PHYSICOCHEMICAL AND CATALYTIC PROPERTIES OF GAMMA-IRRADIATED LANTHANUM NICKELATE (LANIO3)

Electronspin resonance (ESR) studies of gamma-irradiated LaNiO3 reveal ed the formation of chemisorbed superoxide ion (O-2(-)) and F centers (electrons trapped in anion vacancies). X-ray photoelectron spectrosco py (XPS) showed that the gamma-irradiation of LaNiO3 in the presence o f moisture leads to the reduction of the transition metal (Ni3+ to Ni2 +) which in turn facilitates the formation of O-2(-) and surface carbo nate species (CO32-). A qualitative molecular orbital model has been p roposed for the chemisorption of O-2(-) on the reduced transition meta l centers (Ni2+). The hydrated electron generated by the radiolysis of moisture reduces the transition metal. Gamma-irradiated LaNiO3 shows enhanced catalytic activity for the decomposition of hydrogen peroxide (H2O2) and the increase in catalytic activity is attributed to the re duced metal content. The formation of chemisorbed oxygen decreases the electrical conductivity by trapping the charge carriers.