Heterointerface-engineered CuO/Cu2O/C sensitive electrode for electrochemical detection of nitrite

Nitrite is a widespread contaminant in environmental and food systems, and its excessive intake poses significant risks to human health, creating an urgent need for sensitive and robust detection technologies. The performance of conventional electrochemical sensors is often limited by the limited conductivity, aggregation tendency, and interfacial instability of copper-oxide-based materials. A CuO/Cu 2 O/C composite electrode was developed through controlled thermal treatment, where mixed-valence copper oxides are integrated into a conductive carbon framework to address these intrinsic limitations. The optimized CuO/Cu 2 O/C electrode exhibits outstanding electrocatalytic performance toward nitrite oxidation, delivering a broad linear range (2 μM–5000 μM), high sensitivity (52.32 μA μM −1  cm −2 ), and a low detection limit (0.101 μM). The results indicate that the prepared CuO/Cu 2 O/C composite material promotes charge separation and transfer through the heterojunction interface, utilizing the Cu 2+ /Cu + redox couple to provide abundant active sites. Moreover, the carbon substrate not only improves conductivity, inhibits particle aggregation, and increases the electrochemical active area, but also optimizes the oxidation state of copper to the Cu 2+ /Cu + redox pair. These findings provide a promising materials platform and meaningful guidance for the rational design of copper-oxide-based composites tailored for high-performance electrochemical sensing.