One-Dimensional Segregated Single Au Sites on Step-Rich ZnO Ladder for Ultrasensitive NO2 Sensors

Here, we develop a freestanding ladder-like ZnO surface with abundant unsaturated step defects, which could efficiently anchor Au1 sites with one-dimensional assembling for the ultrasensitive NO2 detection. The dimension of the obtained ZnO hexagonal ladder could be precisely controlled through reasonably regularizing the nucleation and growth rate. Following a layer-by-layer growth mode, the obtained ZnO would adopt the step-rich evolution. These ladder-like structures could provide abundant unsaturated step defects along with their curved edge profiles to serve as susceptible centers to site-selectively immobilize isolated Au1 species (Au1-ZnO). The obtained Au1-ZnO catalysts exhibit an outstanding NO2-sensing response (12.6 to 300 ppb) at a low operating temperature (150°C). The proposed step-induced strategy will broaden the rational design of special site-trapped supported metal catalysis for gas sensors.