An ultrasensitive electrochemical method for rapid detection of mercury based on nanoporous gold capped with a novel Zr-MOF-SH/reduced graphene oxide aerogel composites.

In this work, an ultrasensitive electrochemical sensor based on Zr-MOF-SH/rGA/NPG was developed for the first time for the rapid determination of mercury ions. First, nanoporous gold (NPG) film was covered on the glassy carbon electrode (GCE) to offer a desirable substrate. Then, Zr-MOF-SH/rGA composites were dropped on the NPG film to form a modified electrode. Mercapto functionalized MOFs (Zr-MOF-SH) showed strong adsorption capability toward mercury ions, and the unique structure of reduced graphene oxide aerogel (rGA) provided various sites for coupling with Zr-MOF-SH as well as improved the electrochemical activity. As a consequence of the synergistic effect of Zr-MOF-SH, rGA, and NPG, the optimized Zr-MOF-SH/rGA/NPG/GCE sensor showed excellent detection performance toward mercury ions with a linear range from 0 to 200 nM and a low limit of detection of 1.4 nM. Meanwhile, the fabricated electrochemical sensor exhibited outstanding stability, reproducibility, and anti-interference ability. To verify the practical applicability, the Zr-MOF-SH/rGA/NPG/GCE was applied for the determination of mercury ions in real rice samples with desirable recovery rates ranging from 98.8% to 108.3%.