Visual hydrogenation of palladium membranes on an elastic substrate and their applications in hydrogen sensing

Abstract

Abstract The study of metal‐hydrogen interaction is essential for hydrogen‐related applications. Due to the small permittivity variation of palladium (Pd), it is difficult to visualize its hydrogenation processes. Soft substrates can release the expansion stress of Pd membrane and form wrinkling during hydrogenation, which can be utilized to track the hydrogen diffusion. Here, we investigate the hydrogenation processes of Pd membranes with various shapes and sizes on polydimethylsiloxane (PDMS) substrates. It was found that the Pd membranes priorly wrinkles from the edges during hydrogenation and the saturation time of hydrogen absorption reduces with the decreasing size of Pd membranes. With these measurements, we fabricate a high‐performance optical hydrogen sensor consisted of a Pd nanostripe array on PDMS. Due to the transition from specular reflection to scattering during the surface wrinkling of the Pd nanostripe, when exposed to 4% hydrogen gas mixed with nitrogen gas, the sensor shows a high‐reflectance contrast of more than 800% with the absolute reflectance change exceeding 32% over the visible band, and the response time t90 is about 1.5 seconds. These results suggest that the Pd membranes on an elastic substrate is a promising platform for visualization of hydrogen diffusion and hydrogen detection.

Keywords

• elastic substrate
• hydrogen sensor
• palladium membrane
• surface wrinkling
• visual hydrogenation