Palladium and gold nanotube arrays with tuned surfaces for low-temperature hydrogen sensing

Abstract

Palladium (Pd) and its alloys are highly desired for stable hydrogen (H₂) sensing at low temperatures (<273 K) in harsh environments, which need further improvement. Herein, Pd and gold (Au) nanotube arrays (PdAu NTs) with tuned surfaces are developed for low-temperature H₂ sensing. By combined anodic aluminum oxide (AAO) template-confined electrodeposition and wet-chemical etching, the dopant gold (Au) facilitates the formation of PdAu NTs with various shapes and a wall thickness of ∼10–23 nm. Typically, the as-prepared PdAu NTs take on shapes including broken NTs, smooth NTs, and NTs with incomplete walls. Remarkably, PdAu NTs with rough and broken surfaces (RB-PdAu NTs) exhibit stable H₂ sensing within the ∼188–388 K temperature range, in which the critical temperature is ∼188 K. Comparatively, no temperature-activated “reverse sensing behavior” is observed in PdAu NTs with smooth surfaces (S-PdAu NTs). Theoretically, such stable H₂ sensing is interpreted as the tuned surfaces of NTs modulating the saturated adsorption of H₂, while the Pd nanostructures with Au dopant further improve the stability of H₂ sensing. Potentially, the approach to surface-tuned PdAu NTs could be expanded to other sensing materials for low-temperature gas sensing.