Ag-induced interfacial electronic regulation of hierarchical In2O3 microflowers for room-temperature H2S sensing

Hydrogen sulfide (H 2 S) is a highly toxic, corrosive, and flammable gas. Therefore, rapid and low-power monitoring under room-temperature conditions is of great importance. However, room-temperature chemiresistive metal-oxide sensors generally suffer from weak H 2 S adsorption and sluggish surface reaction kinetics, resulting in insufficient electrical signals. To address this issue, we developed hierarchical Ag/In 2 O 3 microflowers based on coupled interfacial electronic regulation and reaction activation. The optimized Ag/In 2 O 3 -3 sensor exhibited a response of 11176 toward 10 ppm H 2 S at 25°C, approximately 28.7 times that of pristine In 2 O 3 , together with a response time of 6 s and the lowest tested concentration of 2 ppb. The sensor also maintained a preferential response toward H 2 S, reproducible cycling, detectable operation over 38-84% RH, and stable performance over 35 days. BET measurements revealed only a minor change in specific surface area after Ag modification. XPS and UPS indicated changes in the surface electronic environment, whereas post-exposure XPS and SO 2 detection supported the participation of Ag-containing sites and surface oxygen species in H 2 S oxidation. DFT calculations further show that Ag modification strengthens H 2 S adsorption from −0.56 to −0.93 eV and enhances adsorption-induced charge redistribution. These results demonstrate that coupling interfacial electronic regulation with reaction activation provides an effective route for highly sensitive H 2 S sensing at room temperature.