Palladium and palladium oxide enwrapped iron oxide shell/core nanoparticles for stable detection of ppb-level hydrogen

[Display omitted] •Pd/PdO coated Fe2O3 shell/core nanoparticles (Pd/PdO@Fe2O3 NPs) are developed.•The H2 sensor detects as low as 300 ppb with 3 s fast response and high stability.•The sensing mechanism combines Pd/PdO “spillover effect” and PdO/Fe2O3 junction.•Simulating detection of hydrogen presents the fast and reliable response. Hydrogen (H2) sensing simultaneously endowed with ppb-level detection limit, fast response and high stability is highly desired in future exhaled diagnosis of small intestinal bacterial overgrowth, however, it is still less than satisfactory. Here, a stable and ppb-level H2 sensing has been developed with palladium and palladium oxide coated iron oxide shell/core nanoparticles (Pd/PdO@Fe2O3 NPs), which have been prepared by [Fe(CN)6]3− of Pd-Fe cyanogel governed self-assembly, reduction and “dipolar interaction”. Typically, the obtained Pd/PdO@Fe2O3 NPs around 100 nm in diameter are observed with “sugar snowball” shell/core shapes. Beneficially, the Pd/PdO@Fe2O3 NPs present a low detection limit of 300 ppb, a fast response time of 3 s toward 500 ppm H2 and an excellent selectivity at 200 °C. Further, the Pd/PdO@Fe2O3 NPs show outstanding humidity-tolerant and long-term stability. Such excellent H2 sensing performance might be attributed to the Pd/PdO “spillover effect” promoting the electron transfer, and more adsorbed oxygen modulating charge accumulation via forming PdO/Fe2O3 p-n heterojunctions. Practically, a sensor prototype built with Pd/PdO@Fe2O3 NPs has been integrated to simulate the real-time detection of H2 with a reliable response.