Rapid synthesis of cerium-UiO-66 MOF nanoparticles for photocatalytic dye degradation

Construction of a series of pH stable Ca-based MOFs, their CO2 adsorption and catalytic activity

In this study, three different solvent systems have been employed to investigate the effect of reaction parameters on the synthesis of four alkaline earth metal-based MOFs namely [Ca(0.5 1,4-phenyl diacetic acid)2(H2O)DMF]∞ (Ca-MOF-1), [Ca(1,4-naphthalene dicarboxylate)DMF]∞ (Ca-MOF-2), [Ca2(0.5 1,2,4,5-benzene tetracarboxylate)2(H2O)3DMF]∞ (Ca-MOF-3) and [Ca2(2,6-naphthalene dicarboxylate)2(H2O)6]∞ (Ca-MOF-4). The crystal structures of these four MOFs have been resolved through single crystal X-ray analysis and the bulk phase purity of these MOFs was assessed using PXRD and FT-IR analysis. To check the stability of these MOFs, thermogravimetric analysis (TGA) was carried out. To analyze the robustness of these MOFs, the PXRD of the samples was also collected at different pH levels. These MOFs were further explored as Lewis acid catalysts for the alcoholysis of epoxides and the activity of these catalysts depend on the open metal sites present in the MOFs. The catalytic activity follows the order: Ca-MOF-2 > Ca-MOF-4 > Ca-MOF-1 > Ca-MOF-3. The activity was also checked with various epoxide substrates using Ca-MOF-2. Density functional theory (DFT) calculations also support this trend with the help of the thermodynamic feasibility of epoxide binding, considering model MOF structures. The weak interaction between the epoxide oxygen and the metal centre of the most stable MOF structure has also been clarified by computational studies.

Amino-Functionalizing Ce-Based MOF UiO-66 for Enhanced CO2 Adsorption and Selectivity

Metal-organic frameworks (MOF) hold great promise for CO2 adsorption due to their high surface areas, tunable pore sizes, and the ability to modify their chemical properties to enhance CO2 affinity. MOFs tagged with functional groups either at linker or metal sites have shown improved CO2 uptake capacity and selectivity. This study focuses on investigating the potential of selective CO2 adsorption using amino functionalization of linker forming Ce-UiO-66. The physicochemical properties and characteristics of MOFs to determine the degree of amino functionalization and structural stability were examined using powder X-ray diffraction (PXRD), Fourier transformer infra-red (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and N2 porosimetry and specific surface area (BET). This work unveils a novel array of results on CO2, N2 and water vapour adsorption on Ce-UiO-66-NH2. The amino-functionalized Ce-UiO-66-NH2 shows 63 % higher CO2 uptake and 84 % higher CO2/N2 selectivity at 273 K and 1 bar over Ce-UiO-66. Ce-UiO-66-NH2 also shows excellent structural stability after gas and vapour sorption making Ce-UiO-66-NH2 potential adsorbent for CO2 capture.

Aminated graphene quantum dots/CdS nanobelts for enhanced photocatalytic degradation of RhB dye under visible light

CdS nanoparticles have wide applications as photocatalysts for degradation of organic pollutants, but due to their limited turnover number and off-pathway charge recombination processes, their degradation efficiency is low. Herein, aminated graphene quantum dots/CdS (GQDs/CdS) nanobelts were successfully fabricated by solvothermal and hydrothermal processes. The prepared GQDs/CdS were characterized by physical methods to investigate their structure, morphology, optical properties, specific surface area, element composition, and chemical state. GQDs/CdS materials promoted efficient charge separation, and showed high efficiency in the photocatalytic degradation of the organic dye Rhodamine B (RhB) under visible light. The degradation efficiency of RhB samples over 0.05 g of catalysts reached 97.40% after 150 min, a much higher efficiency in comparison to pure CdS. Electron paramagnetic resonance (EPR) spectroscopy provided direct evidence for ˙OH and ˙O2- as the reactive oxidative species using DMPO as a spin trap. Consistent with the experimental results, a possible mechanism of RhB photocatalytic degradation by GQDs/CdS under visible light was proposed. This work may provide environmentally friendly photocatalysts for degrading organic dyes and purifying water.

Assembling Ag@CuO/UiO-66-NH2 nanocomposites for efficient photocatalytic degradation of xylene

Achieving efficient and stable photocatalytic degradation of xylene hinges on the advancement of photocatalytic materials with outstanding visible light activity. This low-carbon strategy serves as a promising solution to combat air pollution effectively. In this study, we synthesized a Z-scheme heterojunction Ag@CuO/UiO-66-NH2 nanocomposite by hydrothermal method to investigate its photodegradation properties for xylene gas under visible light conditions. XRD, XPS, SEM, FTIR, and UV-vis analyses were employed to confirm the presence of the Z-scheme heterojunction. The CuO/UiO-66-NH2 (CuU-2) composite has high photocatalytic activity, which is 2.37 times that of the original UiO-66-NH2. The incorporation of Z-scheme heterojunction facilitates efficient charge transfer and separation, leading to a substantial enhancement in photocatalytic activity. The Ag@CuO/UiO-66-NH2 (Ag-1@CuU) composite has the highest photocatalytic activity with a degradation efficiency of 84.12%, which is 3.36 times and 1.41 times that of UiO-66-NH2 and CuO/UiO-66-NH2, respectively. The silver cocatalyst improves the absorption capacity of the composite material to visible light, makes the ultraviolet visible absorption edge redshift, and significantly improves the photocatalytic performance. This study introduces a novel approach for xylene gas degradation and offers a versatile strategy for designing and synthesizing metal-organic framework (MOF)-based photocatalysts with exceptional performance.