Fullerol (polyhydroxyfullerene, PHF) has shown favorable electron accepting properties in semiconductor photocatalytic systems, but little is known about the possibility of electron transfer mediation of PHF in heterogeneous photo-Fenton processes. This work intends to investigate the effect of PHF on the heterogeneous photo-Fenton activity of ferrihydrite (Fh). PHF/ferrihydrite (PHF/Fh) composites were prepared and their photo-Fenton activities in the degradation of acid red 18 under simulated sunlight irradiation were examined. The structural characteristics of the as-synthesized samples were studied using XRD, SEM-EDS, SPM, DRS, and N-2 adsorption-desorption. The results showed that PHF/Fh had much higher catalytic activities than Fh, and appropriate contents of PHF on PHF/Fh could enhance the stability of Fh. In addition, the presence of PHF on PHF/Fh could enhance the production of O-1(2) and (OH)-O-center dot as compared with pure Fh. We propose that the excited state PHF could efficiently sensitize the ground state O-2 to generate O-1(2), and at the same time could transfer electrons to the Fe3+ on Fh, leading to an accelerated reduction of Fe3+ to Fe2+. As a result, the decomposition of H2O2 (by Fe2+) into (OH)-O-center dot could be promoted as well. On the other hand, based on the results of GAMESS calculation and GC-MS analysis, the degradation pathway of AR18 was further proposed. (C) 2016 Elsevier B.V. All rights reserved.