Efficient visible light photocatalytic activity of p–n junction CuO/TiO2 loaded on natural zeolite

Abstract

Highly efficient and visible-light-responsive p–n junction CuO/TiO₂-zeolite heterogeneous nanostructures had been successfully synthesized by a standard impregnation method. A detailed study of p–n junction CuO/TiO₂-zeolite impacting on the photodecoloration of a MB solution showed that the composite was highly reusable and stable for long-running photocatalytic application. The apparent rate constant of the CuO/TiO₂-zeolite was calculated to be 0.0704 min⁻¹, which is 1.4 times higher than that of TiO₂-zeolite (k = 0.048 min⁻¹) and 1.9 times higher than that of zeolite (k = 0.0368 min⁻¹). The experimental results indicated that the composites had a superior photocatalytic activity for the decoloration of dye wastewater under visible light irradiation because the p–n junction was formed between CuO and TiO₂. The assembly of p-type CuO produces a large number of p–n junction heterostructures on the surface of TiO₂, where CuO and TiO₂ form p- and n-type semiconductors, respectively. The p–n junction could efficiently suppress charge recombination, improve interfacial charge transfer, enhance visible-light adsorption and provide plentiful photocatalytic reaction active sites. This new p–n junction heteronanostructure is expected to show considerable potential application in solar-driven wastewater treatment.