Cation-Doped Amino-Functionalized Zirconium MOF Nanocrystals for Enhanced Photocatalytic Degradation of 1-Naphthylamine

The development of efficient and practical photocatalysts is a critical area of research, particularly for environmental applications, such as water purification. Metal-organic frameworks (MOFs) have emerged as promising materials for photocatalytic reactions due to their tunable structures and high surface areas. In this study, eight different MOF samples including UiO-66, UiO-66-NH_2, and their doped versions were synthesized by solvothermal and microwave-assisted methods and fully characterized using XRD, TGA, BET, SEM-EDX, and XPS. These materials were applied as photocatalysts for the degradation of 1-naphthylamine (1-NA) under visible light irradiation. The doped versions, (Ti-Zr)-UiO-66-(NH₂) and Fe-UiO-66-(NH₂), exhibited enhanced visible light absorption and reduced band gaps compared with the pristine UiO-66. Thus, 15%(Ti-Zr)-UiO-66-(NH₂) and Fe-UiO-66-(NH₂) achieved 75% and 65% degradation of 1-NA in 1 h, respectively.. The improved photocatalytic performance was attributed to (i) the functionalization with amino groups, which altered the electronic structure by narrowing the band gap, and (ii) doping with Ti⁴⁺ and Fe³⁺, which improved catalytic activity and reaction efficiency. Titanium doping introduced oxo-bridged hetero-Zr-Ti clusters, while iron doping facilitated a metal-to-cluster charge transfer (MCCT) process, enhancing the optical and catalytic properties of the MOFs. These findings highlight the potential of structural tuning of UiO-66-based MOFs for enhanced photocatalytic degradation of micropollutants in water under visible light, offering a sustainable and energy-efficient solution for water treatment.