Experimental and theoretical study on one-step synthesis of AuAg alloy nanoparticle catalytic layer as highly stable non-enzymatic glucose sensing interface

Abstract

Au-based non-enzymatic glucose sensor has excellent catalytic performance, but it is difficult to be applied to practice due to high cost. A facile method was developed to load three AuAg alloy nanoparticle catalytic layer on the fluorine-doped tin oxide conductive glass by calcination as the working electrodes for non-enzymatic glucose sensors in a single process. Scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction, and N2-adsorption–desorption were used to characterize the samples. The electrochemical properties of the electrodes were studied by cyclic voltammetry and electrochemical impedance spectroscopy methods. The Au1Ag1 catalytic layer electrode prepared achieved ultra-high detection sensitivity for glucose, and demonstrated excellent stability, maintaining ∼90 % sensitivity after 30 days of storage in room-temperature air. The adsorption properties of various AuAg substrates on glucose molecules under alkaline conditions were investigated using density functional theory. For the same AuAg substrates, the Ag sites adsorbed glucose more strongly than the Au sites. The adsorption capacity of Ag sites on the AuAg substrates is superior to that of Au sites on the Au substrates, which means that the doping of Ag improves the adsorption capacity for glucose, qualitatively supporting the experimental results. Under alkaline synthetic conditions, the AuAg alloying dramatically enhances the sensitivity and stability of the non-enzymatic glucose sensor. Meanwhile, the preparation method of the sensor is simple and the cost is low. This paper provides research ideas and theoretical support for the performance improvement and cost reduction of noble metal-based non-enzymatic glucose sensors.