Heterogeneous nucleation for synthesis of sub-20nm ZnO nanopods and their application to optical humidity sensing

R. Majithia, S. Ritter, K. E. Meissner

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


We present a novel method for colloidal synthesis of one-dimensional ZnO nanopods by heterogeneous nucleation on zero-dimensional ZnO nanoparticle 'seeds'. Ultra-small ZnO nanopods, multi-legged structures with sub-20. nm individual leg diameters, can be synthesized by hydrolysis of a Zn2+ precursor growth solution in presence of ~4. nm ZnO seeds under hydrothermal conditions via microwave-assisted heating in as little as 20. min of reaction time. One-dimensional ZnO nanorods are initially generated in the reaction mixture by heterogeneous nucleation and growth along the [0001] direction of the ZnO crystal. Growth of one-dimensional nanorods subsequently yields to an 'attachment' and size-focusing phase where individual nanorods fuse together to form multi-legged nanopods having diameters ~15. nm. ZnO nanopods exhibit broad orange-red defect-related photoluminescence in addition to a near-band edge emission at 373. nm when excited above the band-gap at 350. nm. The defect-related photoluminescence of the ZnO nanopods has been applied towards reversible optical humidity sensing at room temperature. The sensors demonstrated a linear response between 22% and 70% relative humidity with a 0.4% increase in optical intensity per % change in relative humidity. Due to their ultra-small dimensions, ZnO nanopods exhibit a large dynamic range and enhanced sensitivity to changes in ambient humidity, thus showcasing their ability as a platform for optical environmental sensing.

Original languageEnglish (US)
Pages (from-to)206-214
Number of pages9
JournalAnalytica Chimica Acta
StatePublished - Feb 17 2014

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Biochemistry
  • Environmental Chemistry
  • Spectroscopy


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