Axial N Ligand‐Modulated Ultrahigh Activity and Selectivity Hyperoxide Activation over Single‐Atoms Nanozymes

Abstract

Learning and studying the structure–activity relationship in the bio‐enzymes is conducive to the design of nanozymes for energy and environmental application. Herein, Fe single‐atom nanozymes (Fe‐SANs) with Fe–N 5 site, inspired by the structure of cytochromes P450 (CYPs), are developed and characterized. Similar to the CYPs, the hyperoxide can activate the Fe(III) center of Fe‐SANs to generate Fe(IV)=O intermediately, which can transfer oxygen to the substrate with ultrafast speed. Particularly, using the peroxymonosulfate (PMS)‐activated Fe‐SANs to oxidize sulfamethoxazole, a typical antibiotic contaminant, as the model hyperoxides activation reaction, the excellent activity within 284 min −1 g −1 (catalyst) mmol −1 (PMS) oxidation rate and 91.6% selectivity to the Fe(IV)=O intermediate oxidation are demonstrated. More importantly, instead of promoting PMS adsorption, the axial N ligand modulates the electron structure of FeN 5 SANs for the lower reaction energy barrier and promotes electron transfer to PMS to produce Fe(IV)=O intermediate with high selectivity. The highlight of the axial N coordination in the nanozymes in this work provides deep insight to guide the design and development of nanozymes nearly to the bio‐enzyme with excellent activity and selectivity.

Perspectives for the Role of Single-Atom Nanozymes in Assisting Food Safety Inspection and Food Nutrition Evaluation

“…In addition, introducing substrate binding ligands like antibodies and aptamers was proved to be one of the efficient ways to improve the specificity. 94 The molecularly imprinted polymers method was also expected to be another way to improve the selectivity. (4) Combining SAzymes with various cutting-edge technologies, such as electrochemistry, enzyme-linked immunoassay, lateral flow immunoassay, colorimetric assay, fluorescence assay, etc., could make full use of the advantages of SAzymes and thus actually broaden the applicability mode of SAzymes in food testing.…”

“…The axial N ligand was beneficial to lower the energy barrier and accelerate electron transfer, which was greatly helpful for intermediate generation with high selectivity. In addition, introducing substrate binding ligands like antibodies and aptamers was proved to be one of the efficient ways to improve the specificity . The molecularly imprinted polymers method was also expected to be another way to improve the selectivity.…”

Single-Atom Nanozyme Based on Mn-Center with Enhanced Peroxidase-like Activity for Organic Dye Degradation

“…The results are shown in Figure 3h,i The experimental results show that the doping of Mn can greatly improve the POD-like activity of nanozymes in the catalytic process. Related research shows that the P atom can be used as the binding point of the substrate and the intermediate in the reaction process, 41 which optimizes the reaction process and reduces the activation energy. The doping of the S atom can be used as an adsorption site to stabilize the intermediate of ROS and enhance the enzyme-like activity.…”

“…Since the emergence of single-atom nanozymes, numerous reports have been made on single-atom nanozymes. They mainly focus on sensing and detection − and biomedicine, − and there are relatively few studies on dye degradation. , Single-atom catalysts can greatly reduce the use of precious metals because of their high atomic utilization, which is a great help for cost control. In the field of nanozymes, there are more research studies on manganese oxides, but there are few studies on single-atom nanozymes with manganese as the metal center, mostly with the coordination structure of Mn and N, and the effects of other heteroatom doping on the activity of manganese-based nanozymes need to be further studied.…”

Single-Atom MnN5 Catalytic Sites Enable Efficient Peroxymonosulfate Activation by Forming Highly Reactive Mn(IV)–Oxo Species

“…The coordination number of M–N moieties in SACs strongly affects the geometric and electronic properties, as well as the catalytic activity of SACs. While SACs with a coordination number higher than four have been used for selective conversion of hydrocarbons and oxygen reduction reactions − and play prominent roles in biomimetic and enzymatic oxidation reactions, − the five-nitrogen coordinated SACs are seldom explored for persulfate activation except for Fe–N 5 SACs. , This represents a fundamental knowledge gap and a missed opportunity for coordination chemistry using other transition metal SACs (such as Co, Mn, Cu, and Ni) to boost PMS activation and enhance the degradation of recalcitrant organic pollutants. For instance, while Mn SACs have been tested for HVMO-dominated persulfate activation, five-nitrogen coordinated Mn SACs have not.…”