Bimetallic-MOF-derived crystalline-amorphous interfacial sites for highly efficient nitrite sensing

Considering the importance of rapid and effective detection of nitrite in food samples, herein, we report a multistep heterophase synthetic strategy for constructing crystalline-amorphous zinc/cobalt iron porous nanosheets (C-A Zn/Co-Fe PNSs) on carbon cloth. Notably, the C-A Zn/Co-Fe PNSs@CC electrochemical interface consists of interlaced carbon fibers with many uniformly distributed hybrid nanosheets containing crystalline-amorphous interfacial sites. This particular hybrid structure permits local enrichment of nitrite for enhanced nitrite capture efficiency, laying a solid foundation for the ultrasensitive detection of nitrite. In proof-of-concept experiments, we verified that C-A Zn/Co-Fe PNSs@CC could be used to analyze nitrite with good sensitivity and reproducibility. It is worth mentioning that an ultra-low LOD of 0.44 μM was obtained for the detection of nitrite. The designed electrochemical sensor worked well in complex samples such as sausages and tap water under optimal parameters.