The PDINH decorated NH2-UiO-67 MOF for promoted photocatalytic Cr(VI) reduction: Performance, and mechanism

Abstract

A series of composite materials comprising NH₂-UiO-67 metal-organic framework (MOF) and highly π-conjugated 3,4,9,10-perylenetetracarboxylic diimide (PDINH) was synthesized via a facile ball-milling process. These hetero-conjugated MOFs, denoted as PNU-67(X) with varying amounts of PDINH (X = 0.5 %, 1 %, 2 %, and 3 % wt), were evaluated for their photoreduction of Cr(VI) to Cr(III) under visible light irradiation. Systematic investigations revealed a direct correlation between increasing PDINH content and enhancing the conductivity of the MOFs. Additionally, the incorporation of PDINH motifs significantly improved CO₂ capture capability by increasing charge transfer, charge separation, and light absorption. To elucidate the impact of various factors on the photocatalytic performance of PNU-67(3) in Cr(VI) remediation, a comprehensive study was conducted. These factors included pH, initial Cr(VI) concentration, catalyst dosage, scavengers, and scavenger concentration. Notably, PNU-67(3) (5 mg/L) demonstrated 100 % photoreduction efficiency within 35 min, highlighting its potential application in catalyst loading and efficiency compared to other reported UiO-type MOFs. Furthermore, the composites exhibited exceptional stability and reproducibility throughout multiple experimental cycles. Overall, this research presents a promising avenue for constructing heterojunction photocatalysts by integrating MOFs and organic PDINH molecules, offering a viable solution for wastewater remediation.