Ternary heterojunctions synthesis and sensing mechanism of Pd/ZnO–SnO2 hollow nanofibers with enhanced H2 gas sensing properties

In this paper, Pd/ZnO–SnO2 hollow nanofibers prepared by electrospinning and magnetron sputtering. The sensing materials exhibited extraordinary hydrogen (H2) sensing behavior – the response reached 171 at 270 °C, and besides, the response time and recovery time were as low as 19 s and less than 1 s at 240 °C, with steady high selectivity and good repeatability. Such an enhanced sensing performance could be attributed to the Pd/ZnO/SnO2 ternary heterojunctions formed in the hollow nanofibers. Moreover, the materials were studied by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and especially the morphology formation process was further explained. The existence of Pd was confirmed to increase the resistance modulation range of heterojunction. In addition, the gas sensing mechanism based on the structure was proposed. The unique Pd/ZnO–SnO2 hollow nanofibers formed with ternary heterojunctions by electrospinning and annealing showed ultra-enhanced H2 gas sensing properties, providing a novelty method to fabricate high response, fast response and recovery and low LOD H2 gas sensors. [Display omitted] •Pd/ZnO–SnO2 hollow nanofibers formed with ternary heterojunctions was synthesized.•The formation process of hollow nanofiber morphology was analyzed.•Gas sensing mechanisms of the Pd/ZnO–SnO2 hollow nanofibers were proposed.•Pd/ZnO–SnO2 hollow nanofibers showed enhanced H2 gas sensing properties.