Ultra-large Sn3O4 nanosheets with Sn2+defect for highly efficient hydrogen sensing

Hydrogen (H2) is the cleanest energy but also dangerous, thus the real-time detection of H2 leakage is crucially important. Herein, we develop ultra-large micro-sized Sn3O4 nanosheet hierarchies via a facile hydrothermal method using polyvinyl pyrrolidone as a regulating agent. Structural analyses reveal the as-prepared Sn3O4 nanosheets are single-crystalline with {010}-facet exposure and Sn2+-deficiency. When examined as gas sensing materials, the {010}-faceted Sn2+-deficient Sn3O4 nanosheets demonstrate highly efficient H2 sensing with excellent selectivity/response (two times higher than those for NO2, SO2, H2S, and H2O) and stability upon long-term testing (over 37 days). The sensor displays fast response /recovery times of 9.4/24 s to 10 ppm H2 at a low working temperature of 150 degrees C, and even well responds to 50 ppb H2 with a theoretical limit of detection (LOD) of 0.54 ppb. The excellent H2 sensing performance of the Sn3O4 nanosheets has been verified by the first-principle calculation based on density functional theory (DFT), suggesting that the Sn2+-deficient {010} sur-face of Sn3O4 provides abundant adsorption sites for hydrogen molecules. Moreover, we demonstrate the practical application of Sn3O4 sensor embedded into a miniaturized deployable module, which realizes the real -time on-line H2 monitoring with excellent repeatability and selectivity for long-term operation.