A flexible hydrogen sensor based on Pd nanoparticles decorated ZnO nanorods grown on polyimide tape

This paper describes the fabrication and characterization of flexible hydrogen sensors using ZnO nanorods (NRs) incorporated with a Pd catalyst for hydrogen detection at room temperature. The well-aligned, vertical ZnO NRs are grown on a polyimide tape substrate, and are successfully synthesized using an aqueous solution method. Pd nanoparticles approximately 10 nm in size were used as catalysts, and were deposited into a ZnO NR array network with RF magnetron sputtering. The resulting flexible hydrogen sensors showed a high performance with fast response, and excellent mechanical flexibility. Response factors of ∼91% with good repeatability and stability were achieved for 1000 ppm hydrogen at room temperature, 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 nanoparticle-decorated ZnO NRs can be a promising building block for flexible hydrogen sensors, combining a fast response with stable performance.