Novel polymeric g-C3N4 photocatalysts loaded with noble metal Ag nanoparticles were prepared via a facile heating method. The obtained Ag/g-C3N4 composite products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM). X-ray photoelectron spectroscopy (XPS). UV-vis diffuse reflection spectra (DRS) and photoluminescence spectra (PL). The photocatalytic activities of Ag/g-C3N4 samples were investigated based on the decomposition of methyl orange and hydrogen evolution under visible light irradiation. The XPS results revealed that it was the metallic Ag-0 deposited on polymeric g-C3N4 samples. The Ag/g-C3N4 photocatalysts exhibited significantly enhanced photocatalytic performance for the degradation of methyl orange and hydrogen production compared with pure g-C3N4. The optimal Ag content was determined to be 1.0 wt%, and the corresponding hydrogen evolution rate was 10.105 mu mol h(-1), which exceeded that of pure g-C3N4 by more than 11.7 times. The enhanced photocatalytic performance could be attributed to the synergic effect between Ag and g-C3N4, which promoted the migration efficiency of photo-generated carriers. The proposed mechanism for the enhanced visible light photocatalytic activity of g-C3N4 modified by a small amount of Ag was further confirmed by photoluminescence spectroscopy. (C) 2011 Elsevier B.V. All rights reserved.