Towards one key to one lock: Catalyst modified indium oxide nanoparticle thin film sensor array for selective gas detection

Homogeneous In ₂O ₃ nanoparticles (NPs) were self-assembled into thin film sensor arrays on a single chip, with further surface modification by noble metal catalysts. The NP film sensor arrays show clear current responses when exposed to different target gases, and both sensitivity and selectivity were greatly improved. Particularly, the sensors modified with Au, Pd, and Pt nanocatalysts demonstrated higher sensitivity to H ₂S, H ₂ and CO, respectively, making the gas discrimination direct and simple, like "one key to one lock". The particle size dependence of the noble metal modifiers to the sensitivity was further investigated by tuning the sputtering parameters. Three different trends of sensitivities were observed, each attributed to different mechanisms. The modified nanoparticle film sensor was also fabricated on flexible substrates and the sensing performance was investigated at different bending angles.