Highly efficient electrochemical gas reduction on a three-dimensional foam electrode: mechanism and application for the determination of hazardous mercury in complex matrix.

For the first time a nickel foam electrode (NFE) is applied in the field of electrochemical vapor generation (EVG) to carry out the electrochemical vapor phase conversion of mercury. Systematical electrochemical and morphological research has demonstrated that the specific surface area of the NFE was several times larger than that of the metal/non-metal electrode with the same geometric size. At the same time, the 3D porous channel composed of multi-layer nickel wire ensures the full contact between reactant and interface. The evident enhancement of spectral signals on a Ni electrode (283%), compared with Pt (27%) and graphite (109%), confirmed that the NFE effectively enhances the yield of mercury reduction. The NFE exhibits low limit of detection (0.017 μg L) and a wide linear range (0.2-20 μg L) with recoveries of actual samples in the range 87.8-117% towards Hg. Although the NFE has no advantage in electronic transmission and catalytic performance, its excellent stability, especially anti-interference and other characteristics, is sufficient for the analysis of hazardous mercury in complex matrix including certified reference materials and real samples.