Hybrid paper-TiO2 coupled with a Cu2O heterojunction: an efficient photocatalyst under sun-light irradiation

Hybrid paper-TiO2, paper-Cu2O-TiO2 and paper-TiO2-Cu2O photocatalysts were prepared via a nonhydrolytic sol-gel process followed by mild hydrothermal treatment to generate the TiO2 layer, and a reduction process to form the Cu2O nanoparticles. The hybrid photocatalysts have been characterized by Raman, TGA, FE-SEM, UV-Vis and XPS. The immobilized TiO2 was found to form a homogeneous thin layer composed of nanoparticles with a size smaller than 10 nm. The Cu2O nanoparticles with sizes of 30-100 nm were generated either on the top of the TiO2 layer or by reduction of Cu2+ ions. All the prepared hybrid catalysts showed efficient photocatalytic properties for the degradation of toluidine when exposed to simulant solar light. A strong enhancement in the photocatalytic activity was observed when TiO2 was coupled with the Cu2O heterojunction, with the highest effect being observed when the Cu2O NPs were present on top of the TiO2 layer. The hybrid photocatalyst can be reused for at least four consecutive cycles without a significant decrease in the degradation efficiency. The preparation technique of the hybrid catalyst is reliable, economic, easy to implement and may be scaled to prepare paper-TiO2 hybrid photocatalysts active under sun-light exposure.