Studies of photoredox reactions on nanosize semiconductors

Conference · Fri Aug 01 04:00:00 EDT 1997

OSTI ID:510299

Wilcoxon, J P ^[1]; Parsapour, F; Kelley, D F ^[2]

---

1. Sandia National Labs., Albuquerque, NM (United States)
2. Colorado State Univ., Fort Collins, CO (United States). Dept. of Chemistry

Light induced electron transfer (ET) from nanosize semiconductors of MoS{sub 2} to organic electron acceptors such as 2,2{prime}-bipyridine (bpy) and methyl substituted 4,4{prime},5,5{prime}-tetramethyl-2,2{prime}-bipyridine (tmb) was studied by static and time resolved photoluminescence spectroscopy. The kinetics of ET were varied by changing the nanocluster size (the band gap), the electron acceptor, and the polarity of the solvent. MoS{sub 2} is an especially interesting semiconductor material as it is an indirect semiconductor in bulk form, and has a layered covalent bonding arrangement which is highly resistant to photocorrosion. Et occurs following photoexcitation of the direct band gap. Quantum confinement results in the smaller nanoclusters having higher conduction band energies, and therefore larger ET driving forces. The ET reaction energies may be varied by changing the electron acceptor, by varying the size of the MoS{sub 2} nanocluster or by varying the polarity of the solvent. In addition, varying the polarity of the solvent affects the reorganization energy and the barrier to electron transfer. TMB is harder to reduce, and thus has a smaller ET driving force than bpy. The solvent polarity is varied by varying the composition of acetonitrile/benzene mixed solvents.

• Research Organization: Sandia National Labs., Albuquerque, NM (United States)
• Sponsoring Organization: USDOE Office of Environmental Restoration and Waste Management, Washington, DC (United States)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 510299
• Report Number(s): SAND--97-1465C; CONF-970517--9; ON: DE97006874
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
BIPYRIDINES
ELECTRON TRANSFER
ELECTRONIC STRUCTURE
MOLYBDENUM SULFIDES
OPTICAL PROPERTIES
PARTICLE SIZE
PHOTOCHEMICAL REACTIONS
QUANTUM EFFICIENCY
REDOX REACTIONS