Effect of Cu+ ions on the structure, morphology, optical and photocatalytic properties of nanostructured ZnO

Abstract

Solid solutions Zn1−xCuxO and/or hybrid materials Zn1−xCuxO/CuxO of the “core-shell” type were obtained by one-step thermolysis of Zn1−хCux(HCOO)(OCH2CH2O)1/2 complexes. Precursors the Zn1−хCux(HCOO)(OCH2CH2O)1/2 complexes were synthesized under solvothermal method from the corresponding formates and ethylene glycol. It was established that copper in these materials is a promoter of the photoactivity and morphology of aggregates. Zn1−xCuxO solid solutions (0 < x < 1) have 1D-morphology of aggregates, Zn1−xCuxO/CuxO hybrid materials are spherical. According to TEM, XPS, optical spectroscopy and voltammetry data, Cu+ prevails in the solid solution samples and its concentration increases with transition to hybrid materials. It was shown that solid solutions with tubular particle morphology exhibit the maximum photoactivity of As3+ in UV and blue light. The expansion of the spectral range of Zn1−xCuxO irradiation to the visible region is explained by the formation of acceptor levels (Cu2+ + e− → Cu+/VO+ + e− → VO) in the band gap of ZnO, which increases the efficiency of separation of photogenerated electron-hole pairs. The presence of Cu+ in the material intensify photoactivity due to the formation of an overactive oxygen radical O2−.