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The batch removal of hexavalent chromium Cr(VI) from aqueous solutions is successfully achieved over the new hetero-system La2NiO4/TiO2 at pH ~ 4 under solar light. La2NiO4 is a direct band gap semiconductor with an optical transition of 1.30 eV. The photo-electrochemical characterization of the sensitizer La2NiO4 is undertaken to predict the electrons injection in TiO2 which acts as electrons bridge to adsorbed HCrO4-. The Mott Schottky of La2NiO4 plot is characteristic of p-type conductivity with a flat band potential of -0.37 V/SCE, more cathodic than that of TiO2. The photoactivity is strongly enhanced in presence of oxalic acid as hole scavenger. The saturation is due to Cr3+ oxidation by photoholes and the competitive water reduction. The re-utilization shows a negligible deactivation effect and the hetero-system could be promising for the water depollution.
