In this research, we report a series of new heterostructured hybrid 2D ZnO nanocomposites sensitized with Cu2O nanoparticles for sunlight photocatalysis. The Cu2O nanoparticles were synthesized by a surfactant-free method and size reduced by a solvothermal method. 2D ZnO/Cu2O composites were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, reflectance diffuse spectroscopy and Fourier transform infrared. The results showed that the product is a material comprised of layered hybrid 2D ZnO with cubic Cu2O nanoparticles. The photocatalytic activities of the composites were investigated for photodegradation of methylene blue solution as models' pollutant under sunlight irradiation. The photocatalytic efficiency of a 0.1:1 mixture of Cu2O nanoparticles with 2D ZnO showed that the degradation rate was faster than those of individual ZnO nanocomposites and bulk nanoparticles, respectively. The photocatalytic degradation mechanism studied using specific radical scavengers corroborates the synergy between both semiconductors in the composite and evidences a Z-scheme mechanism to explain the electron transfer. The catalytic reuse tests show that the presence of the ZnO nanocomposite avoids the typical corrosion of Cu2O.