Construction of Zn-BDCNPs/Au-NCs heterojunction electrochemical sensor and its application in nitrite detection

Background The exploitation of rapid and efficient electrochemical sensors for small inorganic molecules detection is crucial for environment assessment and health surveillance. Pristine metal-organic frameworks (MOFs) display low intrinsic conductivity, and common noble-metal materials suffer from particle agglomeration and high nitrite oxidation potential. Developing high-performance heterostructures for trace nitrite sensing thus remains challenging. Methods In this study, we integrated Au nanoclusters (Au-NCs) into zinc-based metal–organic framework nanopieces (Zn-BDC NPs) to form a novel zinc-based metal–organic framework nanopieces/Au nanoclusters (Zn-BDC NPs/Au-NCs) heterojunction nanocatalyst, which was then applied to the electrochemical detection of nitrite. Au-NCs can compensate for the insufficient conductivity of Zn-BDC NPs, thereby accelerating electron transfer. Combined Density Functional Theory (DFT) calculations reveal that the heterojunction achieves favorable nitrite adsorption energy, which enriches exposed active sites and significantly lowers nitrite oxidation potential. Significant Findings The Zn-BDC NPs/Au-NCs sensor achieves a sensitivity of 116.8 μA/(mM·cm²), a detection limit of 70 nM, and a linear range of 0.7–833.5 μM for nitrite detection. This provides new candidate materials for the precise and efficient detection of nitrite in environmental waters.