Improved H2-sensing performance of nanocluster-based highly porous tungsten oxide films operating at moderate temperature

Many nano-metal oxides are claimed to be responsive to H2 at room-temperature, but their response rates may be too low for the signal to reach equilibrium quickly. We investigated the H2-induced resistive response of palladium-coated supersonic cluster beam deposited tungsten oxide (Pd/SCBD WO3) films at temperatures Tsen between 20 and 140°C. They are constructed of genuine nano WO3 clusters (3–5nm) loosely packed together, and have a high porosity. Slight increase of Tsen from room-temperature greatly speeds up the response rate and gives a strong apparent sensor response. Other advantages include excellent cyclic stability and selectivity against vapors of various organic compounds; negligible influence from moisture and mild ambient pressure dependence.