Electrochemical determination of hydrogen sulfide at carbon nanotube modified electrodes

Carbon nanotube (CNT) modified glassy carbon electrodes exhibiting a strong and stable electrocatalytic response towards sulfide are described. A substantial (400 mV) decrease in the overvoltage of the sulfide oxidation reaction (compared to ordinary carbon electrodes) is observed using the CNT-modified electrode, with oxidation starting at ca. -0.3 V (versus Ag/AgCl; pH 7.4). The CNTcoated electrodes thus allow highly sensitive, low potential (+0.1 V), stable amperometric sensing. A wide linear dynamic range (1.25–112.5 (mu)M) was achieved with a detection limit of 0.3 (mu)M (9 ppb). The enhance sensitivity is coupled to an improved stability. Such ability of carbon nanotubes to promote the sulfide electron-transfer reaction suggests great promise for miniaturized sensors for hydrogen sulfide.