Near-Barrierless Ammonium Bisulfate Formation via a Loop-Structure Promoted Proton-Transfer Mechanism on the Surface of Water

Lei Li, Manoj Kumar, Chongqin Zhu, Jie Zhong, Joseph S. Francisco, Xiao Cheng Zeng

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

In the atmosphere, a well-known and conventional pathway toward the formation of ammonium sulfate is through the neutralization of sulfuric acid with ammonia (NH3) in water droplets. Here, we present direct ab initio molecular dynamics simulation evidence of the formation of ammonium bisulfate (NH4HSO4) from the hydrated NH3 and SO3 molecules in a water trimer as well as on the surface of a water droplet. This reaction suggests a new mechanism for the formation of ammonium sulfate in the atmosphere, especially when the concentration of NH3 is high (e.g., 10 μg m-3) in the air. Contrary to the water monomer and dimer, the water trimer enables near-barrierless proton transfer via the formation of a unique loop structure around the reaction center. The formation of the loop structure promotes the splitting of a water molecule in the proton-transfer center, resulting in the generation a NH4+/HSO4- ion pair. The loop-structure promoted proton-transfer mechanism is expected to be ubiquitous on the surface of cloud droplets with adsorbed NH3 and SO3 molecules and, thus, may play an important role in the nucleation of aerosol particles (e.g., fine particles PM2.5) in water droplets.

Original languageEnglish (US)
Pages (from-to)1816-1819
Number of pages4
JournalJournal of the American Chemical Society
Volume138
Issue number6
DOIs
StatePublished - Feb 17 2016

Fingerprint

Proton transfer
Protons
Water
Ammonium Sulfate
Atmosphere
Particles (particulate matter)
Molecules
Molecular Dynamics Simulation
ammonium bisulfate
Aerosols
Sulfuric acid
Ammonia
Dimers
Molecular dynamics
Nucleation
Monomers
Air
Ions
Computer simulation

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Near-Barrierless Ammonium Bisulfate Formation via a Loop-Structure Promoted Proton-Transfer Mechanism on the Surface of Water. / Li, Lei; Kumar, Manoj; Zhu, Chongqin; Zhong, Jie; Francisco, Joseph S.; Zeng, Xiao Cheng.

In: Journal of the American Chemical Society, Vol. 138, No. 6, 17.02.2016, p. 1816-1819.

Research output: Contribution to journalArticle

Li, Lei ; Kumar, Manoj ; Zhu, Chongqin ; Zhong, Jie ; Francisco, Joseph S. ; Zeng, Xiao Cheng. / Near-Barrierless Ammonium Bisulfate Formation via a Loop-Structure Promoted Proton-Transfer Mechanism on the Surface of Water. In: Journal of the American Chemical Society. 2016 ; Vol. 138, No. 6. pp. 1816-1819.
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