Abstract
For the rapid development of the hydrogen economy, a reliable and low-cost hydrogen sensor appears to be extremely important. Here, we first show that a palladium film deposited on polydimethylsiloxane (PDMS) can obtain an exceedingly high-reflectance contrast of 25.78 over the entire visible band upon exposure to 4 vol% hydrogen gas (H2) mixed with nitrogen gas. This high-reflectance contrast results from the surface deformation induced by the volume inflation after exposure to H2, leading to the transition of the near-specular surface to a diffusing surface. In addition, a change in brightness is readable by naked eye upon exposure to H2 with various concentrations from 0.6 to 1 vol% under the illumination of a fluorescent tube. Furthermore, this sensor possesses an excellent recyclability and quick response time of a few seconds. Compared with Pd nanostructure-based hydrogen sensors, this visual, high-contrast and low-cost sensor is of great potential for practical hydrogen sensing.
Highlights
Hydrogen is expected to substitute traditional fossil fuels as a sustainable and clean energy carrier in future energy systems
Assuming that the Pd film is fully hydrogenated, the reflectance would still exceed 38.0% based on the finite-difference time-domain (FDTD) simulation (Supplementary Fig. S1)
This outcome indicates that this abnormal reduction in reflectance conflicts with the existing sensing mechanism based on the change in the optical parameter of the Pd film after hydrogenation
Summary
Hydrogen is expected to substitute traditional fossil fuels as a sustainable and clean energy carrier in future energy systems. Palladium is widely used in hydrogen sensing owing to its reversible hydride formation and thermodynamic releasing hydrogen, Pd can form hydride phases in a reversible manner. This process is associated with a change in structural, electrical, and optical properties, providing the basis for designing Pd-based sensors. Conventional hydrogen detection is mainly based on electrical sensors, which have been demonstrated by Pd nanotubes[4], micro/nanowires[5,6,7,8], and thin films[9,10,11,12] with break junctions These sensors can generate electric sparks at the sensing point. Plasmonic hydrogen sensors have been developed because the surface plasmon resonance (SPR)
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