Colorimetric/electrochemical dual mode detection ascorbic acid based Au@PdNi nanozyme

The low activity of nanozymes poses a significant scientific challenge, limiting their application. Developing noble metal-based nanozymes with high activity is considered as an effective strategy to address this issue. In this study, core–shell Au@PdNi was synthesized by co-precipitating Pd2+ and Ni2+ on Au cores. The oxidase (OXD)-like property of Au@PdNi was thoroughly investigated, revealing a specific activity reaching 194.2 U mg−1. The high OXD-like activity was attributed to several factors elucidated through experimental analysis and Density Functional Theory (DFT) calculations. Firstly, the core–shell structure of Au@PdNi provides a substantial surface area for catalytic reactions. Secondly, the presence of nickel enhances the current density of the material, augmenting its catalytic activity. Lastly, the electronic interplay between the Au core and the PdNi shell layer improves the binding and reaction kinetics with the target substrate. The Au@PdNi nanozyme demonstrated remarkable performances in colorimetric and electrochemical detection of ascorbic acid (AA), exhibiting high sensitivity and selectivity. Moreover, a portable electrochemical sensor was fabricated for the determination of AA in spiked fruit samples, demonstrating satisfactory recovery rates in real sample analysis.