Synthesis and Structure of 3D Bis[5‐(2‐pyridyl)tetrazolato]diquacopper(II) Framework: One‐pot Facile Fabrication of a Series of Catalysts Towards Dye Degradation in Sunlight

Abstract

A copper‐based metal‐organic framework (MOF) Bis[5‐(2‐pyridyl)tetrazolato]diaquacopper(II) [{CuP}n], has been designed and structurally characterized by single‐crystal X‐ray crystallography. The three‐dimensional crystal structure belongs to the monoclinic space group P21/c with Z=4. Further a series of isostructural complexes [{Cu1‐xZnxP}n] (x=1, 0.75, 0.5, 0.25, 0), {P=(5‐(2‐pyridyl)tetrazolato)2.2H2O} have been synthesized via a facile one‐pot microwave irradiated solvothermal method. The optical and photocatalytic properties of the synthesized bimetallic complexes were investigated and compared with those of monometallic complexes. The effects of metal substitutions in the ligand backbone were investigated. A striking variation in the bandgap i. e., from 4.1 eV (x=1) to 2.79 eV (x=0) was observed among the catalysts with a minimum value of 1.93 eV (x=0.25). The optimized catalyst Cu0.75Zn0.25P exhibits the highest degradation activity and reached up to 99 % for RhB (rhodamine B) and 96 % for MB (methylene blue) in 120 min of Sunlight, corresponding to the respective photocatalytic degradation rates of 0.0328 min−1 and 0.0301 min−1. The kinetics of the degradation processes were best statistically described by pseudo‐first‐order. The catalyst was also found to have sufficient stability and recyclability with promising applications in removal of organic dye pollutants.

Synthesis and Characterization of a Nano‐Composite CuO@Zn−2‐PTZ {Zn−2‐PTZ=bis[5‐(2‐pyridyltetrazolato)]diaquazinc(II)} for Efficient Photo‐catalytic Degradation of Methylene Blue (MB), Methyl Orange (MO) and mixed(MB‐MO)Dyes in Sunlight

“…Signals at 2961 cm −1 , 1739 cm −1 , 1591 cm −1 and 1375 cm −1 are respectivelyattributed to the stretching of the C−H,C=N and C−N bonds. The Zn−N bond is indicated by the peaks at 756 cm −1 and 666 cm −1 , whereas a new peak in the composite at 557 cm −1 reveals that Cu−N bonds are also generated [39] . Hence the proposed structural composition of CuO@Zn−2‐PTZ has been substantiated by IR spectroscopy.…”

“…Where C 0 is the initial concentration of the dye solution and C being the concentration of the dye solution after time t and k is the photo‐degradation rate constant [39,45] …”

“…The ZnÀ N bond is indicated by the peaks at 756 cm À 1 and 666 cm À 1 , whereas a new peak in the composite at 557 cm À 1 reveals that CuÀ N bonds are also generated. [39] Hence the proposed structural composition of CuO@ZnÀ 2-PTZ has been substantiated by IR spectroscopy.…”

“…Where C 0 is the initial concentration of the dye solution and C being the concentration of the dye solution after time t and k is the photo-degradation rate constant. [39,45] The photocatalytic performances of all the three catalysts are given in Table 1 and their rate constants and correlation coefficients (R 2 ) are given in Table 2. Therefore, the findings indicate that the CuO@ZnÀ 2-PTZ composite has particularly high activity for degradation of methylene blue both singly as well as in the mixed dye (MB-MO) solutions operating under natural sunlight.…”