Abstract
Decomposition of nickel nitrate hexahydrate in the presence of rod-shape anatase TiO(2) nanocrystals led to the formation of NiO-TiO(2) heteronanocrystals confirmed with powder X-ray diffraction and electron microscopy. The heteronanocrystals were supported on amorphous fumed silica to provide a heterogeneous photocatalyst material SiO(2)/NiO-TiO(2). The aqueous suspension of the catalyst, under argon atmosphere, irradiated with a Xe arc lamp led to the formation of H(2)O(2) with trace gaseous product formation. We observed an initial rate of formation of H(2)O(2) of 1.8 μmol g(-1) min(-1) that decays toward a steady-state concentration of 52 μM. Addition of AgNO(3) to the aqueous suspension gave fast reduction of silver ion, and higher initial rates of formation and steady state concentrations of H(2)O(2). We report the concentration dependence of water oxidation versus [AgNO(3)] with the fastest initial rate of formation of H(2)O(2) as 9.1 μmol g(-1) min(-1) and a steady-state concentration of 174 μM.