Interpenetrating twin ZIF-8/carbon nanofiber aerogel independent electrochemical sensor for the detection of heavy metal ions in soil and crops

Heavy metal ions (HMIs) pollution has become a significant threat to the global environment and agricultural safety. The accumulation of these metals in soil and crops may have a serious impact on human health. Therefore, it is of utmost importance to develop a rapid, reliable and highly sensitive detection platform. A self-supporting electrochemical sensor based on an interpenetrating twin ZIF-8/carbon nanofiber aerogel (ZIF-8(IT)/CNT-NFCA) was developed for the sensitive and simultaneous detection of Cd 2+ and Pb 2+ in soil and crop samples. Unlike traditional electrodes, this independent architecture eliminated the need for rigid conductive substrates and complex surface modifications. The freestanding 3D nanofiber network, reinforced by carbon nanotubes and embedded with twin-structured ZIF-8, provided a mechanically stable and highly conductive matrix with abundant accessible active sites. Under optimized differential pulse anodic stripping voltammetry conditions, the sensor exhibited wide linear ranges of 0.10–100 μg·L −1 for both Cd 2+ and Pb 2+ , with low limit of detection (LOD) 0.09 μg·L −1 and 0.05 μg·L −1 , respectively. Benefiting from the integrated structure, the sensor showed enhanced signal stability and resistance to electrode delamination under real sample testing. Applications in actual rice, wheat, soil, and water samples demonstrated high recovery rates and validated the sensor's reliability. This study provides a robust and portable sensing platform, offering promising prospects for field-deployable heavy metal ion monitoring in environmental and agricultural safety.