Visible-Light-Driven Degradation of Organic Dyes Using Novel β- Amino-Modified Cu-BTC MOFs: Toward Clean Water Solutions

Abstract In this study, the synthesis and characterization of novel β-amino-functionalized Cu-BTC-MOFs and their photocatalytic performance for dye degradation were carried out. The modified MOFs, denoted as MOF@3A3NP, MOF@3A4HP, and MOF@3A4H3MP, correspond to Cu-BTC functionalized with 3-amino-3-(3-nitrophenyl)propanoic acid, 3-amino-3-(4-hydroxyphenyl)propanoic acid, and 3-amino-3-(4-hydroxy-3-methoxyphenyl)propanoic acid, respectively. PXRD analysis confirmed the synthesis of MOFs having a crystalline structure and FTIR spectroscopy revealed the successful grafting of β-amino functional groups onto the Cu-BTC surface, evidenced by additional peaks at 2130–2233 cm⁻¹ and 3350 cm⁻¹. The modified Cu-BTC-MOF exhibited a reduced band-gap energy compared to the unmodified Cu-BTC (2.9 eV) which indicated improved light absorption and charge separation. The β-amino-functionalized Cu-BTC-MOFs demonstrated excellent photocatalytic performance, degrading 95%, 98%, and 99% of methyl green, and 85%, 98%, and 99% of methyl orange in 70 minutes upon exposure to visible light using MOF@3A4HP, MOF@3A4H3MP, and MOF@3A3NP, respectively. This improved photocatalytic activity can be ascribed to the morphological modifications, and reduced optical band gap due to amino-functionalized MOFs. These factors highlight the potential of β-amino-functionalized Cu-BTC-MOFs as promising photocatalysts for the efficient degradation of both cationic and anionic dyes.