IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Processing at the Nanoscale Monday Sessions
       Session PN-MoA

Paper PN-MoA7
Size Selective Electrochemical Growth of Molybdenum Disulfide Nanowires and Nanoparticles

Monday, October 29, 2001, 4:00 pm, Room 133

Session: Nanostructures from 0 to 3 Dimensions
Presenter: K.H. Ng, University of California, Irvine
Authors: K.H. Ng, University of California, Irvine
K. Inazu, University of California, Irvine
R.M. Penner, University of California, Irvine
J.C. Hemminger, University of California, Irvine
Correspondent: Click to Email
MoS@sub 2@ nanoparticles and nanowires having mean diameters ranging from 2 to 200 nm were synthesized on the basal plane and step edges of highly oriented pyrolytic graphic surface using an electrochemical/chemical (E/C) method. This method involves the following steps: (1) electrochemical deposition of molybdenum dioxide precursor nanostructures consisting of nanowires or nanoparticles onto an electrode surface, (2) displacement of oxygen in MoO@sub 2@ with sulfide by heating the sample at 500°C in H@sub 2@S. Each metal oxide nanostructure was converted into a semiconductor nanoparticle of the same shape and size as the original MoO@sub 2@ precursor nanostructure. Selected-area electron diffraction (SAED), energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS) confirm the formation of MoS@sub 2@ nanostructure. For MoS@sub 2@ nanostructure having a critical dimension larger than 20 nm, photoluminescence spectroscopic analysis showed a strong, room temperature emission peak around 2 eV which is consistent with the direct bandgap of this material. As the critical dimension was reduced from 20 to 2 nm, the energy of this emission shifted to higher energies qualitatively as predicted by the effective mass, strong confinement model.