One-step synthesis of Ag6Si2O7/AgCl heterojunction composite with extraordinary visible-light photocatalytic activity and stability

In this paper, a Z-scheme Ag6Si2O7/AgCl heterojunction composite was successfully constructed via a one-step co-precipitation method and investigated as a novel photocatalyst for the first time. The as-prepared samples were thoroughly characterized by the FESEM, HRTEM, XRD, FTIR, DRS and XPS. The photocatalytic properties of the obtained samples were evaluated by monitoring the degradation efficiency of refractory organic pollutants (methyl orange (MO), rhodamine B (RhB) and phenol) and photocurrent intensity under visible-light irradiation. The Ag6Si2O7/AgCl photocatalysts showed drastically enhanced photocatalysis performance compared to the Ag6Si2O7 and AgCl. In particular, the 1/72 Ag6Si2O7/AgCl composite showed the highest photocatalytic activity, exhibiting a nearly complete degradation of 10 mg/L MO and 20 mg/L phenol within only 40 and 180 min, respectively. The enhancement of photocatalytic activity of the Ag6Si2O7/AgCl could be mainly attributed to (1) strong visible-light absorption capacity; (2) effective photogenerated charge separation and transfer through the coupled heterojunction interfaces of Ag6Si2O7 and AgCl. Moreover, a possible Z-scheme charge transfer mechanism was proposed based on the experimentation and the theoretical calculation. During the photocatalytic reaction, the Ag6Si2O7/AgCl photocatalyst exhibited high mineralization ability for organic pollutants, indicating that it had great practical value in the field of water treatment.