Yeast-derived carbon sphere as a bridge of charge carriers towards to enhanced photocatalytic activity of 2D/2D Cu2WS4/g-C3N4 heterojunction.

It is very challenging to fabricate novel, high-efficiency photocatalysts with an enhanced visible light absorption capacity, high charge carrier separation efficiency, and large specific surface area. For this purpose, a yeast-derived carbon (YC) sphere was added as a charge carrier bridge to the 2D-2D Cu2WS4/g-C3N4 heterojunction through a facile hydrothermal method. The YC sphere, as a bridge for electrons, is not only advantageous in inhibiting rapid recombination by electrons, but also remarkably enhances the visible light absorption capacity. Moreover, the YC sphere can also increase the specific surface area and surface roughness, which can enhance the adsorption of pollutant molecules and provide abundant active sites for photocatalytic reactions. The g-C3N4/YC/Cu2WS4 heterojunction showed the best photocatalytic activity for reducing hexavalent chromium Cr(VI) and decomposing tetracycline (TC) under visible light. Meanwhile, the acute toxicity of Daphnia magna (D. magna) gradually decreases with the conversion of Cr(VI) to Cr(III) in solution. In addition, the possible intermediate products and the photocatalytic reaction mechanism are revealed in depth. This work provides a general example for improving the photocatalytic activity of 2D-2D based heterojunctions by introducing a biomass material.