Ultrathin NiSe2/Co3Se4 heterojunction nanosheets for electrochemical detection of foodborne formaldehyde.

Formaldehyde, a known carcinogen, has been used illegally as a multipurpose food ingredient. However, unapproved use poses serious health risks, necessitating rapid food safety detection. Electrochemical sensing has emerged as a viable platform for formaldehyde detection and analysis because of its straightforward operation and high sensitivity. In this paper, we propose a plasma-assisted nanostructure method to prepare selenium-rich NiSe2/Co3Se4 heterointerfaces (NiSe2/Co3Se4@N-C) in ultrathin N-doped carbon matrix using NiCo-MOF precursors synthesized by dielectric blocking discharge (DBD) microplasma and selenation process. Three synergistic mechanisms are integrated into the hierarchical architecture: conductive carbon scaffolds creating electron highways, selenium vacancies enhancing reactant adsorption through localized electron enrichment, and heterojunctions facilitating interfacial charge transfer via built-in electric fields. The sensor has remarkable analytical capabilities, including a sub-ppm detection limit (3.94 μM), linear range (8-500 μM), and high stability. The defect-engineering and heterostructure design paradigm open new possibilities in food safety monitoring.