Nano-Schottky-junction-engineered Pd/SnO nanotube array for ultrasensitive hydrogen sensing at room temperature.

Detecting H at low concentrations is important due to it being a major safety concern in practical applications. However, semiconductor chemiresistive gas sensors always suffer from high operating temperatures and power consumption, as well as a limited concentration detection range, which restricts their widespread use. Herein, we developed a 3D nanostructured gas sensor employing a Pd-nanocluster-decorated SnO nanotube array as the sensing layer. The sensor showed sensitive and selective properties for detecting low concentrations of H at room temperature, with a low limit of detection of 1.6 ppb. It also showed good long-term stability, as long as 100 days. Moreover, systematical characterizations were performed in conjunction with density functional theory (DFT) calculations to determine the ability of Pd/SnO junctions to improve the gas-sensing properties. The engineering of the nano-Schottky junction allows us to expand the library for designing low-power-consumption H sensors for widespread applications.