  Semiconductor nanocrystals (NCs) are the building blocks for the future
opto-electronic devices, and other energy-harvesting applications. Although the
energy demand has been increasing, energy sources are diminishing. Hydrogen,
green energy source, is used in space shuttles and other transportation means.
The hydrogen production using semiconductors such as TiO2 suffers from several
limitations, and hence, alterative techniques for hydrogen production are
desired. Recently, photocatalysis using different nanostructures has been
studied.1-6 In this project, we have studied the catalytic activity of
gold/cadmium sulphide (Au/CdS) NCs to reduce protons into hydrogen
qualitatively. The Au/CdS NCs absorb a large amount of visible photons due to
plasmon resonance and create electron-hole pairs. The excited electrons migrate
to the catalysts, and the protons are reduced while the ligands on the surface
of NCs scavenge holes. Thus, photocatalysis occurs due to the energy transfer
from metal to semiconductor materials. The hydrogen production using Au/CdS
metal semiconductor NCs is more efficient than that of using CdS semiconductor
NCs.
