Towards the continuous hydrothermal synthesis of zno@mg2 al-co3 core-shell composite nanomaterials

Ian Clark, Jacob Smith, Rachel L. Gomes, Edward Lester*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Core-shell Zinc Oxide/Layered Double Hydroxide (ZnO@LDH) composite nanomaterials have been produced by a one-step continuous hydrothermal synthesis process, in an attempt to further enhance the application potential of layered double hydroxide (LDH) nanomaterials. The synthesis involves two hydrothermal reactors in series with the first producing a ZnO core and the second producing the Mg2 Al-CO3 shell. Crystal domain length of single phase ZnO and composite ZnO was 25 nm and 42 nm, respectively. The ZnO@LDH composite had a specific surface area of 76 m2 g−1, which was larger than ZnO or Mg2 Al-CO3 when produced separately (53 m2 g−1 and 58 m2 g−1, respectively). The increased specific surface area is attributed to the structural arrangement of the Mg2 Al-CO3 in the composite. Platelets are envisaged to nucleate on the core and grow outwards, thus reducing the face–face stacking that occurs in conventional Mg2 Al-CO3 synthesis. The Mg/Al ratio in the single phase LDH was close to the theoretical ratio of 2, but the Mg/Al ratio in the composite was 1.27 due to the formation of Zn2 Al-CO3 LDH from residual Zn2+ ions. NaOH concentration was also found to influence Mg/Al ratio, with lower NaOH resulting in a lower Mg/Al ratio. NaOH concentration also affected morphology and specific surface area, with reduced NaOH content in the second reaction stage causing a dramatic increase in specific surface area (>250 m2 g−1). The formation of a core-shell composite material was achieved through continuous synthesis; however, the final product was not entirely ZnO@Mg2 Al-CO3. The product contained a mixture of ZnO, Mg2 Al-CO3, Zn2 Al-CO3, and the composite material. Whilst further optimisation is required in order to remove other crystalline impurities from the synthesis, this research acts as a stepping stone towards the formation of composite materials via a one-step continuous synthesis.

Original languageEnglish (US)
Article number2052
Pages (from-to)1-15
Number of pages15
JournalNanomaterials
Volume10
Issue number10
DOIs
StatePublished - Oct 2020

Keywords

  • Composite
  • Continuous hydrothermal synthesis
  • Layered double hydroxide
  • Nano hybrid structures
  • Ultraviolet (UV) properties

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Materials Science(all)

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