Enhanced hydrogen sensing properties of Pd-coated SnO2 nanorod arrays in nitrogen and transformer oil

We report enhanced sensing properties of Pd-coated SnO2 nanorod (NR) arrays for detecting H-2 gas in N-2 and dissolved in transformer oil. The Pd nanoparticles were coated on randomly ordered vertical SnO2 NR arrays by the glancing angle deposition (GLAD) method, which utilizes an electron-beam evaporator and a DC magnetron sputtering system. The Pd-coated SnO2 NR arrays exhibited high response (104 at 1% H-2) in N-2. Pd-coated SnO2 NR arrays were immersed and in mineral oil that contains various concentrations of dissolved H-2 and the electrical response was measured. We found that the Pd-coated SnO2 NR arrays showed superior response (R = (similar to) 96), low detection limit (0.3 ppm), and fast response times (300 s). The Pd-coated SnO2 NR arrays had a temperature coefficient of resistance (TCR) of 3.69 x 10(-3) degrees C-1 at various oil temperatures (20-80 degrees C), indicating good thermal stability at high temperatures. The sensing mechanism of the Pd-coated SnO2 NR arrays was also demonstrated by using changes in the Schottky barrier height at the Pd/SnO2 interface upon exposure to H-2.