Recent advances in titanium metal-organic frameworks and their derived materials: Features, fabrication, and photocatalytic applications

Photocatalysis driven by functionalized metal-organic frameworks (MOFs) is a promising direction for the development of renewable energy conversion and environmental pollution rehabilitation by direct utilization of solar energy. Among various MOFs, titanium (Ti)-based MOFs (Ti-MOFs) are an appealing set of MOFs for practical applications due to their relation to the commonly used TiO2, their unique structural features, relatively low toxicity and excellent optical properties. This review summarizes recent research progress on Ti-MOFs and their composites as well as the porous materials derived from them in photocatalytic applications. The selection of appropriate central metal ions and organic ligands has significant influence on the fabrication of Ti-MOFs with good photocatalytic properties. To regulate the photoresponse and photocatalytic activity, controllable integration of a Ti-MOF system with photo-sensitive materials, resulting in the formation of new multifunctional hybrids, is required. In addition, the calcination of Ti-MOF precursors provides a useful method for preparing promising photocatalysts with novel structures, close contact interfaces, and easy regulation. Finally, the opportunities and challenges for future exploration of Ti-MOFs are discussed from a critical perspective along with those of their composites and derived porous materials.