g-CN/Ag@AgCl with Z-scheme heterojunction and Ag electron bridge for enhanced photocatalytic degradation of tetracycline wastewater.

Building Z-scheme heterojunctions with an electron bridge is a favored function for increasing photocatalytic activity. A facile approach for preparing g-CN/Ag@AgCl ternary heterojunctions by co-precipitation and photoreduction was established in this work. First, via co-precipitation, AgCl was modified on the surface of g-CN to create a broad contact area between AgCl and g-CN. The AgCl is then reduced to Ag via an in-situ photoreduction technique, resulting in the formation of a ternary composite. The experimental results showed that when g-CN modified 25% of the Ag@AgCl, that is, g-CN/Ag@AgCl-25 had the best photocatalytic performance, 94.9% of TC was degraded within 240 min, and the reaction rate to TC was 0.1214 min, which was 4.49 times and 8.12 times higher than that of g-CN and Ag/AgCl, respectively. The excellent photocatalytic performance of g-CN/Ag@AgCl is attributed to the LSPR effect of Ag NPs and O-doping g-CN, which broadens the absorbance performance of g-CN, the establishment of Z-type heterojunctions between AgCl NPs and g-CN NSs and Ag NPs as an electron transport bridge accelerate the photogenerated electrons transfer between AgCl and g-CN.