Highly Stable and Ultrafast Hydrogen Gas Sensor Based on 15 nm Nanogaps Switching in a Palladium-Gold Nanoribbons Array

摘要

Palladium (Pd) nanogap hydrogen gas (H_2) sensors based on the large volume expansion of β phase palladium hydride (β-PdH) are highly promising, owing to their fast and accurate sensing capability at room temperature in air. However, such sensors do not work well at H_2 concentrations below 1%. At such low H_2 concentrations, Pd exists as α-PdH, which has a slow and insufficient volume expansion and cannot completely close nanogaps. Furthermore, the lattice strains induced from the phase transition (α-PdH → β-PdH) behavior degrade the stable and repeatable long-term sensing capability. Here, these issues are resolved by fabricating an array of periodically aligned alloyed palladium-gold nanoribbons (PdAu NRB) with uniform 15 nm nanogaps. The PdAu NRB sensor enables highly stable and ultrafast H_2 sensing at the full detection range of H_2 concentrations from 0.005% to 10% along with the excellent limit of detection (≈0.0027%), which is sufficiently maintained even after seven months of storage in ambient atmosphere. These breakthrough results will pave the way for developing a practical high-performance H_2 sensor chip in the future hydrogen era.