Pd₈₀Co₂₀ Nanohole Arrays Coated with Poly(methyl methacrylate) for High-Speed Hydrogen Sensing with a Part-per-Billion Detection Limit

As hydrogen gas increasingly becomes critical as a carbon-free energy carrier, the demand for robust hydrogen sensors for leak detection and concentration monitor will continue to rise. However, to date, there are no lightweight sensors capable of meeting the required performance metrics for the safe handling of hydrogen. Here, we report an electrical hydrogen gas sensor platform based on a resistance nanonetwork derived from Pd-Co composite hole arrays (CHAs) on a glass substrate, which meets or exceeds these metrics. In optimal nanofabrication conditions, a single poly­(methyl methacrylate)­(PMMA)-coated CHA nanosensor exhibits a response time (t₈₀) of 1.0 s at the lower flammability limit of H₂ (40 mbar), incredible sensor accuracy (<1% across 5 decades of H₂ pressure), and an extremely low limit of detection (LOD) of <10 ppb at room temperature. Remarkably, these nanosensors are extremely inert against CO and O₂ gas interference and display robust long-term stability in air, suffering no loss of performance over 2 months. Additionally, we demonstrate that the unique nanomorphology renders the sensors insensitive to operation voltage/current with diminutive power requirement (∼2 nW) and applied magnetic field (up to 3 kOe), a crucial metric for leak detection and concentration control.