Abstract
Indium oxide (In2O3) nanomaterials have been investigated extensively as promising candidates for gas sensor applications. Here, we fabricate near room temperature operable H2S-sensitive gas sensors based on In2O3 colloidal quantum dots (CQDs). Room-temperature film deposition of In2O3 CQDs followed by surface ligand exchange treatment through Cu inorganic salts was employed to construct the sensor devices. Combined with a moderate annealing treatment, the long-chain ligands surrounding the quantum dot surfaces were completely removed to enhance gas adsorption and carrier transport, simultaneously resulting in the formation of CuO that may act as a catalytic promoter or form p-n heterojunction for selective H2S detection. The sensors exhibited high response up to 90 toward 5 ppm of H2S with response/recovery time of 72 s/200 s respectively, suggestive of a performance improvement compared to the In2O3-based H2S sensors reported in existing literature.The power law analysis indicated that the main oxygen species adsorbed on the surfaces were O2− and O− with the proportion of approximate 1:1 at near room temperature. The gas-sensing mechanism was attributed to the decisive role of surface states in determining the electrical conduction of quantum dot gas sensors.
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