Photocatalytic and Photo-Fenton Catalytic Degradation Activities of Z-Scheme Ag(2)S/BiFeO(3) Heterojunction Composites under Visible-Light Irradiation

Z-scheme Ag(2)S/BiFeO(3) heterojunction composites were successfully prepared through a precipitation method. The morphology and microstructure characterization demonstrate that Ag(2)S nanoparticles (30–50 nm) are well-decorated on the surfaces of polyhedral BiFeO(3) particles (500–800 nm) to form Ag(2)S/BiFeO(3) heterojunctions. The photocatalytic and photo-Fenton catalytic activities of the as-derived Ag(2)S/BiFeO(3) heterojunction composites were evaluated by the degradation of methyl orange (MO) under visible-light irradiation. The photocatalytic result indicates that the Ag(2)S/BiFeO(3) composites exhibit much improved photocatalytic activities when compared with bare Ag(2)S and BiFeO(3). The optimum composite sample was observed to be 15% Ag(2)S/BiFeO(3) with an Ag(2)S mass fraction of 15%. Furthermore, the addition of H(2)O(2) can further enhance the dye degradation efficiency, which is due to the synergistic effects of photo- and Fenton catalysis. The results of photoelectrochemical and photoluminescence measurements suggest a greater separation of the photoexcited electron/hole pairs in the Ag(2)S/BiFeO(3) composites. According to the active species trapping experiments, the photocatalytic and photo-Fenton catalytic mechanisms of the Ag(2)S/BiFeO(3) composites were proposed and discussed.