Novel visible-light-driven graphitic carbon nitride (g-C3N4)/WO3 composite photocatalysts were prepared, and the acetaldehyde (CH3CHO) degradation activity of these composites was evaluated. The prepared g-C3N4/WO3 composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflection spectroscopy (UV-vis), and the N2 gas adsorption Brunauer-Emmett-Teller (BET) method (N2-BET). The WO3 particles, which were 100-300 nm in size, were in direct contact with the g-C3N4 sheet surface. The optical band gap and specific surface area of the g-C3N4/WO3 composites were in the range of 2.65-2.75 eV and 4-7 m(2)/g, respectively. The g-C3N4/WO3 composites exhibited higher activity for the photodegradation of CH3CHO under visible light irradiation compared to g-C3N4. The optimal WO3 content for the CH3CHO photodegradation activity of the heterojunction structures was determined. The synergistic effect of g-C3N4 and WO3 was considered to lead to improved photogenerated carrier separation. A possible degradation mechanism of CH3CHO over the g-C3N4/WO3 composite photocatalyst under visible light irradiation was proposed. These results should usefully expand applications of g-C3N4 as a visible-light-driven photocatalyst. (C) 2013 Elsevier B.V. All rights reserved.