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Oxygen charge ion11/7/2023 Among the metal ions and oxides, Cu 2O is a nonstoichiometric p-type semiconductor with a direct forbidden bandgap of about 2.0 eV, whose component elements are inexpensive and abundantly available 15, 16. Therefore, in order to suppress the recombination of the electron and the hole and enhance the migration of charges, much attention has been focused on the modification of TiO 2 by adding metal ions or oxides 12, 13, 14. However, the recombination of the electron and the hole would happen, that is, the superoxide (O 2 −) is reduced. Then, the electron and hole react with water and oxygen, it would produce hydroxyl radicals ( For example, when TiO 2 semiconductor materials with the forbidden bandgap of 3.2 eV are irradiated by light consisting of wavelengths shorter than 415 nm, the electron-hole pairs are produced after the migration of electrons. ![]() When the semiconductor material absorbs photons with energy equal or larger than its band gap, electrons in the valence band can be excited and migrate to the conduction band. Semiconductor materials are materials whose valence band and conduction band are separated by an energy gap or band gap. So far, in most applications of photocatalyst, an n-type TiO 2 semiconductor has been used 9, 10, 11. At the same time, O 2 − production probably takes place under the natural conditions as a result of gas ionization in the atmosphere. In this paper, we adopt anion incentive method, which selected suitable photocatalyst irradiated by light to excite energy, and the excitation energy ionized the oxygen molecule to produce negative ions. Therefore, artificial method to achieve negative oxygen ions include UV irradiation, anion incentive, thermionic emission, corona discharge, charge separation, high-pressure water injection, tourmaline and other natural ores, and so on. At the same time, O 2 − production probably take place by surface ionization, which is identified as a viable ionization technique to have the potential to meet the requirements concerning ionization efficiency for the energy range of 10 eV to 1 keV within the limitations imposed by the resources (space, weight, powder, light, ect.) available on a proper surface 5. And the biological effects of superoxide (O 2 −) are considered in relation to the reactions leading to cell death and to the metabolism of certain endogenous compounds 8. The researchers have found that negative oxygen ions could combine with bacteria, dust, smoke and some other positively charged particles in the atmosphere, and fall to the ground after gathering into balls, which would lead to the sterilization and the elimination of peculiar smell, that is, a purification of atmosphere. Meanwhile, the effects of negative oxygen ions on human health and ecological environment have been validated by domestic and foreign medical experts through clinical practices 6, 7. The negative oxygen ions are also known as “air vitamin” due to its important meanings to human life activities. As the oxygen molecule captured an electron, the oxygen molecule is defined as negative oxygen ion (O 2 −) 4, 5. Especially after the mechanism of the action of negative oxygen ions and its effects have been increasingly understood, the negative oxygen ions products will be developed as a kind of functional products 1, 2, 3. Nowadays, with the development of social and economic and the improvement of living standards, the human health awareness is also growing. The wood modified with TiO 2/Cu 2O composite film after hydrophobization is imparted with superamphiphobicity, antibacterial actions against Escherichia coli, and negative oxygen ions production under UV irradiation. ![]() The results showed that the production of negative oxygen ions was drastically improved by doping with Cu 2O particles under UV irradiation. The effect of Cu 2O particles dopant on the negative oxygen ions production of the TiO 2-treated wood was investigated. Anatase TiO 2 particles with Cu 2O particles were doped on wooden substrates through a two-step method and further modification is employed to create remarkable superamphiphobic surface. In this study, negative oxygen ions production by the TiO 2/Cu 2O-treated wood under UV irradiation was first reported. ![]() Therefore, it is urgent to adopt effective methods to improve the proportion of negative oxygen ions, which are known as “air vitamin”. However, after more than one century, the equilibrium state of the proportion had an obvious change, which the proportion of positive and negative air ions became 1.2 : 1, leading to a surrounding of positive air ions in human living environment. According to statistics, early in the 20th century, the proportion of positive and negative air ions on the earth is 1 : 1.2.
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