2D sodium titanate nanosheet encapsulated Ag2O-TiO2 p-n heterojunction photocatalyst: Improving photocatalytic activity by the enhanced adsorption capacity

Abstract In a photocatalytic reaction, maintaining the high efficiency of photocatalyst under a low concentration of pollutants is a key challenge. In this work, a new 2D sodium titanate nanosheet encapsulated Ag2O-TiO2 (2D NTO/Ag2O-TiO2) p-n heterojunction photocatalyst is proposed to deal with this dilemma. Through a simple plasma electrolytic oxidation (PEO) treatment and ion exchange treatment, a classic Ag2O-TiO2 p-n heterojunction structure is prepared and used as the photoelectric conversion unit in the photocatalyst. Then, through a subsequent hydrothermal treatment, a 2D NTO film that serves as the adsorption unit in the photocatalyst can be produced on the surface of the Ag2O-TiO2 p-n heterojunction layer. Finally, the desired 2D NTO/Ag2O-TiO2 structure is formed. The photocatalyst exhibits superior photocatalytic performance including high degradation rate as well as excellent catalytic stability and durability by combining the high sunlight utilization efficiency and high photoelectric utilization efficiency of the Ag2O-TiO2 p-n heterojunction and the outstanding adsorption performance of the 2D NTO film. Therefore, the problem of photocatalytic slow kinetics under low pollutants concentration is perfectly solved. This work provides a new strategy for the structural design of high-performance photocatalysts.