In or on, a study of the influence of the binding site for TiO 2 and MIL-101(Cr).

In this work, TiO 2 was formed in situ in the internal pores and on the surface of MIL-101(Cr). Density functional theory (DFT) calculations demonstrate that the difference in the binding sites of TiO 2 can be attributed to the different solvents used. The two composites were used to photodegrade methyl orange (MO), and the photocatalytic efficiency of TiO 2 -in-MIL-101(Cr) (90.1% in 120 min) was much stronger than that of TiO 2 -on-MIL-101(Cr) (14% in 120 min). This is the first work to study the influence of the binding site of TiO 2 and MIL-101(Cr). The results show that MIL-101(Cr) modification with TiO 2 can promote electron-hole separation, and TiO 2 -in-MIL-101(Cr) has better performance. Interestingly, the two prepared composites have distinct electron transfer processes. For TiO 2 -on-MIL-101(Cr), radical trapping and electron paramagnetic resonance (EPR) studies show that O 2 ˙ - is the main reactive oxygen species. Based on its band structure, it can be concluded that the electron transfer process of TiO 2 -on-MIL-101(Cr) conforms to that of a type II heterojunction. However, for TiO 2 -in-MIL-101(Cr), the EPR and DFT results show that 1 O 2 is the active substance that is formed from O 2 through energy transfer. Therefore, the influence of binding sites should be considered for the improvement of MOF materials.