Electrochemical Sensor Based on Porous Biochar-Loaded MnO₂ Nanocomposite for Sensitive Detection of Cd(II)

Understanding the extent of cadmium (Cd) contamination and its impact on the food industry and ecosystems is crucial; to this end, electrochemical methods provide sensitive and rapid responses for the in situ detection of heavy metal ions. In this paper, a sensitive Cd²⁺ electrochemical sensor was constructed by using a composite material composed of biomass-derived porous carbon and manganese dioxide (MnO₂/KLSC). The composite was demonstrated to have a porous structure with quasi-cubic MnO₂ particles evenly distributed on the carbon matrix. Using MnO₂/KLSC as the electrode material, a simple electrochemical sensing platform was fabricated for the detection of Cd²⁺. The electrochemical analysis showed that the Cd²⁺ sensor has good performance, with a linear detection range of 0.01-80.0 μmol/L and a detection limit of 9.8 nmol/L. Furthermore, the sensor shows excellent repeatability, reproducibility, and good anti-interference. The sensor was successfully applied to analyze rice and sea water samples, demonstrating satisfactory recovery rates. The good performance of MnO₂/KLSC/GCE can be attributed to the excellent electrical conductivity, enlarged active surface area, and good electron transfer capability.