Tuning the Photocatalytic Activity of Ti-Based Metal-Organic Frameworks through Modulator Defect-Engineered Functionalization

[EN] Defect engineering is a valuable tool to tune the photocatalytic activity of metal-organic frameworks (MOFs). Inducing defects through the attachment of functionalized modulators can introduce cooperative units that can tune the bandgap of the material and enhance their chemical, thermal, and photostabilities among other properties. However, the majority of defect engineering studies for photocatalytic applications are limited to Zr-based MOFs, and there is still a lack of interrelation between synthetic variables, the resultant MOF properties, and their effect on their photocatalytic performance. We report a comprehensive study on the defect engineering of the titanium heterometallic MOF MW-10 by fluoro- and hydroxy-isophthalic acid (Iso) modulators, rationalizing the effect of the materials' properties on their photocatalytic activity for hydrogen production. The Iso-OH modified MOFs present a volcano-type profile with a 2.3-fold increase in comparison to the pristine materials, whereas the Iso-F modified samples have a gradual increase with up to a 4.2-fold enhancement. It has been demonstrated that similar to 9% of Iso-OH modulator incorporation produces similar to 40% defects, inducing band gap reduction and longer excited states lifetime. Similar defect percentages have been generated upon near 40% Iso-F modulator incorporation; however, negligible band gap changes and shorter excited states lifetimes were determined. The higher photocatalytic activity in Iso-F modulator derived MOF has been attributed to the effect of the divergent defect-compensation modes on the materials' photostability and to the increase in the external surface area upon introduction of Iso-F modulator.This publication is part of a project that has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska (Grant Agreement No. 837804, DefTiMOFs, MSCA-IF-2018). I.A.L. thanks the European Union's Horizon 2020 research and innovation programme for the receipt of Marie Sklodowska-Curie Actions Individual Fellowship and thanks The University of Valencia and Functional Materials Research Group for research facilities and the Maria de Maeztu Units of Excellence Programme (CEX-2019-000919-M). H.S. also thanks the European Union's Horizon 2020 research and innovation programme Solar2Chem, under the Marie Sklodowska-Curie Grant Agreement No. 861151. H.G. and J.A. acknowledge financial support by the Spanish Ministry of Science and Innovation (RTI2018-98237-CO2-1) and Generalitat Valenciana (Prometeo 2017-083).Abánades Lázaro, I.; Szalad, H.; Valiente, P.; Albero-Sancho, J.; García Gómez, H.; Martí-Gastaldo, C. (2022). Tuning the Photocatalytic Activity of Ti-Based Metal-Organic Frameworks through Modulator Defect-Engineered Functionalization. ACS Applied Materials & Interfaces. 14(18):21007-21017. https://doi.org/10.1021/acsami.2c026682100721017141