Electrochemical Sensor Based on Acetylene Black-Modified Two-Dimensional Metal–Organic Framework [Cd ₂ (BPDC) ₂ (1,4-bis) ₂ ] <i> _n </i> /AB for Efficient Detection of NO ₂ ^–

Excessive nitrite poses potential threats to human health, making the convenient and accurate detection of nitrite anions (NO₂^-) critically important for practical applications. Two-dimensional (2D) metal-organic frameworks (MOFs) have attracted attention in the design and application of electrochemical sensors due to their unique structure. In this work, based on the 2D [Cd₂(BPDC)₂(1,4-bis)₂]<i>_n</i> (MOF1, 4,4'-biphenyldi-carboxylic acid = H₂BPDC, 1,4-bis(imidazol-1-ylmethyl)-benzene = 1,4-bis) and acetylene black (AB), a novel electrochemical AB/MOF1/glassy carbon electrode (GCE) sensor is constructed and demonstrated for sensitive detection of NO₂^- in the solution. The research demonstrates that the AB/MOF1/GCE electrochemical sensor exhibits a wide linear response range (2-200 μM) and a low detection limit (5.7093 × 10^-8 M), attributable to the synergistic effect of the selectivity contributed by the 2D MOF1 structure and the enhanced sensitivity provided by the AB. It demonstrated excellent selectivity, long-term stability, and reproducibility and can be successfully used for the detection of nitrite in actual samples with a recovery rate of 95.35-104.94%. This paper provides the synthetic application of electrochemical sensors and an effective detection method for carcinogen NO₂^- in the environment.