Spontaneous growth of ZnCO₃ nanowires on ZnO nanostructures in normal ambient environment: Unstable ZnO nanostructures

ZnO nanowires, one of the most investigated nanostructures that promise numerous applications in nanophotonics, opto-electronics, and energy, are generally thought to be highly stable under ambient conditions because of their oxide nature. Here, we report that ZnO nanowires are actually extremely unstable even in normal ambient environment (70% RH, and ∼350 ppm CO₂) because of atmospheric corrosion. When placed on an oxide substrate (e.g., glass slide) and exposed in air, ZnO nanowires tend to react with airborne moisture and CO₂ to form amorphous ZnCO₃ thin films and nanowires. The factors that specially affect the corrosion of ZnO nanowires in a laboratory environment include CO₂, humidity, and substrates. Our results suggest that a CO₂- and/or moisture-free environment are required in order for optimal applications of ZnO nanowires.