Substantially Accelerated Response and Recovery in Pd‐Decorated WO3 Nanorods Gasochromic Hydrogen Sensor

Abstract The development of hydrogen (H 2 ) gas sensors is essential for the safe and efficient adoption of H 2 gas as a clean, renewable energy source in the challenges against climate change, given its flammability and associated safety risks. Among various H 2 sensors, gasochromic sensors have attracted great interest due to their highly intuitive and low power operation, but slow kinetics, especially slow recovery rate limited its further practical application. This study introduces Pd‐decorated amorphous WO 3 nanorods (Pd‐WO 3 NRs) as an innovative gasochromic H 2 sensor, demonstrating rapid and highly reversible color changes for H 2 detection. In specific, the amorphous nanostructure exhibits notable porosity, enabling rapid detection and recovery by facilitating effective H 2 gas interaction and efficient diffusion of hydrogen ions (H + ) dissociated from the Pd nanoparticles (Pd NPs). The optimized Pd‐WO 3 NRs sensor achieves an impressive response time of 14 s and a recovery time of 1 s to 5% H 2 . The impressively fast recovery time of 1 s is observed under a wide range of H 2 concentrations (0.2–5%), making this study a fundamental solution to the challenged slow recovery of gasochromic H 2 sensors.