The objective of this research was to prepare, characterize and evaluate the conversion efficiency of CO2 to fuel on a ZnO/g-C3N4 composite photocatalyst under simulated sunlight irradiation. The photocatalyst was synthesized by a simple impregnation method and was characterized by various techniques, including Brunauer-Emmett-Teller method (BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The characterizations indicate that ZnO and g-C3N4 were uniformly combined. The deposition of ZnO on g-C3N4 showed nearly no effect on its light-absorption performance. However, the interactions between the two components promoted the formation of a hetero-junction structure in the composite, inhibited the recombination of electron-hole pairs and, finally, enhanced the photocatalytic performance of ZnO/g-C3N4. The optimal ZnO/g-C3N4 photocatalyst showed a CO2 conversion rate of 45.6 mu mol h(-1) g(cat)(-1), which was 4.9 and 6.4 times higher than those of g-C3N4 and P25, respectively. This work represents an important step toward artificial photocatalytic CO2 conversion to fuel using cost-efficient materials. (C) 2014 Elsevier B.V. All rights reserved.