Effect of organic compounds and rough inorganic layer formed by plasma electrolytic oxidation on photocatalytic performance

Abstract

Plasma electrolytic oxidation and dip chemical coating as fabrication techniques are performed in ambient temperature and pressure, giving a competitive-edge in the commercial applicability. Thus, we proposed new compositions of flower-like hybrid materials, MgO-TiO2-HQ(8-hydroxyquinoline), MgO-TiO2-HQ-APY(2-aminopyridine) and MgO-TiO2-HQ-APH(2-aminophenol), as photocatalysis with high corrosion resistance via a combination of plasma electrolytic oxidation and dip chemical coating in which 8-HQ, 2-APY, and 2-APH were used as the organic components. TiO2-HQ-APY and MgO-TiO2-HQ-APH exhibited improved simultaneous electrochemical and photocatalytic performance on photodecomposition of methylene blue (MB) in an aqueous solution in the presence of ultraviolet-visible irradiation comparing to that of MgO-TiO2-HQ. The synergistic effects of organic components anchored on TiO2 and MgO containing inorganic layer were the main source for enhanced anticorrosion resistance. The MgO-TiO2-HQ and MgO-TiO2-HQ-APH could be recovered simply by a magnet and reused several times with no significant diminution in high stability photocatalytic performance during catalytic oxidation. The work indicated that synergistic effects of aromatic heterocycles on TiO2 and MgO containing inorganic layer played key role in enhancing photocatalytic activity and electrochemical behavior. To support the experimental section, quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELOMO), and gap energy (ΔE) were calculated using density functional theory.