Ultra-sensitive hydrogen gas sensing properties of an InGaZnO4 thin film decorated with bimetallic nanoparticles

A new hydrogen (H2) gas sensor employing a synthesized InGaZnO4 (IGZO) thin film sandwiched within a bimetallic nanoparticle (NP) structure, consisting of bottom silver (Ag) NPs and top palladium (Pd) NPs, has been successfully fabricated and studied. Elemental analyses are conducted to evaluate the intrinsic properties. The synergistic effects of Ag NPs and Pd NPs effectively increase the surface roughness, specific surface area, and catalytic activity, leading to a significant improvement in H2 gas sensing performance. In experiments, the fabricated Pd NP/IGZO/Ag NP sensor achieves an ultrahigh sensing response SR of 1.44 × 106 as well as a response (recovery) time of 85 s (3 s) under 1% H2/air gas and an extremely low detectable level of 100 ppb H2/air at 275 °C. The studied sensor also exhibits excellent selectivity, repeatability, and long-term durability for up to 60 days during H2 gas sensing operation.