Picomolar detection of mercury (II) using a three-dimensional porous graphene/polypyrrole composite electrode.

A polypyrrole (PPy)-functionalized three-dimensional (3D) porous electrode of electrochemically reduced graphene oxide (ErGO) has been prepared by electrochemical deposition. This PPy-modified 3D-ErGO electrode was used for the electrochemical detection of Hg(2+) ions, and it exhibited high sensitivity and selectivity. Furthermore, the limit of detection (LOD) was measured to be as low as 0.03 nM (30 ppt), and this value is much lower than the guideline value of 2 ppb for drinking water given by the World Health Organization.