Visible-light-active ZnO Via Oxygen Vacancy Manipulation For Efficient Formaldehyde Photodegradation

Formaldehyde is one kind of common raw materials which be used in a lot of industry fields, such as medical industry, resin preparation,textile, dye preparation and thermal insulation materials. However, the formaldehyde has a serious influence on both human health and environment for its high toxicity. The photocatalytic degradation is an important method to solve this problem. Among the oxide semiconductor photocatalysts, Zn O is widely used in the photodegradation filed due to its high quantum conversion rate. However, ZnO can only response to the ultra-violet because its wide band gap. Thus making ZnO response to the visible light becomes more and more important. We developed a facile method to prepare ZnO which can response to the visible light and investigated its photocatalytic activity in formaldehyde degradation. The experiments results are posted below:(1) We use a facile method to prepare nano-ZnO with oxygen vacancy. XRD, TEM, HRTEM, SAED, Raman, FT-IR and UV-VIS were employed to investigate the ZnO samples. First principle theory was usedto investigate the relationship between the concentration of oxygen vacancy and wide of band gap of ZnO. It can be found that the oxygen vacancy on the surface of ZnO act as active site which can be used to capture oxygen-containing groups, besides, the band gap of ZnO narrowed with the increasing of oxygen vacancy concentration.(2) The relationship between the annealing temperature and the oxygen vacancy concentration and how the oxygen vacancy concentration affect the formaldehyde degradation were investigated. It was found that the degradation capacity of ZnO increased with the increasing of oxygen vacancy concentration. Furthermore, the role of oxygen vacancy in the formaldehyde photodegradation was briefly explained.