Fullerene-Decorated PdCo Nano-Resistor Network Hydrogen Sensors: Sub-Second Response and Part-per-Trillion Detection at Room Temperature

We present a novel hydrogen (H ₂ ) sensor based on a hexagonal PdCo composite nano-resistance network, featuring an innovative layered nanostructure and advanced materials. This state-of-the-art PdCo network is deposited on a thin layer of nanoporous fullerene C ₆₀ -coated glass substrate using a combination of nanosphere lithography and the glancing angle codeposition (GLACD) technique, which significantly enhances the quality, morphology, and surface-to-volume ratio of the PdCo sensing elements to their full potential. Remarkably, this approach not only simultaneously improves the sensor's response time and sensitivity but also effectively mitigates the clamping effect. Our results demonstrate that the sensor, composed of a 20 nm C ₆₀ /5 nm Pd ₆₃ Co ₃₇ /30 nm Teflon AF composite hole array, achieves a response time (t ₉₀ ) of ≤ 0.8 seconds across the 1 – 100 mbar H ₂ pressure range, with a limit of detection (LOD) of 40 parts per billion (ppb). Remarkably, when the Pd ₆₃ Co ₃₇ sensing layer is sandwiched by two TAF layers, the t ₉₀ and LOD reach 0.36 s at 1 mbar H ₂ and ~100 parts per trillion (ppt) H ₂ , respectively. Additionally, when coated with an additional layer of Poly(methyl methacrylate) (PMMA), the sensor maintains robustness over hundreds of hydrogen cycling and aging effects and remains resilient against interference from gases such as CO ₂ , CH ₄ , and CO, as well as up to 90% relative humidity (RH). This low-cost, lightweight, and low-power hydrogen sensor platform holds significant potential to meet the stringent sensing requirements for automotive applications, concentration control, and environmental monitoring.