Trace Detection of Dissolved Hydrogen Gas in Oil Using a Palladium Nanowire Array

The electrical resistance, R, of an array of 30 palladium nanowires is used to detect the concentration of dissolved hydrogen gas (H(2)) in transformer oil over the temperature range from 21 to 70 degrees C. The palladium nanowire array (PdNWA), consisting of Pd nanowires similar to 100 nm (width), similar to 20 nm (height), and 100 mu m (length), was prepared using the lithographically patterned nanowire electrodeposition (LPNE) method. The R of the PdNWA increased by up to 8% upon exposure to dissolved H(2) at concentrations above 1.0 ppm and up to 2940 ppm at 21 degrees C. The measured limit-of-detection for dissolved H(2) was 1.0 ppm at 21 degrees C and 1.6 ppm at 70 degrees C. The increase in resistance induced by exposure to H(2) was linear with [H(2)](oil)(1/2) across this concentration range. A PdNWA sensor operating in flowing transformer oil has functioned continuously for 150 days.