Reconfigurable Flexible Plasmonic Hydrogen Sensor Based on Disordered Palladium Nanoparticles: Coupled Optical Modulation and 3D Structural Rearrangement

Hydrogen, a clean and renewable energy carrier, necessitates advanced sensing technologies for safe and efficient utilization. Here, we present a tunable flexible plasmonic sensor based on a disordered system composed of upper palladium (Pd) nanoparticles (NPs), a poly(methyl methacrylate) (PMMA) spacer, a lower Pd film, and a soft substrate. The contributions of Pd NPs and Pd films to the optical response at various hydrogen concentrations are different. The high sensitivity of the sensor at low concentration is achieved by the enhanced absorption of the Pd NPs due to the Fabry-Pérot (FP) like effect induced by the Pd NPs and Pd film. The remarkable optical contrast of 4540% at high concentrations is primarily attributed to the wrinkling of the Pd film due to volume expansion during hydrogenation. Furthermore, the sensor exhibits high hydrogen selectivity and a long lifetime, demonstrating great potential for hydrogen sensing applications. From a broad perspective, our work provides a novel hydrogen sensing strategy for next-generation optical gas sensors.