Self-Cleaning Pd–TiO2–WO3 Heterostructure for High-Performance Hydrogen Gas Sensing

WO3-based gasochromic hydrogen sensors are highly attractive for visual hydrogen-leak detection because they operate without an external power supply and provide an intuitive optical readout. However, their practical application remains limited by catalyst poisoning and insufficient readability at low hydrogen concentrations. In this work, a self-cleaning Pd-TiO2-WO3 heterostructure was constructed via a facile hydrothermal method combined with Pd deposition, in which TiO2 was in situ grown on three-dimensional WO3 nanoflowers to simultaneously enhance optical readability toward low-concentration hydrogen and introduce photocatalytic self-cleaning capability against catalyst poisoning. Gasochromic tests showed that the sample with a WO3/TiO2 mass ratio of 1:1 exhibited the best hydrogen-sensing performance. At room temperature, it showed a response time of 23.9 s and a color difference (ΔE) of 7.3 toward 0.1% H2, while toward 4% H2, the response time decreased to 11.5 s and ΔE increased to 15.8. RhB photodegradation and CO poisoning/recovery experiments further confirmed its efficient photocatalytic decontamination capability and improved resistance to catalyst poisoning. Density functional theory calculations revealed enhanced hydrogen adsorption and charge transport in the Pd-TiO2-WO3 system, consistent with the improved response kinetics and antipoisoning durability. This work provides a practical strategy for developing high-performance, antipoisoning gasochromic hydrogen sensors for complex industrial environments.