Effects Of The Uv Laser Radiation On The Surface Defects Of The Nio Catalysts.

NiO is a metal-deficient p-type semiconductor with surface defects which are correlated with the non-stoichiometry. The dissociative Hz adsorption on the NiO surface takes place on oxygen-excess sites (over equilibrium). The H-2 TPD spectra vary significantly with calcination temperature (stoichiometry) and chemical treatment. UV laser radiation enhances H-2 adsorption on the defective surfaces (non-stoichiometric) as compared with the stoichiometric ones, even chemically treated.The fourth harmonic (FH) of a Q-switched Nd:YAG laser is used for the NiO samples irradiation The wavelength of the UV laser radiation is 266nm, under the band-gap of the semiconductor.