Surface-broken palladium and palladium oxide core/shell nanowires for stable hydrogen sensing at room temperature

Hydrogen (H2) sensing materials with desired geometrical shapes would contribute to stable hydrogen sensing at room temperature, however, their controllable synthetic strategy needs further exploring. Herein, a surface -broken nanowire with palladium (Pd) as the core and PdO as the shell (PdO@Pd NWs) has been developed for stable hydrogen sensing, which has been synthesized via combined anode-aluminum-oxide template-confined electrodeposition, annealing and wet-chemical etching. Specifically, PdO@Pd NWs arrays with a diameter of-50 nm are observed, in which surface-broken PdO shells are in situ formed around Pd NWs. Beneficially, the PdO@Pd NWs show excellent cycling stability to 1 v/v% and 0.5 v/v% H2 at room temperature (-25 degrees C) and a relative humidity of-75%, respectively. Further, a sensing response is as fast as 5 s (1 v/v% H2 at-25 degrees C) and a detection limit is as low as 10 ppm. Theoretically, the outstanding stability and sensing response might be attributed to the synergic effect, in which Pd cores absorb and desorb H2 through broken PdO shells, and Pd/PdO constructed "spillover effect" and PdH chi intermediates may contribute to improving sensing stability, fast response and ppm detection limit. Practically, a hydrogen sensing device integrated with PdO@Pd NWs is built to detect hydrogen leakage.