Optimization of Al2O3 shell thickness on SnO2 nanowires for realization of sensitive and selective H2 sensing

Abstract

Detection of highly explosive H2 gas is a critical safety issue. Herein, using a vapor-liquid-solid growth mechanism, SnO2 nanowires (NWs) were prepared, after which Al2O3 shells (1.9, 3.3, 4.5, and 6.1 nm) were deposited on synthesized SnO2 NWs by atomic layer deposition. Based on characterization studies, C-S NW structures with a crystalline SnO2 core and amorphous Al2O3 shell were successfully formed. Based on H2 gas sensing measurement, SnO2-Al2O3 (4.5 nm) C-S NWs exhibited a high response of 152.54 to H2 (10 ppm) at 350°C. Furthermore, they showed excellent selectivity, where response to H2 gas (10 ppm) was more than 33 times higher than that to NO2 gas (10 ppm). Additionally, they displayed excellent repeatability as well as long-term stability in detection of low-concentration H2 gas. The improved H2 sensing capability was related to the high base resistance, the formation of the SnO2-Al2O3 heterojunction, the optimization of the Al2O3 shell thickness on SnO2 NWs, and the partial reduction of SnO2 and Al2O3 in an H2 gas atmosphere. This study sheds light on the development of H2 sensors based on present material.