Enhanced visible light photocatalytic activity of novel polymeric g-C3N4 loaded with Ag nanoparticles

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 Ag0 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 μmol 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.