In this study, heterojunctions of gold (Au) nanoparticles with three different average sizes (26, 20, and 12 nm in diameter), graphitic carbon nitride (g-C3N4) sheets, and rhombohedral hematite (Fe2O3) hybrid photocatalysts were fabricated via sonication at room temperature and used in the degradation of rhodamine B (RhB) dye under visible irradiation. The Au sensitized g-C3N4/Fe2O3 hybrid photocatalyst using 12 nm-sized Au particles, exhibited apparent rate constant of 31.6 x10(-3) min(-1), nearly 19-fold higher than that of pure hematite (Fe2O3 = 1.7 x 10(-3) min(-1)), and higher than those of the other hybrid samples. The superior performance of the Au/g-C3N4/Fe2O3 hybrid was attributed to a potential energy level difference, high optical absorbance, and the effective separation of photogenerated charge carriers. Additionally, the Au sensitized g-C3N4/Fe2O3 hybrid using 12 nm-sized Au particles, showed the highest specific surface area (46.5 m(2) g(-1)), compared with that of pure Fe2O3 (5.5 m(2) g(-1)) and g-C3N4/Fe2O3 (29.7 m(2) g(-1)) hybrid photocatalysts, showing numerous available sites for dye adsorption and degradation. Moreover, the transient photoresponse and open-circuit voltage decay clearly showed a high photocurrent and longer charge carrier lifetime, respectively. Reusability tests confirmed that the Au/g-C3N4/Fe2O3 hybrid photocatalyst was highly stable and recyclable. Hence, the work presented demonstrates the efficient, stable Au/g-C3N4/Fe2O3 hybrid photocatalyst for degradation of toxic pollutants under visible irradiation. (C) 2015 Elsevier B.V. All rights reserved.