Enhanced Visible Light Photocatalytic Performance of G-C3N4 Photocatalysts Co-Doped with Gold and Sulfur for Degradation of Persistent Pollutant (Rhodamine B).

In order to overcome the intrinsic drawback of pristine g-C₃N₄, a nano-composite photo-catalyst Au/S-C₃N₄ with controllable nanoscale gold (Au) particles was successfully synthesized by a facile liquid chemical preparation process. It was found that the content of chloroauric acid (AuCl₃ · HCl · 4H₂O) play crucial role in both the diameter and the density of the Au nanoparticles. The results showed that as-prepared Au/S-C₃N₄ nanosheets with 2 wt% Au loaded content exhibited excellent photocatalytic decomposition of RhB under visible light irradiation as compared with other Au loadings (i.e., 1 wt%, 2 wt%, 3 wt%, 4 wt% and 6 wt%). The photocatalytic activity of Au/S-C₃N₄ with 2 wt% Au loading was twice higher than that of bare S-C₃N₄ (0.00955 min). The enhanced performance could be attributed to the synergic effect of gold and sulfur on g-C₃N₄. A possible mechanism for elucidating the better performance of Au/S-C₃N₄ is also proposed and discussed in detail in this work.