High-Performance Mesoporous Carbon@Dopamine Nanocomposite Sensor for Simultaneous Detection of Heavy Metal Ions in Environmental Monitoring

Heavy metal ion (HMI) sensors are critical tools for environmental monitoring, given the severe health risks associated with HMI overdosage. In this study, a high-performance mesoporous carbon@dopamine (MC@PDA) nanocomposite was developed as an efficient material for constructing a smart sensor capable of the simultaneous electrochemical detection of Cd²⁺, Cu²⁺ and Hg²⁺ ions. To investigate the role of template material, different electrocatalysts, such as CNT@PDA, CNH@PDA, and MC@PDA were compared. While all C@PDA materials exhibited electroactivity for HMI detection, mesoporous carbon (MC) demonstrated superior electrochemical activity due to its hierarchical micro-/mesoporous nanoarchitecture, optimized pore volume, and high surface area, which support enhanced electron transport, superior adsorption, catalytic activity, and functionalization. The MC@PDA exhibited improved peak currents over a wide large linear range of 100 nM-1.4 mM for the simultaneous detection of Cd²⁺, Cu²⁺ and Hg²⁺, with limit of detections (LODs) of 63, 122, and 82 nM, respectively. For individual ion detection, the sensor achieved even lower LODs of 8.34, 4.36, 6.172 nΜ for Cd²⁺, Cu²⁺ and Hg²⁺, respectively. Density functional theory (DFT) calculations were performed to unravel the distinct interaction mechanisms and energy variations between PDA and HMI. Moreover, the sensor was deployed for real-world water analysis from an industrial mining site with multiple contaminants, effectively detecting Cd²⁺, Cu²⁺ ions. Results were validated using atomic absorption spectroscopy (AAS), confirming the method's reliability and practical applicability. The suggested technique will enable simultaneous detection of multiple analytes and uses interactive forces to efficiently distinguish analogue analytes.