Sulfur Dioxide and Nitrogen Dioxide Adsorption on Zinc Oxide and Zirconium Hydroxide Nanoparticles and the Effect on Photoluminescence
Abstract
Nanoparticulate zinc oxide and micron-size zirconium hydroxide powders have been exposed to sulfur dioxide and nitrogen dioxide by flowing the gases, diluted with nitrogen, over powder samples. X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and thermal gravimetric analyses (TGA) indicate strongly bound, chemisorbed SO3 and NO3 surface species. Two pre-treatments of the nanoparticulate ZnO samples prior to gas exposure have been investigated: 1) drying overnight in a vacuum oven and 2) hydrating the samples by placing them overnight in water-saturated air. A dramatic difference in reactivity of ZnO is observed, with approximately two-fold and ten-fold greater uptake of NO2 and SO2, respectively, measured by XPS for the hydrated samples relative to the dried ones. Transmission electron microscopy (TEM) demonstrates that the greater uptake arises from a morphology change in the case of the hydrated samples, and it is postulated that this is due to dissolution of the gases in physisorbed water, which leads to acids that partially erode the ZnO and lead to greater surface area. For zirconium hydroxide, no morphology change is observed for hydrated samples, and SO4 (ads), in addition to SO3 (ads), is indicated by XPS. ZnO and Zr(OH)4 both exhibit photoluminescence (PL) spectra, with peak intensities that change dramatically due to hydration and subsequent exposure to SO2 and NO2 gases. Dosing of the powders with these gases effectively reverts the PL spectra to those corresponding to less hydration.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2012
- Accession Number
- ADA581674
Entities
People
- Anupama Mukherjee
- Gregory W. Peterson
- Jagdeep Singh
- James E. Whitten
- Jisun Im
- Sandip K. Sengupta
Organizations
- University of Massachusetts Lowell