Co Nanoparticles Embedded in 2D N‑Doped Porous Carbon Nanosheets for Evaluating Acetylcholinesterase Activity

Here, we reported a facile strategy to prepare Co nanoparticles (NPs) encapsulated in two-dimensional (2D) N-doped porous carbon nanosheets (2D Co/NC) via pyrolyzing Zn/Co bimetallic metal–organic framework (MOF) nanosheets, which were prepared in aqueous solution. The successful synthesis of Zn/Co bimetallic MOF nanosheets and 2D Co/NC was demonstrated by various characterization techniques. The optimized 2D Co0.6/NC-700 and three-dimensional (3D) Co0.6/NC-700 show catalase- and oxidase-like activities. They can break down H2O2 into O2 and oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue product, while the former displays superior performance to its 3D Co0.6/NC-700 aggregated nanoparticles. Specifically, the oxidase-mimicking activity and catalase-like activity of 2D Co0.6/NC-700 are 1.64-fold and 6.9-fold those of 3D Co0.6/NC-700, respectively. Relative to 3D Co0.6/NC-700 aggregates, the improvement of the catalytic activity of 2D Co0.6/NC-700 is likely ascribed to its 2D leaf-like structure with more accessible dispersed active sites and the interaction between Co NPs and N-doped carbon nanosheets. 2D Co0.6/NC-700 displayed superior oxidase-like activity with a low Michaelis–Menten constant (Km) of 0.35 mM. Interestingly, in the presence of both acetylcholinesterase (AChE) and acetylthiocholine (ATCh), the oxidase-like activity was suppressed because of the generation of thiocholine, which led to the fading of the TMB color reaction. On this basis, a colorimetric assay was developed for the determination of AChE activity. 2D Co0.6/NC-700 displayed excellent detection performance in AChE activity, with a linear detection range of 0.0002–0.8 U L–1 and a low detection limit of 0.0002 U L–1. Remarkably, the method showed good selectivity to AChE, and other coexisting substances had minor interference. The method was satisfactorily utilized to determine the AChE activity in real samples

Role of Interface of Metal–Organic Frameworks and Their Composites in Persulfate-Based Advanced Oxidation Process for Water Purification

The persulfate activation-based advanced oxidation process (PS-AOP) is an important technology in wastewater purification. Using metal–organic frameworks (MOFs) as heterogeneous catalysts in the PS-AOP showed good application potential. Considering the intrinsic advantages and disadvantages of MOF materials, combining MOFs with other functional materials has also shown excellent PS activation performance and even achieves certain functional expansion. This Review introduces the classification of MOFs and MOF-based composites and the latest progress of their application in PS-AOP systems. The relevant activation/degradation mechanisms are summarized and discussed. Moreover, the importance of catalyst-related interfacial interaction for developing and optimizing advanced oxidation systems is emphasized. Then, the interference behavior of environmental parameters on the interfacial reaction is analyzed. Specifically, the initial solution pH and coexisting inorganic anions may hinder the interfacial reaction process via the consumption of reactive oxygen species, affecting the activation/degradation process. This Review aims to explore and summarize the interfacial mechanism of MOF-based catalysts in the activation of PS. Hopefully, it will inspire researchers to develop new AOP strategies with more application prospects