Pd Nanoparticle Film on a Polymer Substrate for Transparent and Flexible Hydrogen Sensors

Alongside the rise in fully automated equipment and wearable devices, there is currently a high demand for optically transparent and flexible gas sensors operating at room temperature. Nanoparticle films are ideal H₂-sensing materials that can be coupled with flexible substrates because of their discrete nanogranular structure and unique interparticle electrical responsiveness. In this work, we present an optically transparent and flexible H₂ sensor based on a Pd nanoparticle film, prepared on a polyethylene terephthalate sheet using a straightforward nanocluster deposition technique. Hundreds of bending cycles demonstrated that the sensor has good electrical stability and mechanical robustness without significant degradation in H₂-sensing performance. The H₂-sensing behaviors under bent state were systematically evaluated. The loading of tensile and compressive strains under bent state produced a positive and negative influence, respectively, on the sensing performances. The possible influence mechanism of the tensile and compressive strains on the H₂-sensing performance was attributed to the changes in the percolation network topology and the interparticle space induced by the strains. The ability to detect a H₂ concentration as low as 15 ppm, dynamic response range as wide as 0-10%, and sub-10 s response time was achieved. In addition, the sensor can be operated in the relative humidity range of 0-90% at room temperature. These results demonstrate that the sensor exhibits significant potential for next-generation transparent and flexible H₂ detectors.