Fabrication of comb-like ZnO nanostructures for room-temperature CO gas sensing application

Comb-like ZnO nanostructures are prepared by chemical vapor deposition in a quartz vial and characterized by a scanning electron microscope. The comb-like ZnO structures are several tens of micrometers. The lengths of the branches (nanowires) gradually decrease along the growth direction of the comb-like ZnO structures. The branches have uniform diameters and are evenly distributed on the belt-stem. Electrical measurements indicate that the comb-like ZnO is intrinsic n-type semiconductor. Moreover, the nanostructures have good sensing properties. It is found that an individual ZnO comb exhibits fast and large response to ppm-level CO gas even at room temperature. The sensing mechanism is also discussed briefly. These results demonstrate that comb-like ZnO nanostructures have potential application in gas sensors without an external heater.