Nickel nanoparticle-decorated reduced graphene oxide/WO₃ nanocomposite - a promising candidate for gas sensing

We report for the first time the combination of WO₃ sensing elements with a non-noble metal-carbon composite, namely a nickel metal nanoparticle-carbon composite (Ni@rGO). Previous work with WO₃ had used either NiO (as part of the WO₃ lattice), solely carbon, Pd-surface decorated WO₃ (Pd@WO₃), or Pd or Pt@carbon@WO₃. We demonstrate the gas response for pure WO₃, rGO/WO₃ and Ni@rGO/WO₃ sensing elements towards NO₂ and acetone in air as well as towards CO in N₂. The addition of 0.35 wt % Ni@rGO composite to WO₃ enables the increase of the sensory response by more than 1.6 times for NO₂ vapors. The gas response towards acetone using 0.35 wt % Ni@rGO/WO₃ composite was 1.5 times greater for 3500 ppm than for 35,000 ppm acetone. For 0.35 wt % Ni@rGO/WO₃ composite and CO gas, a response time (T _res) of 7 min and a recovery time (T _rec) of 2 min was determined.