Electronic modulation caused by interfacial Fe-O-Co-O-Fe bonding for boosting highly efficient non-enzymic nitrite sensing

Rational electronic modulation of metal–organic frameworks (MOFs) derived electrocatalysts is an effective strategy for rendering them capable of enhanced sensing performance, but rather challenging. Herein, we propose a combination strategy of self-templated transformation and carbonization pyrolysis for elaborately synthesizing a MOF-derived non-planar FeCo hierarchical nest-like networks (n-FeCo-HNNs) heterojunction catalyst. Owing to the excellent electrical conductivity and active site density of n-FeCo-HNNs, such non-enzymic nitrite sensor displays a wide broad detection range, excellent sensitivity, and ultralow limit of detection. Experimental and theoretical calculations clarified the electrons are extracted and rapidly transferred to the surface-active sites through the Fe-O-Co-O-Fe bridge, and then improve the reaction kinetics and boost the sensing performance for nitrite. The synergistic effect of this chemical bond established in the heterostructure unveils a new avenue for efficient electrochemical sensing.