Magnetic Biochar-Based Electrocatalytic Sensor for Sensitive Detection of Trace Pb2+ in Water

Abstract

Monitoring Pb²⁺ levels is essential for aquatic environmental safety. Compared to conventional methods, electrochemical sensors offer a low-cost and efficient alternative for trace heavy metal analysis, with electrocatalytic sensing strategies playing a key role in signal amplification. While biochar (BC) is a promising electrode modifier due to its porous structure and surface functionalization, its application is often restricted by low conductivity. Herein, magnetic biochar (MBC) was prepared via co-precipitation and utilized to fabricate a modified glassy carbon electrode (MBC/GCE). Characterization of MBC revealed an excellent pore structure and a specific surface area of 120 m²/g, markedly higher than that of BC. This increased surface area offers abundant active sites for the adsorption and preconcentration of Pb²⁺ ions, significantly enhancing the subsequent electrocatalytic reduction process. Electrochemical characterization, including electrocatalytic activity evaluation, showed that the MBC/GCE substantially decreased charge transfer resistance and promotes the redox kinetics of Pb²⁺. Under optimized conditions, the platform exhibited high sensitivity toward Pb²⁺ within a linear range defined by I = 6.34 + 64.5C (R² = 0.996), achieving a detection limit of 68 nmol/L. These results highlight the potential of MBC/GCE as an effective electrocatalytic sensing platform for Pb²⁺ monitoring in water.