Rational design of BODIPY-functionalized MOF photocatalysts for highly efficient hydrogen production

Abstract

Photocatalytic hydrogen production through water reduction, driven by hydrogen's high energy density and environmental sustainability, represents a significant pathway for meeting future energy needs and is considered one of the most promising strategies. A major challenge is developing a photocatalyst that is sustainable, stable, and environmentally friendly and has a large surface area. Although various MOF-based photocatalysts incorporating porphyrins, phthalocyanines, or other organic dyes have been extensively explored, studies utilizing BODIPY as a functional chromophore remain scarce. The combination of MOFs with BODIPY units offers a unique platform that couples the structural tunability and stability of MOFs with the excellent light-harvesting and electron-accepting properties of the BODIPY dyes. However, strategies for the systematic design and synthesis of BODIPY–MOF hybrid photocatalysts for hydrogen evolution are still very limited. In this study, the UiO-66-NH₂ structure was modified with BODIPY compounds containing thiophene (BD2) and phenyl (BD4) units, resulting in the synthesis of BD2/UiO-66-NH₂ and BD4/UiO-66-NH₂, respectively. As a result of the 6-hour photocatalytic water splitting experiments, the reaction kinetics of UiO-66-NH₂, BD2/UiO-66-NH₂, and BD4/UiO-66-NH₂ were calculated to be 3013 μmol g⁻¹ h⁻¹, 14 237 μmol g⁻¹ h⁻¹ (4.7-fold increase compared to UiO-66-NH₂), and 21 179 μmol g⁻¹ h⁻¹ (7-fold increase compared to UiO-66-NH₂), respectively. Based on the band structure and photoelectrochemical results, the observed behavior is consistent with the S-scheme charge-transfer pathway for the photocatalytic process. This study provides new insights into integrating BODIPY chromophores into MOF frameworks, establishing a promising design concept for the development of efficient dye–MOF hybrid photocatalysts for solar-to-hydrogen conversion.