Bi₂O₂Se nanosheets for dual-mode electrochemical/fluorescence turn-off sensing of ferric ions

This study investigates a novel dual electrochemical and fluorescence turn-off sensing approach for the selective detection of ferric ions (Fe³⁺) using exfoliated Bi₂O₂Se nanosheets (Ex-BOSe NSs), a new type of non-van der Waals 2D material with excellent optical, electronic, and functional properties. These ultrathin BOSe NSs were synthesized via a facile chemical method and exfoliated to increase the density of surface active sites and improve photoluminescence response. They were characterized structurally, optically, and morphologically, confirming the desired material properties. The resulting electrochemical sensor exhibited high sensitivity (411 μA μM^-1 cm^-2) and selectivity for Fe³⁺, while the nanosheets concurrently demonstrated significant photoluminescence quenching in the presence of Fe³⁺ (detection limit: 110 nM, range: 200 nM-1 mM). Computational analysis supported the selective adsorption of Fe³⁺, highlighting the potential of the combined electrochemical and fluorescence sensing capabilities of exfoliated Bi₂O₂Se nanosheets for cost-effective, real-time, and portable heavy metal ion detection.