Surface Functionalized Vapor Grown Carbon Fiber Supported Dysprosium Stannate Composites for the Enhanced Detection of Furaltadone: A Synergy of DFT Modeling and Experiment

Abstract

Pyrochlore-type dysprosium stannate (Dy2Sn2O7) has been recognized as a strong spotlight due to its strong catalytic activity, oxygen vacancies, and unique nanoscale structure; however, its low intrinsic electrical conductivity limits direct electrochemical performance. To address this, Dy2Sn2O7 (DySnO) was intercalated into conductive carbon networks, such as polydopamine functionalized vapor-grown carbon fibers (VGCF), which provide excellent electron transport and efficient ion diffusion. In this hybrid, DySnO contributes high catalytic activity through oxygen vacancies and redox-active sites, while VGCF enhances charge transfer, resulting in a synergistic architecture that significantly boosts electrochemical sensing performance. Detailed structural, morphological, and physicochemical investigations validated the successful formation of the DySnO@VGCF nanocomposite. Differential pulse voltammetry (DPV) studies exhibited an ultrasensitive detection of furaltadone (FLD) with a low detection limit (5.3 nM), high sensitivity (1.10 μAμM-1cm-2), and a wide linear dynamic range (0.05 to 936μM), along with excellent selectivity, repeatability, and long-term stability. Additionally, density functional theory (DFT) calculations were performed to elucidate the electronic behavior of the FLD molecule and its interaction with the DySnO surface. Adsorption analyses indicated that the metal-terminated surface exhibits the strongest affinity toward FLD. The most stable adsorption configuration reveals a pronounced interaction between the nitro functional group of FLD and the Dy atom on the DySnO surface, in good agreement with the experimental findings. In summary, the DySnO@VGCF modified electrode, prepared through a simple hydrothermal approach, offers a robust platform for developing highly sensitive electrochemical sensors capable of detecting FLD at nanomolar concentrations in aqueous media and human biological samples.