Extending the visible light absorption of NH2-UiO-66 through diazotization reaction for photocatalytic chromium (VI) reduction

Abstract

The optical properties of NH 2 -UiO-66 as a visible light-active metal organic framework was further enhanced through the diazotization reaction with π-conjugated 1-naphthol reagent. Diffuse re ectance UV-Vis spectrum of diazotized MOF, named as Azo-UiO-66, exhibited a signi cant red shift compared to unfunctionalized NH 2 -UiO-66 due to the formation of diazo compound. Also, Tauc calculations indicated considerable decrease in band gap energy from 2.68 to 1.7 eV, resulted in improvement of visible light harvesting. Furthermore, other physicochemical techniques e.g. X-ray diffraction (XRD), N 2 adsorption-desorption analysis, thermogravimetric analysis (TGA), energy dispersive X-ray (EDX), and CHN elemental analyses demonstrated the successful MOF diazotization with 1-naphthol and preservation of NH 2 -UiO-66 framework upon post modi cation process. The reduction of hexavalent chromium, Cr(VI), as a serious contaminant in wastewater to less toxic Cr(III) was performed over prepared photocatalyst, which demonstrated the positive role of ligand functionalization and enhancement of visible light absorption on overall photocatalytic performance of Azo-UiO-66.

Zirconium‐based metal–organic framework and functionalized carbon black composite for simultaneous electrochemical detection of tert‐butylhydroquinone and butylhydroxyanisole

“…Furthermore, the peaks observed at 1496 and 1433 cm −1 originate from the vibrations of the aromatic ring skeleton and C–C bond, respectively 45 . Additionally, the peak at 1380 cm −1 corresponds to the tensile vibration of C–O, whereas that at 1256 cm −1 corresponds to the tensile vibration of C–N in NH 2 –UiO‐66@FCB 52 . Moreover, peaks corresponding to the Zr–O bond appear between 650 and 800 cm −1 53 .…”

“…45 Additionally, the peak at 1380 cm À1 corresponds to the tensile vibration of C-O, whereas that at 1256 cm À1 corresponds to the tensile vibration of C-N in NH 2 -UiO-66@FCB. 52 Moreover, peaks corresponding to the Zr-O bond appear between 650 and 800 cm À1 . 53 Overall, the characteristic peaks of NH 2 -UiO-66 and NH 2 -UiO-F I G U R E 3 (a) XPS survey spectrum of the NH 2 -UiO-66@FCB and NH 2 -UiO-66; XPS spectrum of C1s (b), N1s (c), O1s (d), and Zr3d (e) for the NH 2 -UiO-66@FCB and NH 2 -UiO-66; (f) the XRD diagram of the NH 2 -UiO-66 (blue), FCB (green), and NH 2 -UiO-66@FCB composite (red).…”