Construction of Ti3C2Tx templated MIL-88b(Fe) based heterojunction for enhanced photocatalytic degradation of organic pollutant: The influence of surface chemical states

Heterojunction construction is extensively adopted to improve the poor photocatalytic ability caused by insufficient photo-generated charge carrier separation. However, the influence mechanism of the surface chemical states of heterojunction materials on the migration and separation of photo-generated charges remains unclear. In this work, surface -OH termination controlled Ti3C2Tx templating heterojunction, Ti3C2Tx/MIL-88b(Fe) (HAMM) was designed and successfully prepared. The physicochemical properties of prepared samples were characterized by XRD, TEM, XPS and FT-IR, etc. The results showed that after a 3 h alkalization, the maximum number of -OH groups on the surface of Ti3C2Tx can be obtained. The quantity of surface -OH terminations of Ti3C2Tx affected the photocatalytic ability of heterojunction. Compared with that of MIL-88b(Fe), the photocatalytic ability of HAMM was largely enhanced. The degradation kinetic constant of 3HAMM is 198.2 times higher than that of MIL-88b(Fe). The improvement of the photocatalytic ability can be attributed the following two aspects. The formation of Fe-O between Ti3C2Tx and MIL-88b(Fe) acted as an efficient charge transfer channel and reduced charge transfer resistance. The decreased Fermi level(EF) of Ti3C2Tx caused by enhancement of -OH termination quantity widened the EF difference between the two materials, efficiently driving the charge transfer and further facilitating the separation of photo-generated electron-hole pairs. This research offers a novel concept for creating highly effective photocatalysts through atomic-level engineering of heterojunctions.