Biomass-derived nano-black carbon film electrode for the electrochemical detection of hazardous ions

In this study, sweetgum fruit, a type of biomass, is used as a raw material to produce compact and uniform carbon films on an alumina substrate by chemical vapor deposition. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy results reveal that the carbon film fabricated at 950 °C comprises nano-black carbon, particularly in the form of nanosheets and nanotubes. Furthermore, electrochemical impedance spectroscopy and cyclic voltammetry results confirm that the film exhibits good electrochemical properties. X-ray photoelectron and Raman spectroscopies were conducted to analyze the chemical bonds of the as-obtained nano-black carbon films. The as-obtained carbon film attached to the alumina substrate was employed as the working electrode, and an electrochemical sensor was designed for the detection of hazardous ions, such as Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺. After parameter optimization, various metal ions with different concentrations were detected through differential pulse anodic stripping voltammetry using a nano-black carbon film electrode. The resulting peak currents correlated with the metal ion concentrations. The detection limits were determined to be 21.1, 7.72, 3.85, and 1.68 nM for Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺, respectively. An interference study was conducted by adding common ions and examining real water samples containing certain amounts of Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺. Promising results were obtained during the recovery experiment, suggesting that the proposed sensors have potential applications in environmental monitoring.