Hydrogen Gas Sensors Using Palladium Nanogaps on an Elastomeric Substrate

With the recent reillumination of the hydrogen economy around the world, the demand for H₂ sensors is expected to increase rapidly. Due to safety issues caused by the highly flammable and explosive character of hydrogen gas (H₂), it is imperative to develop the sensors that can quickly and sensitively detect H₂ leaks. For the development of H₂ sensors, Pd-based materials have been extensively used due to the high affinity of Pd metal for H₂. Among Pd-based H₂ sensors, Pd nanogap-based sensors have been extensively investigated because these sensors can operate in an on–off manner, which enables them to have improved sensing capabilities, including high sensitivity, rapid response, short recovery time, and good reliability. Importantly, significant advances in H₂-sensing performance have been achieved by simply using an elastomeric substrate to form Pd nanogaps. Herein, the progress and advanced approaches achieved over the last decade for Pd nanogap-based H₂ sensors supported on elastomeric substrates are reviewed, with a focus on strategies to reduce detection limits and increase reliability, sensitivity, and stability.