, and as a result, the cerium ion will trap for electron. It decreases electron lifetime or increases of hole lifetime and also if cerium ion segregates on the ZnO surface the set of reactions (Ce⁴⁺ + e- = Ce³⁺, Ce³⁺ + O₂ = Ce⁴⁺ + O₂⁻) may occur. It leads to form additional reactive oxygen species, in particular, super-anion radicals (O₂⁻, ROS) that improve the activity of the material. As a result, the increasing of phenol degradation by 30% compared to pure ZnO may be achieved at the choice of Ce-doped ZnO catalyst.