Two-dimensional Aluminum Oxide Nanosheets Decorated with Palladium Oxide Nanodots for Highly Stable and Selective Hydrogen Sensing.

Hydrogen (H 2 ) sensing materials such as semiconductor metal oxides may suffer from poor long-term stability against humidity and unsatisfactory selectivity against other interfering gases. To address the above issues, highly stable and selective H 2 sensing built with palladium oxide nanodots decorating aluminum oxide nanosheets (PdO NDs//Al 2 O 3 NSs) has been achieved via combined template synthesis, photochemical deposition, and oxidation. Typically, the PdO NDs//Al 2 O 3 NSs are observed with thin NSs (≈17 nm thick) decorated with nanodots (≈3.3 nm in diameter). Beneficially, the sensor prototypes built with PdO NDs//Al 2 O 3 NSs show excellent long-term stability for 278 days, high selectivity against interfering gases, and outstanding stability against humidity at 300 °C. Remarkably, the sensor prototypes enable detection of a wide-range of 20 ppm - 6 V/V% H 2 , and the response and recovery times are ≈5 and 16 s to 1 V/V% H 2 , respectively. Theoretically, the heterojunctions of PdO NDs-Al 2 O 3 NSs with a large specific surface ratio and Al 2 O 3 NSs as the support exhibit excellent stability and selective H 2 sensing. Practically, a sensing device integrated with the PdO NDs//Al 2 O 3 NSs sensor prototype is simulated for detecting H 2 with reliable sensing response.