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.