In-situ reshaping nano-biochar on electrode surface for machine learning assisted selective sensing of Pb 2+ in real water samples

Surface engineering is an indispensable basic means to improve the properties of carbon nanomaterials and expand their application fields. Herein, tea residue was used as raw material to produce nano-biochar (NBC) by thermal decomposition method. Then the NBC was reshaped in situ on electrode surface to obtain electroreduced NBC (ErNBC) by cyclic voltammetry. After related material characterization, it is found that the properties of NBC are ideally reshaped after in situ electrochemical reduction, the size of NBC is reduced, the content of O element is increased, the hydrophilicity of NBC is enhanced, and the conductivity of NBC is improved. A model was constructed synchronously, and theoretical calculations were conducted to verify the changes in the material’s energy gap. Meanwhile, utilizing the structural properties of ErNBC, we develop an electrochemical sensor combined with machine learning for selective detection of Pb 2+ in actual water samples with a satisfactory recovery rate.