Hydrogen bond-assisted construction of MOF/semiconductor heterojunction photocatalysts for highly efficient electron transfer

It remains challenging for the fabrication of metal-organic framework (MOF)/semiconductor heterojunction photocatalysts with close contact interfaces. In this work, a novel MOF/semiconductor heterojunction photocatalyst consisting of H2O2-modified TiO2 nanotubes (H2O2-TNTs) and MIL-88B(Fe)-NH2 (labeled as H-T/M) was firstly constructed based on the hydrogen-bonded combination between the O atoms from -OOH groups resulting from H2O2 absorbed on the surface of TiO2 nanotubes and the H atoms of the -NH2 group in MOF. The significantly enhanced photocatalytic property of the H-T/M heterojunction for reducing Cr(VI) could be ascribed to the accelerated interfacial electron transfer dynamics by a channel of hydrogen bonds (N center dot center dot center dot H-O-O-Ti), which could be extracted from the femtosecond transient absorption spectroscopy (fs-TAS). Moreover, the built-in electric field and the differences in charge density based on density functional theory (DFT) calculations could provide the driving force for charge transfer.