Palladium/Bismuth Nanowires with Rough Surface for Stable Hydrogen Sensing at Low Temperatures

Smart and reliable palladium (Pd)-based sensors that are able to operate in a large temperature range especially at low temperatures are highly desired but remain challenging because of the "reverse sensing behaviors" caused by the alpha-beta phase transition in PdHx. Heteroatom doping and morphology tuning are effective ways to improve the stability of Pd -based hydrogen sensors at low temperatures. Here, we have developed rough-surfaced palladium/bismuth nanowires (RS-PdBi NWs) with uniform diameters and even Bi atoms distribution via first AAO-confined electrodeposition and subsequent chemical etching. Remarkably, the hydrogen sensors built with RS-PdBi NWs are able to work in a larger temperature range of 194.3-400 K and much lower critical temperature (similar to 194.3 K) of "reverse sensing behavior" is achieved compared with the pristine Pd NWs sensors (similar to 287 K), exhibiting improved low-temperature stability. This superior sensing stability is attributed to the synergistic effect: Bi atom dopant modified the electronic structure of Pd atoms and the rough surface provided ample space for the PdHx expansion. The RS-PdBi NWs sensors with high stability have potential for reliable and rapid response toward hydrogen leakage in a wide low-temperature range (194.3-400 K).