Reversible chemiresistive sensing of ultra-low levels of elemental mercury vapor using thermally reduced graphene oxide.

A chemiresistor sensor for ultra-low levels of elemental mercury (Hg0) vapor is described. The sensor was prepared through thermal reduction of graphene oxide (GO) deposited on an interdigitated electrode using only low temperature annealing typically at 230 °C. The sensor responds to the presence of Hg0 vapor within <1 min and spontaneously recovers its baseline through flushing with a Hg0-free carrier gas. The sensor has a linear response in the range of 0.5 to 12.2 ppbv of Hg0 vapor and a detection limit of 0.10 ppbv. The amount of GO and annealing temperature affect the sensor response and were optimized. The sensor can find use in monitoring exposure of persons to Hg0 vapors, for which a threshold value of 6.1 ppbv has been set by the World Health Organization. Graphical abstract Schematic of an interdigitated electrode modified with a layer of thermally reduced graphene oxide. It can be used as a chemiresistive sensor for Hg0 vapor. The sensor displays a rapid and reversible response and has an ultralow detection limit of 0.10 ppbv.