Metal-organic frameworks (MOFs) have received significant interest as a promising photocatalyst for environmental remediation due to its high surface area and porous nature. The small pores (<2 nm) in microporous MOFs help the adsorption of small molecules but limits diffusion and accessing of bigger molecules from MOF cavities, thus preventing their applications in some situation. The aim of this work is to fabricate mesoporous MOF composite with larger pore sizes (>2 nm) and open pore cavities that can provide right pathways for ingoing and outgoing of molecules during catalysis. Herein, we successfully report stable mesoporous MIL-100(Fe) loaded with ZnO NS by an in situ self-assembly method. The prepared samples were characterized by Brunauer–Emmett–Teller (BET) and N 2 adsorption-desorption isotherm to study their surface area and porosity. The catalytic performance of mesoporous MIL-100(Fe) was approximately 2–3 order of magnitude more than that of microporous MIL-100(Fe). Such higher catalytic activity in mesoporous MIL-100(Fe) can be ascribed to its mesocellular structure which can improve the molecular diffusion and accessibility inside MOF channels. The charge separation efficiency and photo-Fenton activity of mesoporous MIL-100(Fe) can further be increased by introduction of certain amount of ZnO NS and H 2 O 2 . Moreover, the as synthesized sample shows higher photo-Fenton degradation efficiency at lower pH value with certain amount of H 2 O 2 . Lastly, the possible catalytic mechanism has been tentatively proposed. This study not only used for the pollutants degradation but also provide useful platform for the application of mesoporous MOFs as an efficient photo-Fenton activity to various other fields.
Iron-based single-atom catalysts (Fe-SACs) containing Fe–N 4 active sites have shown immense potential in the oxygen reduction reaction (ORR). However, the limited ability to adsorb O 2 and catalyze subsequent O–O bond breaking on Fe–N 4 sites has hindered their full potential, especially in acidic electrolytes. Here, we present an approach by utilizing a tunable curved surface to enhance the activity of Fe–N 4 active sites, with theoretical calculations, demonstrating that Fe–N 4 sites anchored on low–curvature surfaces (lc-Fe-N 4 ) is favirable for ORR. Experimental results show that the catalyst exhibits excellent catalytic activity and stability for ORR in acidic electrolytes, with a half-wave potential of 0.82 V vs. RHE, approaching that of commercial Pt/C. This work develops an approach for promoting the catalytic activity by anchoring atomically dispersed Fe–N 4 sites, unlocking their potential for extended use in electrocatalytic and energy storage applications.
Guihua Xu,Qiaoning He,Kexin Huang,Ying Wang,Chun Pu,Ganggang Chang,Xiaoyu Yang
Benefiting from their unique properties including faster mass transfer, more exposed active sites and large molecule recognition, hierarchically porous metal–organic frameworks (HP-MOFs), in the form of ultrasmall nanoparticles (NPs) and having self-assembled interparticle mesopores, have garnered greater attention in recent years that given to typical MOFs. However, controllable synthesis of HP-MOFs on the nanoscale remains a significant challenge. Herein, for the first time, a facile top-down acid etching strategy was developed to fabricate a series of nanosized (∼15 nm) mesoporous MOF, HP-UiO-66-NH 2 (Hf). The sizes of mesopores in this material can be effectively tuned by simply controlling the concentration of propionic acid (PA) utilized in the preparation solution. Interestingly, the generated mesoporous HP-UiO-66-NH 2 (Hf) has excellent stability and can be readily constructed by using PA etching solution that has been recycled at least four times. Remarkably, HP-UiO-66-NH 2 (Hf) displays a high size-selectivity for adsorption of enzymes. Associated with its highly matched mesopore size, the nanocomposite generated by complexation with glucose oxidase (GOD), [email protected] 2 (Hf) has a higher catalytic activity and a significantly enhanced stability (recycled at least 7 times) in promoting oxidation of glucose compared to its MOF counterpart, [email protected] 2 (Hf) and native GOD .
危险品化学品经营许可证（带存储）