In the present study, an innovative electrochemical sensing platform was established for sensitive detection of NO2 —. This sensor was developed using CoFe alloy encapsulated in nitrogen-doped carbon nanocubes (named as CoFe@NC-NCS), synthesized through the calcination of polydopamine-coated CoFe Prussian-blue analogues (CoFe-PBA@PDA). The morphological and electrochemical characterization reveals that the CoFe@NC-NCS possesses high electrocatalytic activity for electrochemical quantitation of NO2 —, ascribed to the huge surface area and plentiful active positions, benefiting from the porous, hollow, and core–shell structure of CoFe@NC-NCS. Under the optimal conditions, CoFe@NC-NCS/GCE possessed remarkable sensing performance for NO2 — with wide liner ranges and a detection limit of 0.015 μM. NO2 — recovery experiments in real samples exhibited recoveries in the range of 98.8–103.5%. Hence, the CoFe@NC-NCS shows great promise for the construction of electrochemical sensor with more potential application.

A high sensitivity strategy of nitrite detection based on CoFe@NC nanocubes modified glassy carbon electrode
    Abstract
    1 Introduction
    2 Experimental section
        2.1 Reagents
        2.2 Synthesis of CoFe@NC nanomaterials with different morphologies
        2.3 Construction of the various GCEs
        2.4 Instruments
        2.5 Sample preparation
    3 Results and discussion
        3.1 Characterization of CoFe@NC with different morphologies
        3.2 Electrochemical detection applications
    4 Conclusions
    Acknowledgements 
    References

• Yanjiao Zou(School of Chemistry and Environmental Engineering, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan 430073, China)
• Hongfei Gu(School of Chemistry and Environmental Engineering, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan 430073, China)
• Jingjing Yang(School of Chemistry and Environmental Engineering, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan 430073, China)
• Ting Zeng(School of Chemistry and Environmental Engineering, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan 430073, China)
• Juan Yang(School of Chemistry and Environmental Engineering, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan 430073, China)
• Yuanyuan Zhang(School of Chemistry and Environmental Engineering, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan 430073, China)