Metal Exchange of ZIF-8 and ZIF-67 Nanoparticles with Fe(II) for Enhanced Photocatalytic Performance

Abstract

Zeolitic imidazolate frameworks (ZIFs), such as ZIF-8 and ZIF-67, were found to be efficient catalysts. However, ZIFs are not used much in photocatalysis due to their low photocatalytic activity for most reactions. The photocatalytic activity can be improved by modifying the framework by exchanging the Zn­(II) ions (ZIF-8) and Co­(II) ions (ZIF-67) with a more photocatalytically active metal­(II) ion to form an efficient bimetallic ZIF photocatalyst. Redox-active iron (Fe)-based materials are known to be highly potent photocatalysts. Thus, incorporating iron into ZIFs could significantly enhance their photocatalytic performance. In this study, we modified nanosized ZIF-8­(Zn) and ZIF-67­(Co) via metal (Fe2+) exchange to produce bimetallic frameworks that are photocatalytically more active than their parent ZIFs. Nanosized ZIF-8 and ZIF-67 were synthesized isothermally in either water or methanol under ambient conditions. From these, Fe-containing bimetallic ZIF-8 and ZIF-67 nanoparticles were synthesized via the metal exchange, and their performance on the photocatalytic degradation of dye was evaluated. The morphology and crystal structures of the pristine ZIF-8 and ZIF-67 nanoparticles were retained to a large extent during the iron exchange. Their Brunauer–Emmett–Teller (BET) surface areas decreased by less than 15% for nZIF-8 and less than 12% for nZIF-67. The binding energy values on X-ray photoelectron spectroscopy (XPS) confirmed the preservation of the oxidation state of Fe­(II) during the exchange process. A remarkably higher catalytic activity was observed for the photocatalytic degradation of dye by the Fe-exchanged nZIF-8 and nZIF-67 compared to their parent ZIFs. This proved that the incorporation of Fe­(II) centers into the ZIF framework enhanced the photocatalytic activity of the framework dramatically. In addition, these catalysts can be regenerated and reused without an appreciable loss in activity.

Synergistic Effect of Bimetallic MOF Modified Separator for Long Cycle Life Lithium‐Sulfur Batteries

“…The PXRD clearly shows that the peak intensity of the Fe‐ZIFs decreased slightly as compared to those of the parent ZIF‐8, suggesting the loss of crystallinity during the metal exchange from Zn 2+ to Fe 2+ , which might be due to the octahedral coordination of Fe (II) into tetrahedral coordination. [ 19 ] Furthermore, a noticeable transformation in color from white (ZIF‐8) to light brown (Fe‐ZIF‐8) was observed (insets of Figure 1b).…”

Enhancing the Catalytic Activity of Zeolitic Imidazolate Frameworks (ZIFs) via an Etching and Regrowth Method for CO2 Cycloaddition Reaction

“…Zeolitic imidazolate frameworks (ZIFs) are one representative subclass of metal organic frameworks (MOFs) and have been employed as catalysts for thermally driven CO 2 cycloaddition reaction. − For instance, Park et al explored the catalytic potential of ZIF-90 for CO 2 cycloaddition with propylene oxide and found that a high yield (ca. 81%) of propylene carbonate was achievable at 8 h by ZIF-90 under 1.2 MPa CO 2 and 120 °C .…”

Enhanced Luminescence of Dye-Decorated ZIF-8 Composite Films via Controllable D–A Interactions for White Light Emission

“…The peaks at ∼995 and ∼1175 cm –1 were corresponding to CC–N twisting and C–N bending vibration, respectively. The peak at ∼1015 cm –1 belonged to C–H out-of-plane bending vibration of CH 3 . , Moreover, a broad absorption band at the range of 3200–2200 cm –1 indicated the existence of N–H stretching vibration due to protonated imidazole and the peak at ∼3400 cm –1 was associated with O–H stretching vibration. − Additionally, the peak (1591 cm –1 ) with the highest relative intensity was attributed to CC/CN or CO stretching vibration due to the presence of conjugated structures in Hmim or H 3 BTC ligands . These results indicated that ZIF-8 frameworks with protonated imidazole structures have been formed (Figure ).…”