Catalyst-free Highly Sensitive SnO Nanosheet Gas Sensors for Parts per Billion-Level Detection of Acetone.

The development of a facile gas sensor for the ppb-level detection of acetone is required for realizing health diagnosis systems that utilize human breath. Controlling the crystal facet of a nanomaterial is an effective strategy to fabricate a high-response gas sensor without a novel metal catalyst. Herein, we successfully synthesized a SnO nanosheet structure, with mainly exposed (101) crystal facets, using a SnF aqueous solution at 90 °C. The SnO nanosheets obtained after various synthesis durations (2, 6, and 24 h) were investigated. The sample synthesized for 6 h (NS-6) exhibited a 10-fold higher response (/ = 10.4) for 1 ppm of acetone compared to the other samples, where and are the electrical resistances under air and the target gas. Furthermore, NS-6 detected up to 200 ppb of acetone (response = 3). In this study, we attributed the high response (of low concentrations of acetone) to the (101) crystal facet, which is the main reaction surface. The (101) crystal facet allows the facile formation of a depletion layer due to the highly reactive Sn. Additionally, the acetone adsorption energy of the (101) crystal facet is relatively lower than that of other crystal facets. Owing to these factors, our pristine SnO nanosheet gas sensor exhibited significantly high sensitivity to ppb levels of acetone.