Composite nanoarchitectonics with TiO₂ nanocrystals and superior thin Ti₃C₂T_x nanosheets towards efficient NO removal

Accordion-like Ti₃C₂T_x MXene supplied a possibility to construct two-dimensional composites with novel performance. In this paper, few-layered Ti₃C₂T_x MXene was created via a chemical etching strategy. The oxidation in-situ using a powerful alkaline solution resulted successfully in TiO₂ nanocrystals grown on Ti₃C₂T_x nanosheets. The alkaline treatment adjusted terminations of the Ti₃C₂T_x MXene and controlled the oxidation degree by changing temperature. The ratio of Ti₃C₂T_x and TiO₂ was finally optimized. Because of Ti₃C₂T_x nanosheets with well conductivity and excellent light absorption as well as TiO₂ nanocrystal arrays on Ti₃C₂T_x nanosheets with a high specific surface area and more active sites, TiO₂/Ti₃C₂T_x composites revealed excellent photocatalystic activity, especially for NO removal. The improvement of separation and transfer efficiency of phootogenerated carriers is ascribed to the microstructure of TiO₂/Ti₃C₂T_x composites. The composite sample synthesized at 75 °C revealed the best NO removal efficiency, in which 70% of NO was removed at a concentration of 600 ppb. This study offers a new thought for preparing high performance MXene-based photocatalysts.