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 α–β 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 (∼194.3 K) of “reverse sensing behavior” is achieved compared with the pristine Pd NWs sensors (∼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).