High performance flexible hydrogen sensor based on Pd-coated ZnO nanorods on polyimide tape

In this study, the fabrication and characterization of flexible hydrogen sensors using ZnO nanorods (NRs) incorporated with a Pd catalyst for hydrogen detection at room temperature are demonstrated. The well-aligned, vertical ZnO NRs are grown on a polyimide tape substrate using an aqueous solution method. Pd nanoparticles (NPs), around 10 nm in size were used as catalysts, deposited by RF magnetron sputtering. Sensors showed high sensitivity with fast response, and excellent mechanical flexibility. Response factors of ~91% with good repeatability and stability were achieved for 1000 ppm hydrogen and the sensor limit of detection (LOD) was 0.2 ppm. Sensor performance did not significantly degrade, even when bent at a curvature angle of 90°, and through 10⁵ cycles to an angle of 90°. Light weight, mechanically robust Pd NPs-decorated ZnO NRs can be a promising building block for flexible hydrogen sensors.