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

Abstract

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.