Extremely sensitive and selective sub-ppm CO detection by the synergistic effect of Au nanoparticles and core-shell nanowires

An extremely sensitive CO sensor based on novel hybrid SnO2-ZnO core-shell (C-S) nanowires (NWs) functionalized by Au nanoparticles (NPs) was synthesized. First, networked SnO2 NWs were successfully prepared using the vapor-liquid-solid growth method on an electrode layer with special patterns. A ZnO shell was subsequently coated on the SnO2 core using atomic layer deposition, and Au NPs were then attached onto the ZnO shell using γ-ray radiolysis. The resulting sensor exhibited a very high response of 26.6-100 ppb CO gas. Furthermore, the responses to other gases such as C6H6 and C6H7 were extremely low, indicating the very good selectivity of the sensor to CO gas. Besides acting as heterojunctions, the catalytic effect of the Au NPs on CO gas greatly improved the CO sensing capability of the Au-functionalized SnO2-ZnO C-S NWs. The high sensitivity and selectivity of this sensor can open a path for prompt toxic monitoring and early detection of fatal diseases related to CO.