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.