Synergistically Boosting the Surface Reaction Dynamics by K+ Interstitial Doping in Pd/WO3 Nanosheets for Robust Hydrogen Sensing

The development of highly sensitive and reliable hydrogen detection technology is a critical prerequisite for the safe and large-scale application of green hydrogen energy. Pd-based metal oxide semiconductor sensors exhibit decent sensing performance; however, their development for hydrogen detection is hindered by competitive adsorption of hydrogen and oxygen on the surface and sluggish reaction kinetics due to limited active interfaces. Here, a series of Pd nanoparticle-decorated, K+ interstitial doping WO3 nanosheets (PdNP-K/WO3-x) were synthesized. The optimized PdNP-K/WO3-15 sample exhibited exceptional H2 sensing performance, including a high response (Ra/Rg = 1235.94 to 50 ppm H2) at a low temperature of 130 °C, with fast response/recovery. This enhancement stems from synergistic effects where K+ interstitial doping increases electron density and oxygen vacancies in WO3, improving charge transfer and strengthening the W-O-Pd interface. The resulting electron-rich environment also shifts the d-band center of Pd, enhancing hydrogen desorption and spillover, while reducing competitive oxygen adsorption to free up more Pd active sites. The material also showed promising room-temperature sensing, indicating strong application potential and providing a theoretical basis for designing high-performance alkali metal ion-doped metal oxide materials.