Visible light degradation of Orange II using xCu@dyO@dz/TiO@d2 heterojunctions

Cu@d2O/TiO@d2, Cu/Cu@d2O/TiO@d2 and Cu/Cu@d2O/CuO/TiO@d2 heterojunctions were prepared and studied for their potential application as photocatalysts able to induce high performance under visible light. Orange II was used as a representative dye molecule. The effect of the amount and composition of the photosensitizers toward the activation of TiO@d2 was studied. In each case, the global mechanism of Inter Particle Electrons Injection (IPEI) was discussed. The highest photocatalytic activity was observed for the system Cu/Cu@d2O/CuO (MB2 catalyst) under visible light (t@d1@d /@d2=24min, k=159.7x10@u-@u3min@u-@u1) and for the heterojunction cascade Cu/Cu@d2O/CuO/TiO@d2 (MB2 (50%)/TiO@d2) under UV-vis light (t@d1@d/@d2=4min, k=1342x10@u-@u3min@u-@u1). In the last case, the high performance was attributed firstly to the electromotive forces developed under this configuration in which CuO energy bands mediate the electrons transfer from Cu@d2O to TiO@d2. The formation of monobloc sensitizers also accounts for the decrease of the probability of the charges lost. It was demonstrated that ''Cu@d2O /CuO'' governs the capability of the heterojunction cascade and Cu does not play a significant role regardless of the heterojunction cascade efficiency. The electrical energy consumption per order of magnitude for photocatalytic degradation of Orange II was investigated for some representative catalytic systems. Visible/MB2 and UV/vis MB2 (50%)/TiO@d2 exhibited respectively 0.340 and 0.05 kWhm@u-@u3 demonstrating the high efficiency of the systems.