Ni2+ reduction under solar irradiation over CuFe2O4/TiO2 catalysts

The photo-electrochemical characterization of the hetero-system CoFe2O4/TiO2 was undertaken for the Ni2+ reduction under solar light. The spinel CoFe2O4 was prepared by nitrate route at 940 °C and the optical gap (1.66 eV) was well matched to the sun spectrum. The flat band potential (-0.21 VSCE) is more cathodic than the potential of Ni2+/Ni couple (-0.6 VSCE), thus leading to a feasible nickel photoreduction. TiO2 with a gap of 3.2 eV is used to mediate the electrons transfer. The reaction is achieved in batch configuration and is optimized with respect to Ni2+ concentration (30 ppm); a reduction percentage of 72% is obtained under sunlight, the Ni2+ reduction is strongly enhanced and follows a first order kinetic with a rate constant of 4.6×10-2 min-1 according to the Langmuir-Hinshelwood model.