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

Abstract

We report enhanced sensing properties of Pd-coated SnO2 nanorod (NR) arrays for detecting H2 gas in N2 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% H2) in N2. Pd-coated SnO2 NR arrays were immersed and in mineral oil that contains various concentrations of dissolved H2 and the electrical response was measured. We found that the Pd-coated SnO2 NR arrays showed superior response (R = ˜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 × 10-3 °C−1 at various oil temperatures (20–80 °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 H2.