Yuan Qin,Huimei Liang,Jia Wu,Zheyang Chi,Shulin Zhao,Fanggui Ye
Natural enzyme cascades, including the same and different kinds of enzymes, have been widely used in biosensing. However, it is still a challenge for nanozymes, the mimics of natural enzymes, to achieve biosensing with different types of enzyme-like activities based on cascade reactions, such as hydrolase and oxidoreductase. Considering the characteristics of the multienzyme-like activity of some nanozymes, as a proof of concept, this study demonstrates a Cu/Ce-MOF-808 nanozyme as a self-cascade catalyst with hydrolase-like and catechol oxidase-like activities. Taking organophosphorus pesticides as an example, we constructed a self-cascade catalytic reaction for the one-step colorimetric detection of isocarbophos. Specifically, the hydrolase-like activity of Cu/Ce-MOF-808 can hydrolyze isocarbophos to produce colorless isopropyl salicylate, which is further oxidized by the catechol oxidase-like activity of Cu/Ce-MOF-808 and complexed with 4-aminoantipyrine (4-AAP) to produce red quinoneimine under neutral conditions with illumination. Thus, a colorimetric strategy for sensitive isocarbophos analysis is developed, with a linear range of 0.90–400.00 μg·mL–1 and a detection limit of 0.42 μg·mL–1. This research presents a new approach to the design and synthesis of nanozymes and has great application potential in the field of nanozyme cascade biosensing.
Herein, a novel hydrothermal synthesis strategy is proposed for the preparation of novel Cu-Ce MOF heterojunction nano catalysts (CuCeO X /C) for 5-hydroxymethylfurfural (HMF) electrooxidation reaction in this paper. CuCeO X /C exhibits superior catalytic performance, with the current density of CuCeO X /C reaching 100 mA cm −2 at a low potential of 1.408 V vs. RHE, and doubling to 280 mA cm −2 at a lower potential of 1.5 V vs. RHE. Under these conditions, the conversion of HMF reaches 100 %, with a selectivity of over 99.11 % for 2,5-furan dicarboxylic acid (FDCA) and a Faradaic efficiency of 97.76 %. Theoretical calculations and In-situ-EIS have demonstrated that Ce-based Cu-MOF heterojunction nanocatalysts enhance the adsorption energy of the CuCeO X /C catalysts on HMF substrates while also decreasing reaction energy barrier of HMFOR. Based on our work, the employment of CeCu/MOF heterojunction electrocatalysts for efficient electro-oxidation of HMF to FDCA paves a green and sustainable way for advancing sustainable chemical processes and biomass valorization.
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