Au–Cu Ratio Optimization In Co-Deposition For Superior Electrochemical Glucose Sensing On Screen-Printed Graphene Electrodes

Abstract

This study explores the influence of the gold (Au) ratio in Au-Cu co-electrodeposition on the electrochemical performance of a screen-printed graphene electrode (SPGE) for glucose sensing. By varying the Au content in the Au-Cu alloy, the electrode's current response was evaluated across five glucose concentrations: 55 nM, 110 nM, 165 nM, 220 nM, and 275 nM. The aim was to identify the optimal Au-Cu composition that enhances electron transfer and overall electrochemical activity. The experimental results revealed a non-linear relationship between Au ratio and current response. The most significant enhancement in current was observed at an Au ratio of 0.50, where the signal increased by approximately 100–250% compared to other compositions. This enhancement is attributed to the formation of a balanced Au-Cu alloy, which promotes efficient charge transfer, improved conductivity, and stable surface morphology. At lower Au ratios, excessive Cu content may lead to poor structural integrity and reduced catalytic activity, whereas higher Au ratios result in insufficient Cu to support the alloy’s catalytic synergy, causing diminished current response. These observations confirm that the Au-Cu alloy composition plays a critical role in determining the electrode's electrochemical behavior. This work demonstrates that an Au ratio of 0.50 in Au-Cu co-deposition yields the most favorable electrochemical characteristics, making it a promising candidate for non-enzymatic glucose sensors, biosensors, and other electrocatalytic applications.