Mechanical Alloying in Zeolitic Imidazolate Framework for Enhanced Photocatalytic Dye Degradation

Abstract

A ball milling approach has been performed for isostructural ZnZIF-8 and CoZIF-8 in a 1:1 molar ratio to produce the amorphous (a) solid solution state (aZn 0.5 Co 0.5 ZIF-8). It further transformed to a crystalline (c) solid solution state (cZn 0.5 Co 0.5 ZIF-8) by exposing 95% relative humidity (RH) at 25 °C for 72 h. Unique heterometal solid solution structure and high catalytic active sites of aZn 0.5 Co 0.5 ZIF-8 showed excellent photocatalytic performance for the degradation of methylene blue dye under visible light source. The catalytic efficiency of aZn 0.5 Co 0.5 ZIF-8 (97.9%) is much higher than the pristine (p) as well as the amorphous state (a) of ZnZIF-8/CoZIF-8 and cZn 0.5 Co 0.5 ZIF-8.

A series of isostructural metal–organic frameworks for an enhanced electro-catalytic oxygen evolution reaction

“…24 Thus, it is clear that crystallization by vapor exposure of the amorphous state depends on the preservation of the coordination environment in amorphous states. 25 In order to check the effect of ball milling, our three synthesized isostructural MOF crystals were degassed thoroughly to make them guest free and named p CoTIA, p CdTIA, and p ZnTIA ( p stands for the pristine state). Ball milling treatment of these guest-free MOFs was individually performed at 400 rpm for two hours under an Ar atmosphere (Experimental procedure, section S2, ESI†).…”

Role of N-Rich Coordination Environment in Metal–Organic Frameworks for Enhanced Photocatalytic Dye Degradation

“…It is clear from the results that the reaction rate best fits the pseudo-first-order kinetics with a R 2 (linear regression coefficient) value close to 1. Table S1 shows the rate constant ( k ) value obtained from the straight line plot of ln C / C 0 vs time. , …”

“…The efficiency of degradation was found to be 25.4, 28.8, 97.9, and 98.9% at pH 3, 5, 7, and 9, respectively (Figure b). This result indicates that the degradation efficiency was optimum in the pH range between 7 and 9. , It should be noted that among all catalysts, ZnPHTIA displays enhanced photocatalytic efficiency of degradation. Therefore, detailed characterization was performed on the ZnPHTIA catalyst.…”

“…It is clear from the plot (Figure S13) that fluorescent active 2-hydroxyterephthalic acid (TA · OH) is generated, and its intensity increased from 0 to 120 min (detailed synthesis, Section S3.4). This indicates that a large amount of OH · radicals were produced which exhibit characteristic fluorescence emission around 430 nm …”

Designed Synthesis of Fe/Zr Bimetallic Organic Framework to Enhance the Selective Conversion of H2S to Sulfur

“…Among the myriad family of MOFs, UIO-66­(Zr), which is constructed by Zr­(IV)-carboxylate clusters (Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 (C 8 H 4 O 4 ) 6 ) and 12 bidentate terephthalic acid (H 2 BDC) to form regular dodecahedral secondary structural units, has unique advantages in the field of catalysis because of its excellent thermal and chemical stability. − Nevertheless, the problem of limited catalytic activity restricts its further development. In order to boost the activity of catalysts, the common strategies are mainly to control the composition, structure, morphology, and particle size of catalysts because these factors have a significant impact on their catalytic properties. − Selective oxidation of H 2 S, as a gas–solid heterogeneous oxidation reaction, mainly occurs in the active center of the catalysts. Therefore, it is highly feasible to enhance the catalytic properties by doping heterometal atoms, which will provide more catalytic active sites and create synergistic effects between different metals. − On this basis, the smaller nanoparticles and larger surface areas not only improve the accessibility of the active sites but also enhance their atomic utilization efficiency. − Based on the above discussion, the incorporation of Fe atoms into the framework of UIO-66­(Zr) is highly attractive for the fabrication of bimetallic MOF catalysts with more accessible and reactive active sites for selective conversion of H 2 S to S.…”