|
With hydrogen being accepted as fuel for the future, the world is looking forward to development of clean and
sustainable methods of its production from renewable energy. In this context, area of research in the PEC splitting of
water assumes great significance and the challenge is to develop corrosion resistant, chemically stable semiconductor
that absorbs sunlight in the visible region and also has the band edges matching to the redox level of water. The advent
of nanotechnology has opened new vistas in the production of semiconductor with large surface area for solar energy
absorption and other favourable properties, which has lead to restudy the old workhorses, viz α-Fe2O3 and TiO2 in the
PEC splitting of water. This communication reports the study on metal oxides, towards the photoelectrochemical
splitting of water as function of material properties and characteristics of semiconductor- electrolyte junction, viz;
particle size, suitable dopants, crystalline phase, surface morphology, resistivity, bandgap, donor density and flatband
potential. Effect of sensitizers and surface modification has also been investigated. Both the techniques of surface
modification: (i) depositing metal dots and (ii) swift heavy ion irradiation in α-Fe2O3 were observed to be much effective
in improving the photoresponse of the material. α-Fe2O3 thin films prepared using spray pyrolysis having Zn dots (dot
height: 260 Å) on its surface exhibited the best of photocurrent density (1.82 mA/cm2), at 0.6 V applied bias. Nitrogen
doped nanostructured TiO2 prepared by sol gel method exhibited much better photoresponse as compared to any other
dopant.
|
