Functionalization of a Metal-Organic Framework Semiconductor for Tuned Band Structure and Catalytic Activity

This study presents two strategies to modify the thermally stable crystalline UiO-66(Zr) metal-organic framework (MOF) structure, in which the organic struts have been functionalized to modulate the electronic band structure and the catalytic activity toward selective oxidation of benzyl alcohol to benzaldehyde. The two strategies include the functionalization of the organic struts with branched ligands and manually creating structural defects with unsaturated organic linkers. The computational and experimental results show that functional groups such as -NH2 and -NO2 attached to the main organic strut modify the electronic environment of the photoactive aromatic carbon and thereby reduce the optical bandgap by 1 eV, improving the photocatalytic activity. Whereas the introduction of structural defects by the organic linker desaturation provides a shift in the highest occupied molecular orbital (HOMO), resulting from a decrease in the strut coordination with the inorganic knots, modulating the catalytic activity without light illumination.