A highly selective mercury ion electrochemical detection based on the enhancement of oxidase-like activity by mercury on electrodeposited palladium nanoparticles@reduced graphene oxide

Abstract

As the toxic mercury ions (Hg²⁺) widely present in rivers and soil threaten human health, it is essential to develop various methods to detect and monitor Hg²⁺. At present, increasing numbers of nanozymes with peroxidase-like or oxidase-like activity have been exploited to develop the colorimetric detection of Hg²⁺. However, research on the electrochemical detection of Hg²⁺ by nanozymes is still rarely reported. Herein, on the basis of our previous research on palladium-based nanozymes with oxidase-like activity, graphene and palladium nanoparticles (PdNPs) were electrochemically deposited on the electrode surface. Then, the enhancement effect of palladium–mercury binding on the oxidase-like activity of electrodeposited PdNPs was studied for the first time. Moreover, it was found that only Hg²⁺ can enhance the catalytic oxidation of TMB compared to other common metal ions. Based on these properties, a highly selective, convenient and eco-friendly electrochemical Hg²⁺ sensor has been successfully developed, which has a wide linear range of 1.0–40 μM and a low LOD of 0.33 μM. Additionally, the proposed method shows acceptable recovery in real sample tests, indicating promising prospects in the field test and water pollution monitoring of Hg²⁺.