Selective trimethylamine sensors using Cr2O3-decorated SnO2 nanowires

Pristine SnO2 nanowires (NWs), Cr2O3-decorated SnO2 NWs, and SnO2–Cr2O3 core-shell nanocables (NCs) were prepared by thermal evaporation, and their gas-sensing characteristics were investigated. The decoration of discrete p-type Cr2O3 nanoclusters on SnO2 NWs increased their response to trimethylamine (TMA). Highly sensitive and selective detection of TMA was attributed to the chemical affinity and catalytic activity of Cr2O3 toward TMA. In contrast, the SnO2–Cr2O3 NCs, formed by the coating of a continuous p-type Cr2O3 overlayer on SnO2 NWs, showed negligibly low responses to all analyte gases used. The variations in gas-sensing characteristics due to configuration changes in one-dimensional SnO2–Cr2O3 hetero-nanostructures are explained and discussed in relation to the gas-sensing mechanisms of n- and p-type oxide semiconductors.