Role of Oxygen Vacancies in Plant Molecule Assistant Prepared Au/TiO2 Nanotube Array Catalyst for the Photoelectrocatalytic Degradation of Methyl Orange

The construction of TiO2 nanotube arrays with oxygen vacancies is widely used for the photoelectrocatalytic degradation of organic pollutants, but crystal defects often reduce the stability of the catalyst. This article is mainly in the preparation of a supported porous catalyst by anodic oxidation of Ti foil and loading of Au nanoparticles with the assistance of Cinnamomum camphora leaf extract. The obtained Au/TiO2 nanotube array catalyst was applied to the photoelectrocatalytic degradation of methyl orange. The photoelectrocatalytic degradation efficiency was enhanced with the removal of plant molecules and the construction of oxygen vacancies by calcination in anaerobic conditions, and the reaction rate constant increased by 66% when the catalyst was heat pretreated at 673 K. In addition, the catalytic activity of Au/TiO2 nanotube array catalyst was maintained at a high level after 5 cycles of application. After characterization by X-ray photoelectron spectroscopy, thermogravimetric analyses, Fourier transform infrared, electrochemical impedance spectroscopy, and photoluminescence, the plant molecules played important roles in the reduction of gold ions, nucleation of gold atoms, and stabilization of oxygen vacancies to prevent collapse. This method for the preparation of photoelectrocatalysts with the assistance of plant molecules and the construction of oxygen vacancies would be expected to apply in the development of high stability supported catalysts toward degradation of organic pollutants.