Highly sensitive hydrogen sensors: Pd-coated Si nanowire arrays for detection of dissolved hydrogen in oil

We studied the H-2 sensing properties of Pd nanoparticles on vertical standing Si nanowire (NW) arrays for the detection of dissolved hydrogen (H-2) gas in transformer oil. The Pd-coated Si NW arrays were fabricated by using the aqueous electroless etching method and sputtering. The Pd-coated Si NW arrays were immersed and measured in transformer oil with various dissolved concentrations of H-2. We found that Pd-coated Si NW arrays showed significantly superior performance with regard to the response (similar to 1000%), the lowest detection limit (1 ppm), and the response time (600 s). The Pd-coated Si NW arrays showed a temperature coefficient of resistance (TCR) of 6.53 x 10(-3) degrees C-1 at various oil temperatures (20-80 degrees C). Pd-coated Si NW arrays showed good reliability for the detection of H-2 in oil at room temperature (20 degrees C), with nearly the same initial resistance for 30 days.