Photocatalytic splitting of water on NiO/InTaO4 catalysts prepared by an innovative sol–gel method Original Research Article

InTaO4 is a photocatalyst with visible-light response that is used to split water and produce hydrogen. InTaO4 is traditionally prepared by solid-state fusion of In2O3 and Ta2O5 at ≥1100 °C. A sol–gel procedure was developed to synthesize InTaO4 from In(NO3)3 and Ta(OC4H9)5 precursors. A uniform crystalline InTaO4 phase was easily obtained on calcination at 1100 °C because the sol–gel method allows homogeneous liquid-phase mixing. The method yields small InTaO4 particles with a high specific surface area. InTaO4 catalysts with different Ni loading were prepared by incipient wetness impregnation. Ni loading greatly enhanced the initial rate of H2 production during photocatalytic splitting of water. Ni metal within Ni–NiO core/shell nanoparticles can efficiently transfer photoelectrons on the InTaO4 surface and thus reduce H+ to hydrogen. NiOx/InTaO4 was deactivated due to the formation of Ni(OH)2. Overall, NiOx/InTaO4 prepared by the sol–gel method had higher activity than catalysts prepared by solid-state fusion. Among all the photocatalysts, 3.0 wt.% NiOx/InTaO4 exhibited the highest photoactivity, with an initial rate of H2 production of 2.10 μmol/g h.