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Synthesis of core–shell ZIF-67@Co-MOF-74 catalyst with controllable shell thickness and enhanced photocatalytic activity for visible light-driven water oxidation
摘要： In this paper, a core–shell ZIF-67@Co-MOF-74 catalyst was synthesized by coating 2,5-dihydroxyterephthalic acid (DHTP) molecules on the surface of ZIF-67 crystals via the ligand exchange method. Notably, the ZIF-67@Co-MOF-74 catalyst with shell thicknesses of 10 nm, 25 nm and 50 nm can be further obtained by adjusting the mass ratio of ZIF-67 and DHTP. Compared to individual ZIF-67 or Co-MOF-74 catalyst, the as-prepared core–shell MOF catalyst exhibited enhanced photocatalytic activities for light-driven water oxidation reaction. Furthermore, the content of oxygen evolution by water splitting increased gradually with the increase in shell thickness. The formation of crystal defects and the uncoordinated hydroxyl and carboxyl groups on the surface of core–shell MOFs facilitated the exposure of the metal catalytic center and the adsorption of water molecules through hydrogen bonding interactions to react with the catalytic active center effectively. In addition, the photogenerated holes and electrons could be excellently separated and rapidly transferred at the interface of ZIF-67 (core) and Co-MOF-74 (shell), resulting in effective increase in the interfacial charge transfer rate. Furthermore, this simple and novel method is also applicable to three other carboxylic acid ligands, which implies that it may be a general method that can be extended to other ligands for fabricating different core–shell ZIF-67@MOF crystals.
关键词： ZIF-67@Co-MOF-74,ligand exchange method,water oxidation,core–shell,photocatalytic activity
更新于2025-09-04 15:30:14
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Facile fabrication of sandwich-like BiOI/AgI/g-C3N4 composites for efficient photocatalytic degradation of methyl orange and reduction of Cr(VI)
摘要： Construction of heterojunction photocatalyst with excellent charge separation has attracted significant attention for solving the global energy crisis and environmental problems. Herein, a series of sandwich-structured BiOI/AgI/g-C3N4 composites were fabricated by a novel and facile method. The AgI was employed as a charge transmission bridge between BiOI and g-C3N4, which could result in more efficient charge transfer and better separation of charge carriers. The results indicated that the BiOI/AgI/g-C3N4 composites exhibited higher photocatalytic activity for the degradation of methyl orange (MO) and reduction of Cr(VI) than that of pure g-C3N4, BiOI, and BiOI/g-C3N4. The amount of AgI had a remarkable influence on the photocatalytic activity of the BiOI/AgI/g-C3N4 composites. Moreover, the BiOI/AgI/g-C3N4 composites exhibited high stability. Finally, a possible reaction mechanism on degradation of MO and reduction of Cr(VI) solutions over the composites was proposed. This work could facilitate a better understanding on the charge transfer process in the composite systems as well as provide a new approach to the rational design of novel advanced materials for practical photocatalytic application.
关键词： Reaction mechanism,Photocatalytic activity,Nanocomposite,BiOI/AgI/g-C3N4
更新于2025-09-04 15:30:14