Joong Ki Choi

Facile Control of C2H5OH Sensing Characteristics by Decorating Discrete Ag Nanoclusters on SnO2 Nanowire Networks

The effect of Ag decoration on the gas sensing characteristics of SnO(2) nanowire (NW) networks was investigated. The Ag layers with thicknesses of 5-50 nm were uniformly coated on the surface of SnO(2) NWs via e-beam evaporation, which were converted into isolated or continuous configurations of Ag islands by heat treatment at 450 °C for 2 h. The SnO(2) NWs decorated by isolated Ag nano-islands displayed a 3.7-fold enhancement in gas response to 100 ppm C(2)H(5)OH at 450 °C compared to pristine SnO(2) NWs. In contrast, as the Ag decoration layers became continuous, the response to C(2)H(5)OH decreased significantly. The enhancement and deterioration of the C(2)H(5)OH sensing characteristics by the introduction of the Ag decoration layer were strongly governed by the morphological configurations of the Ag catalysts on SnO(2) NWs and their sensitization mechanism.

ZnO-SnO 2 core-shell nanowire networks and their gas sensing characteristics

The ZnO nanowires (NWs) are grown by carbothermal reaction and SnO<inf>2</inf> shell layers are subsequently coated by vapor phase growth. The crystalline SnO<inf>2</inf> shell layer with the thickness of 5–20 nm was uniformly coated on the ZnO NWs with the diameter of 50–100 nm. The gas response of ZnO-SnO<inf>2</inf> core-shell NWs sensor to 10 ppm NO<inf>2</inf> at 200°C was increased up to ∼33 times compared to those of ZnO NWs. The enhancement of gas responses to NO<inf>2</inf> was discussed in relation to the thin SnO<inf>2</inf> shell layer and core-shell configuration of NWs.