Topochemical Transformation of Two-Dimensional VSe<sub>2</sub> into Metallic Nonlayered VO<sub>2</sub> for Water Splitting Reactions in Acidic and Alkaline Media.
basic_science · Level V
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- Record sourced from PubMed, PMID 34939404.
- Also identified by DOI 10.1021/acsnano.1c06662.
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Abstract
The engineering of the structural and morphological properties of nanomaterials is a fundamental aspect to attain desired performance in energy storage/conversion systems and multifunctional composites. We report the synthesis of room temperature-stable metallic rutile VO<sub>2</sub> (VO<sub>2</sub> (R)) nanosheets by topochemically transforming liquid-phase exfoliated VSe<sub>2</sub> in a reductive Ar-H<sub>2</sub> atmosphere. The as-produced VO<sub>2</sub> (R) represents an example of two-dimensional (2D) nonlayered materials, whose bulk counterparts do not have a layered structure composed by layers held together by van der Waals force or electrostatic forces between charged layers and counterbalancing ions amid them. By pretreating the VSe<sub>2</sub> nanosheets by O<sub>2</sub> plasma, the resulting 2D VO<sub>2</sub> (R) nanosheets exhibit a porous morphology that increases the material specific surface area while introducing defective sites. The as-synthesized porous (holey)-VO<sub>2</sub> (R) nanosheets are investigated as metallic catalysts for the water splitting reactions in both acidic and alkaline media, reaching a maximum mass activity of 972.3 A g<sup>-1</sup> at -0.300 V vs RHE for the hydrogen evolution reaction (HER) in 0.5 M H<sub>2</sub>SO<sub>4</sub> (faradaic efficiency = 100%, overpotential for the HER at 10 mA cm<sup>-2</sup> = 0.184 V) and a mass activity (calculated for a non 100% faradaic efficiency) of 745.9 A g<sup>-1</sup> at +1.580 V vs RHE for the oxygen evolution reaction (OER) in 1 M KOH (overpotential for the OER at 10 mA cm<sup>-2</sup> = 0.209 V). By demonstrating proof-of-concept electrolyzers, our results show the possibility to synthesize special material phases through topochemical conversion of 2D materials for advanced energy-related applications.