Decorating Pd-Au Nanodots Around Porous InO Nanocubes for Tolerant H Sensing Against Switching Response and HS Poisoning.

With the recently-booming hydrogen (H) economy by green H as the energy carriers and the newly-emerged exhaled diagnosis by human organ-metabolized H as a biomarker, H sensing is simultaneously required with fast response, low detection limit, and tolerant stability against humidity, switching, and poisoning. Here, reliable H sensing has been developed by utilizing indium oxide nanocubes decorated with palladium and gold nanodots (Pd-Au NDs/InO NCBs), which have been synthesized by combined hydrothermal reaction, annealing, and chemical bath deposition. As-prepared Pd-Au NDs/InO NCBs are observed with surface-enriched NDs and nanopores. Beneficially, Pd-Au NDs/InO NCBs show 300 ppb-low detection limit, 5 s-fast response to 500 ppm H, 75%RH-high humidity tolerance, and 56 days-long stability at 280 °C. Further, Pd-Au NDs/InO NCBs show excellent stability against switching sensing response, and are tolerant to HS poisoning even being exposed to 10 ppm HS at 280 °C. Such excellent H sensing may be attributed to the synergistic effect of the boosted Pd-Au NDs' spillover effect and interfacial electron transfer, increased adsorption sites over the porous NCBs' surface, and utilized Pd NDs' affinity with H and HS. Practically, Pd-Au NDs/InO NCBs are integrated into the H sensing device, which can reliably communicate with a smartphone.