ZIF derived coral-like hierarchically structured CoO@CoMn-LDH nanoarray self-supported electrocatalyst for enhanced formaldehyde electrochemical sensing in food samples

Formaldehyde (FA) is a toxic substance and represents a risk to human health. It is urgent to develop a low-cost and sensitive electrochemical detection technology for FA based on inexpensive transition metal nanomaterials. In this work, using Co(OH)F nanorods and ZIF-67 as precursors, a self-supporting coral-like CoO@CoMn-LDH nanoarray electrocatalyst with hierarchical structure was synthesized in situ on nickel foam (NF) substrate by two-step template strategy. The integration of hierarchically structured LDH onto the conductive nickel foam substrate offers a robust solution to the disadvantages of low electrical conductivity and easy agglomeration of LDH. Consequently, the engineered coral-like nanoarray significantly enhances the specific surface area and density of active sites of the electrocatalyst, while also facilitating an improved electron transport rate and enhanced mass transfer capacity. As a working electrode, the FA sensor shows superior electrochemical detection performance with a wide response linear range (0.035–7 mM) and a low detection limit (7.8 ×10⁻³ mM (S/N = 3)), and it has also been effectively utilized to measure FA concentrations in real food samples. This study offers a novel approach and method for developing an efficient and sensitive electrochemical detection technology for FA.