Parts per Billion-Level H 2 S Detection at Room Temperature Based on Self-Assembled In 2 O 3 Nanoparticles

Homogenous In 2 O 3 nanoparticles (NPs) with diameters in the range of 6−10 nm were synthesized via a chemical solution method, and nanoparticles were assembled on Si substrate for H 2 S detection. The sensor demonstrates ultrahigh sensitivity to H 2 S to part per billion (ppb) levels at room temperature. Different sensor parameters were then investigated in terms of electrode gap, In 2 O 3 NP film thickness, and surface modification by noble metals. It was found that sensitivity was slightly improved by reducing the electrode gap or increasing NP film thickness. However, sensitivity was dramatically enhanced (from 20 ppm to 20 ppb) after surface modification with 0.3 nm Au deposition. In addition, the sensor also shows a certain selective detection to H 2 S in comparison with other gases such as CO and NO 2 .