Development of CNT thin film electrodes for lead ion sensing: a step toward scalable water quality monitoring

Journal article, 2026

Heavy metal contamination in drinking water is a critical global issue, as even trace levels pose serious health risks. Numerous studies report concentrations of heavy metals exceeding limits set by the WHO and the US-EPA. Electroanalytical sensing technologies have therefore gained importance for rapid, sensitive, and on-site detection of heavy metals. In this work, we present a scalable and industrially viable carbon nanotubes (CNT) film electrode for electrochemical detection of Pb2+ in water. The CNTs grown via chemical vapor deposition were uniformly press-transferred onto PET substrates to create carbon nanotube network thin films (CNT-NTF). This fabrication strategy enables large-area, reproducible, and mass-producible electrodes, addressing a major gap in earlier CNT-based sensors. CNT-NTF sensors achieved sub-nanomolar (ppb) detection limits for Pb2+, with two well-defined linear response ranges and reliable performance across buffer, simulated drinking water, tap water, and river water matrices. The electrode detected Pb2+ at concentrations significantly below WHO and US-EPA limits, while maintaining stable responses across temperatures from 5 to 45 degrees C. Interference studies confirmed robust detection in the presence of As3+ and Cd2+. The combination of low detection limits, stability in realworld samples, and compatibility with large-area fabrication highlights the CNT-NTF platform as a promising route toward scalable and cost-effective monitoring of heavy-metal contamination in water systems.