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

The development of hydrogen (H₂) gas sensors is essential for the safe and efficient adoption of H₂ gas as a clean, renewable energy source in the challenges against climate change, given its flammability and associated safety risks. Among various H₂ 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 WO₃ nanorods (Pd-WO₃ NRs) as an innovative gasochromic H₂ sensor, demonstrating rapid and highly reversible color changes for H₂ detection. In specific, the amorphous nanostructure exhibits notable porosity, enabling rapid detection and recovery by facilitating effective H₂ gas interaction and efficient diffusion of hydrogen ions (H⁺) dissociated from the Pd nanoparticles (Pd NPs). The optimized Pd-WO₃ NRs sensor achieves an impressive response time of 14 s and a recovery time of 1 s to 5% H₂. The impressively fast recovery time of 1 s is observed under a wide range of H₂ concentrations (0.2-5%), making this study a fundamental solution to the challenged slow recovery of gasochromic H₂ sensors.