A Highly Sensitive ppb-Level H2 Gas Sensor Based on Pt/PtO and Pd/PdOx Co-Decorated WO3 Nanofibers Prepared by Electrospinning

A highly sensitive ppb-level resistive H2 gas sensor was fabricated based on Pt/PtO and Pd/PdOx co-decorated WO3 nanofibers prepared via electrospinning and calcination. The optimized sensor based on 2 at% Pt–2 at% Pd co-decorated WO3 nanofibers exhibited reliable detection toward 100 ppb H2 at an optimized operating temperature of 170 °C. Upon 2 at% Pd decoration, the response of the WO3-based sensor increased from 1, corresponding to almost no response, to 55 (Ra/Rg) toward 100 ppm H2. Further introduction of 2 at% Pt reduced the optimal operating temperature of the 2 at% Pd-decorated WO3-based sensor from 200 °C to 170 °C and enhanced the response by approximately twofold. The optimal sensor exhibits excellent linear response characteristics, high selectivity, good response repeatability, and long-term operational stability. The enhanced sensing performance is attributed to the catalytic capability and possible spillover-related effects of Pd/PdOx and Pt/PtO toward H2/O2, as well as depletion-layer modulation induced by the heterostructures between Pt/PtO and WO3, and Pd/PdOx and WO3. These synergistic catalytic and electronic sensitization effects collectively contribute to the high sensitivity toward H2. These results indicate that the proposed resistive H2 sensor holds significant potential for practical hydrogen-sensing applications.