Synergistic effects of (110) facet and oxygen vacancies on hydrangea - like SnO2 for ppb-level formaldehyde sensing

A unique hydrangea-like SnO2 assembled by ultrathin nanosheets interlaced with veins was successfully prepared via hydrothermal process. The sensor based on this material exhibits excellent sensing properties toward formaldehyde at 170 degree celsius, including a high response (8.5 to 1 ppm and 57.7 to 50 ppm), good selectivity, and quick response/recovery (7/16 s), with a detection limit of 3.9 to 80 ppb formaldehyde. These superior sensing characteristics can be attributed to the synergistic effect of the porous ultrathin nanosheets (similar to 12 nm) and the exposed (1 1 0) facets with more oxygen vacancies. The Density functional theory (DFT) calculations are applied to explore the formaldehyde sensing mechanism of the novel structure.