Facile fabrication of BUC‐21/g‐C₃N₄ composites and their enhanced photocatalytic Cr(VI) reduction performances under simulated sunlight

Abstract

A series of BUC-21/g-C 3 N 4 composites were facilely fabricated from twodimensional metal-organic framework BUC-21 and two-dimensional metal-free polymer semiconductor graphitic carbon nitride (g-C 3 N 4 ) through ball-milling, and characterized via powder X-ray diffraction, Fourier transform infrared spectrometry, thermogravimetric analysis, transmission electron microscopy, and UV-visible diffuse reflectance, X-ray photoelectron and photoluminescence emission spectrometry. The photocatalytic activities of B100G100 (weight ratio of BUC-21 to g-C 3 N 4 being 1:1) towards Cr(VI) reduction were investigated upon the irradiation of simulated sunlight and real sunlight, in which the influences of various organic compounds (tartaric acid, citric acid and oxalic acid) as hole scavengers, pH values (2, 3, 4, 5, 6, 7 and 8) and foreign ions (ions in tap water and real surface water) were also investigated. The results revealed that B100G100 exhibited more outstanding photocatalytic Cr(VI) reduction than individual BUC-21 and g-C 3 N 4 , resulting from enhanced separation of photogenerated electrons and holes, which were confirmed via both photoluminescence emission and electrochemical determination. The B100G100 composite exhibited good reusability and stability after several experimental runs. Also, the corresponding mechanism of photocatalytic reaction was proposed.

Metal–Organic Frameworks in Heterogeneous Catalysis: Recent Progress, New Trends, and Future Perspectives

“…The MIL-53­(Fe)/SnS nanocomposite was prepared by a simple deposition method and was also applied for Cr­(VI) photoreduction, exhibiting a significant reduction rate compared that of its counterparts . A few more examples of merging MOFs with semiconductors have been studied. − …”

Synthesis of Metal Organic Frameworks by Ball-Milling

“…In addition, long-term ball milling may also cause the MOF structure to collapse, lose its periodic structure, and become amorphous [84,85], which is difficult to achieve in a solution phase reaction. The ball milling method can also make it more convenient to combine MOFs and other materials to form binary or even multiple composite materials [18,[86][87][88][89][90][91][92][93], such as GO/MOFs composites [94][95][96][97][98][99] Cu-BTC with truncated octahedral shape, and showed significantly reduction of reaction time and effectively improvement of yield [78].…”

Recent Progress in the Development of MOF-Based Photocatalysts for the Photoreduction of Cr(VI)

“…A zinc-based MOF, BUC-21, was utilized for the preparation of a composite with g-C 3 N 4 via a ball-milling of two as-prepared components in different ratios . BUC-21 was initially prepared using a mix linker of cis -1,3-dibenzyl-2-imidazolidone-4,5-dicarboxylic acid and 4,4′-bipyridine.…”