Microwave-assisted one-step rapid synthesis of ternary Ag/Ag^sub 2^S/g-C^sub 3^N^sub 4^ heterojunction photocatalysts for improved visible-light induced photodegradation of organic pollutant

Constructing ternary plasmonic metal/semiconductor I/semiconductor II heterojunction is a promising approach to improve photocatalytic activity of semiconductor materials due to the effective inhibition for the recombination of photogenerated electron-hole pairs. Here, we report a microwave-assisted one-step rapid synthesis of ternary Ag/Ag2S/g-C3N4 heterojunction photocatalysts. In the one-step synthesis, Ag/Ag2S nanoparticles were deposited simultaneously on the surface of g-C3N4 within two minutes under atmospheric conditions. The robust semiconductor heterojunction was formed between Ag/Ag2S nanoparticles and g-C3N4 nanosheets. The resulting ternary heterojunction photocatalysts exhibited the enhanced visible-light absorption and the inhibited recombination of photogenerated electron-hole pairs due to surface plasmon resonance (SPR) and heterojunction effect. As a result, photocatalytic activity of the ternary Ag/Ag2S/g-C3N4 heterojunction photocatalysts was improved for photodegradation of rhodamine B (RhB) under visible-light irradiation. The optimum rate constant of the Ag/Ag2S/g-C3N4 heterojunction photocatalysts is 4.3 and 21.3 times higher than that of the raw g-C3N4 and the Ag/Ag2S. Based on the results of the active species trapping test, the mechanism of photocatalysis of the Ag/Ag2S/g-C3N4 heterojunction photocatalysts was also discussed.