Abstract
Titanium-substituted cerium-oxo-based UiO MOFs with terephthalate linkers modified by various groups (-Br, -NH2, -NO2) or their derivatives (N-heterocyclic or biphenyl groups) were combined with titanium dioxide in a multistep route to obtain a core-shell-like architecture. DFT simulations showed that Ce- and bimetallic Ti/Ce-MOFs exhibited different charge compensation. Extended characterization revealed the formation of hetero-junctions between the (Ti/Ce)UiO-X MOFs and TiO2 nanoflowers, suitable band edge positions, and high specific surface area and porosity, which resulted in effective electron transfer and excellent photocatalytic activity. The photoactivity of the (Ti/Ce)UiO-X@TiO2 composites for hydrogen production or phenol degradation varied according to the order -NH2 > biphenyl > -N- > -H > -Br > -NO2 > pristine TiO2 or -Br > -NH2 > -NO2 > -N-> -H > biphenyl > pristine TiO2. The photocatalytic hydrogen production rate of (Ti/Ce)UiO-66-NH2@TiO2 was 4724 and 19.3 μmol·g_(cat)~(-1) after 4 h of UV-Vis and visible light irradiation, which were 79 and 19 times higher than that of pristine rutile, respectively.
NSTL