Understanding Photocatalytic Activity Dependence on Node Topology in Ti-Based Metal–Organic Frameworks

Despite the drive to develop more efficient Ti-based
metal–organic
framework (MOF) photocatalysts, MIL-125-NH2 is still the
benchmark, and only a few design principles have been offered to improve
photocatalytic performance. Linker functionalization in Ti MOFs has
been shown to enable photocatalysis under visible light by closing
the electronic band gap, significantly improving charge carrier lifetimes.
Limited by known Ti-based MOFs, the role of node nuclearity and topology
on photocatalytic activity remains unclear. Here, we report a new
MOF, ICGM-1, a 3D-connected framework featuring 1D Ti–O rods.
Photocatalytic hydrogen evolution reveals a significant difference
in activity, which we attribute solely to node geometry. Using time-resolved
spectroscopy and DFT calculations, we ascribe these differences to
subtle electronic and geometric properties, paving the way for the
development of Ti-MOF photocatalysts.