Growth of SnO2/W18O49 nanowire hierarchical heterostructure and their application as chemical sensor

Hierarchical heterostructures consisting of W18O49 nanowires grown on SnO2 nanowires have been prepared by sequential thermal evaporation of tin and tungsten under partial oxygen atmosphere. Sensors made using isolated heterostructure nanowires showed superior selectivity for the detection of chlorine in comparison to isolated pure SnO2 nanowires as well as mat type films prepared using heterostructure nanowires. Improved response compared to mat type films arises due to different sensing mechanisms of chlorine arising from its adsorption or replacement of oxygen. On the other hand better selectivity in comparison to isolated SnO2 nanowires has been attributed to transfer of electrons across hetero-junction from W18O49 to SnO2 and lower sensitivity of W18O49 to H2S. The results show potential of tailored hierarchical nanoheterostructures for the fabrication of gas sensors.