Fast detection of hydrogen gas leakage or its release
in different
environments, especially in large electric vehicle batteries, is a
major challenge for sensing applications. In this study, the morphological,
structural, chemical, optical, and electronic characterizations of
ZnO:Eu nanowire arrays are reported and discussed in detail. In particular,
the influence of different Eu concentrations during electrochemical
deposition was investigated together with the sensing properties and
mechanism. Surprisingly, by using only 10 μM Eu ions during
deposition, the value of the gas response increased by a factor of
nearly 130 compared to an undoped ZnO nanowire and we found an H2 gas response of ∼7860 for a single ZnO:Eu nanowire
device. Further, the synthesized nanowire sensors were tested with
ultraviolet (UV) light and a range of test gases, showing a UV responsiveness
of ∼12.8 and a good selectivity to 100 ppm H2 gas.
A dual-mode nanosensor is shown to detect UV/H2 gas simultaneously
for selective detection of H2 during UV irradiation and
its effect on the sensing mechanism. The nanowire sensing approach
here demonstrates the feasibility of using such small devices to detect
hydrogen leaks in harsh, small-scale environments, for example, stacked
battery packs in mobile applications. In addition, the results obtained
are supported through density functional theory-based simulations,
which highlight the importance of rare earth nanoparticles on the
oxide surface for improved sensitivity and selectivity of gas sensors,
even at room temperature, thereby allowing, for instance, lower power
consumption and denser deployment.