High-Resolution, Fast, and Shape-Conformable Hydrogen Sensor Platform: Polymer Nanofiber Yarn Coupled with Nanograined Pd@Pt.
basic_science · Level V
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- Record sourced from PubMed, PMID 31063349.
- Also identified by DOI 10.1021/acsnano.9b02481.
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Abstract
We report a flexible hydrogen sensing platform based on a single-strand yarn consisting of high-density electrospun nanofibers, on which nanograined Pd or Pd@Pt is coated via yarn spinning followed by sputter deposition. In general, Pd undergoes a phase transition to PdH <sub>x</sub> (α-PdH <sub>x</sub> at [H<sub>2</sub>] < 1% and β-PdH <sub>x</sub> at [H<sub>2</sub>] > 2%), in which H atoms act as electron scattering centers, thus increasing the resistance. In our system, the sensors exhibit switchable H<sub>2</sub> sensing behaviors, that is, (i) Δ R/ R<sub>0</sub> > 0 at [H<sub>2</sub>] > 1% by the active electron scattering and (ii) Δ R/ R<sub>0</sub> < 0 at [H<sub>2</sub>] < 1% derived from nanograined Pd effects. Due to high mechanical stability stemming from nanogranular morphologies of Pd, which is essential for enduring a huge volume expansion upon exposure to high-concentration H<sub>2</sub>, we could obtain a wide concentration range (4-0.0001%) H<sub>2</sub> detection resolution. Moreover, an ultrathin Pt overlayer coated on Pd offers an accelerated H<sub>2</sub> detection capability based on effective gas dissociation and activation properties. Furthermore, by virtue of the core (thread)-shell (nanofiber yarn) scaffold, long cycling reliability and flexibility were achieved. This facile and low-cost yarn fabrication method offers the development of single-strand thread-type wearable chemiresistors that possess a high surface area and open porosity, facilitating gas diffusion and reaction.