Construction of atomic-level charge transfer channel in Bi12O17Cl2/MXene heterojunctions for improved visible-light photocatalytic performance

Exploring efficient co-catalysts to accurately steer the charge separation of semiconductor photocatalysts is highly desired yet remains challenging. Here, we tackle the significant challenge by in situ growing the Bi12O17Cl2 photocatalyst onto two-dimensional (2D) Cl-terminated Ti3C2 MXene to construct 2D/2D heterojunction of Bi12O17Cl2 and Ti3C2. Firstly, 2D few-layered Ti3C2 MXene with chlorine groups has been successfully synthesized by Lewis acidic etching strategy with subsequent ultrasonic exfoliation. The grafting of chlorine terminations on the surface of MXene serves as nucleating centers and growth platform, resulting in the formation of strong interfacial bonds (Bi–Cl–Ti) between Bi12O17Cl2 and Ti3C2. These strong bonds can facilitate the separation and transfer of photo-generated charge carriers between Bi12O17Cl2 photocatalyst and Ti3C2 cocatalyst. As expected, the photocatalytic degradation rate of Bi12O17Cl2/Ti3C2 hybrids is 9.7 times higher than that of bare Bi12O17Cl2 nanosheets. This work not only exhibits a new design concept to effectively steer the charge separation for photocatalysis, but also gives a reference for constructing efficient MXene-based photocatalytic systems.Graphical abstract