Highly Sensitive Room‐Temperature Hydrogen Detection with Palladium Nanoparticle‐Based Capacitive‐Type Sensors

Abstract Palladium nanoparticle (Pd NP)‐based resistive‐type hydrogen (H 2 ) sensors are susceptible to interference from oxygen when detecting H 2 . In contrast, capacitive‐type sensors emerge as promising candidates for addressing this issue, owing to their unique operating principle. Herein, a capacitive‐type H 2 sensor is developed to verify the conception, using Pd NPs as the sensing material and integrating them into a novel 3D interdigital electrode (IDE) structure fabricated on a silicon wafer via microelectromechanical systems (MEMS) technology. Comprehensive characterization of the Pd NPs within the 3D IDEs reveals a strong correlation between sensitivity and Pd NP content, with peak sensitivity (61.94) attained at 20 000 ppm H 2 for ≈0.7 mg of Pd NPs. The sensor demonstrated negligible interference from CH 4 , CO 2 , and CO, underscoring its exceptional selectivity for H 2 . Particularly, variation of oxygen concentration in the background gas shows a minor impact on the sensing performance of the developed capacitive H 2 sensor. Additionally, density functional theory (DFT) calculations provide insight into the volumetric expansion of Pd at different H/Pd ratios, showing a maximum expansion of 13.7% at an H/Pd ratio of 1. This work highlights the potential of capacitive‐type sensors for high‐performance tracking H 2 , paving the way for advanced applications in H 2 monitoring.