Laser-based investigation of the transition from droplets to nanoparticles in flame-assisted spray synthesis of functional nanoparticles

Chenyang Liu, Shuiqing Li, Yichen Zong, Qiang Yao, Stephen D. Tse

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Mechanisms involved in flame-assisted-spray-pyrolysis (FASP) synthesis of TiO2-based functional nanoparticles are investigated using in situ phase-selective laser-induced breakdown spectroscopy. Specifically, the transition from droplets to nanoparticles is examined, as well as the particle growth process in the post flame region. In contrast to vapor-fed flame synthesis, the existence of the precursor breakdown in sprayed droplets is observed by both Ti atomic signal and Bremsstrahlung emissions. The emission signal intensity variation reveals the transition from droplets to nanoparticles, indicating that the competition between precursor vaporization and nascent particle formation is the rate determining factor. For the ensuing particle growth regime, the prediction of the particle size evolution by a polydispersed population balance model is in good agreement with TEM and laser-diagnostics results, demonstrating that the particle growth is governed by the collision-coagulation mechanism. Besides, the transition from droplets to nanoparticles can be accelerated with sufficient OH radicles provided by combustible solvents. Furthermore, doping of TiO2 with V and Zr will lead to changes in band gap of the nanoparticle observed, i.e., a distinct strengthening by 23% with V doping and a weakening by 22% with Zr doping in the intensity of Ti signal, respectively.

Original languageEnglish (US)
Pages (from-to)1109-1117
Number of pages9
JournalProceedings of the Combustion Institute
Volume36
Issue number1
DOIs
StatePublished - 2017

All Science Journal Classification (ASJC) codes

  • General Chemical Engineering
  • Mechanical Engineering
  • Physical and Theoretical Chemistry

Keywords

  • Flame-assisted spray pyrolysis
  • Functional TiO-based nanoparticle
  • Phase-selective LIBS
  • Transition from droplets to nanoparticles

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