Atomic step formation on porous ZnO nanobelts: remarkable promotion of acetone gas detection up to the parts per trillion level

Abstract

Atomic defects, such as steps and kinks, can promote the efficiency of chemical reactions. These defects provide coordinatively unsaturated sites (CUSs) in metal oxides and the CUSs react with other molecules with relatively lower energy. Thus, decoration with atomic step structures can be a cost-effective strategy that can replace novel metal catalysts to enhance the gas sensing performance. Herein, atomic step structure decorated porous ZnO nanobelts were synthesized for acetone gas sensing below the parts-per-trillion (ppt, 10⁻¹²) level. Numerous atomic step structures could be formed by removing H and F atoms that occupied a high atomic ratio and a low weight ratio, during the conversion process of ZnOHF. Atomic step structures on ZnO allow an outstanding sensitivity, i.e., detection up to 200 ppt, and its theoretical limit of detection (LOD) was 72 ppt. This result was due to the edge of the atomic step that promotes electron transfer and induces oxygen chemisorption by restricting the diffusion on the flat surface. The atomic defect engineering on the metal oxide by conversion from metal hydroxide fluoride will trigger the fabrication of extremely sensitive sensing materials that do not require novel metal catalysts.