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 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.