Fe-doping-driven enhancement of electronic conductivity and electrocatalytic performance in Gd2O3 nanoparticles for ultrasensitive electrochemical detection of chloramphenicol in pharmaceutical and milk samples

Abstract

In this study, Gd₂O₃ and Fe-doped Gd₂O₃ NPs were synthesized via a thermal decomposition method and integrated into an electrochemical sensing platform to systematically investigate the impact of Fe doping on the electronic conductivity and electrocatalytic performance toward sensitive chloramphenicol (CAP) detection. The structural, morphological, and compositional properties of the Gd₂O₃ and Fe-doped Gd₂O₃ NPs were characterized using FE-SEM, TEM, and VSM techniques. Fe doping significantly enhances the electrical conductivity and the electrochemically active surface area, which was confirmed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. Fe-doped Gd₂O₃ exhibits improved electrocatalytic activity, significantly lowering the activation energy for the CAP electrochemical reduction reaction, as evidenced by linear sweep voltammetry (LSV) and chronoamperometry (CA) measurements. Owing to the aforementioned synergistic contributions, the Fe-doped Gd₂O₃-based electrochemical nanosensor demonstrated remarkable analytical performance in a wide dynamic concentration range with a high electrochemical sensitivity of 1.010 µA µM⁻¹ cm⁻², a low detection limit of 0.25 µM, excellent repeatability, strong anti-interference ability, and good storage stability. The Fe-doped Gd₂O₃ demonstrated strong potential for CAP detection in pharmaceutical formulations and milk samples with a recovery ranging from 94.1 to 114.0%. The results suggested that the Fe-doped Gd₂O₃ NPs hold great potential for the development of an on-site and point-of-care analytical device for pharmaceutical quality control and antibiotic residue detection in food products.