The Synthesis of Z-Scheme MoS.sub.2/g-C.sub.3N.sub.4 Heterojunction for Enhanced Visible-Light-Driven Photoreduction of Uranium

Graphitic carbon nitride (g-C.sub.3N.sub.4) has been paid increasingly attentions in U(VI) removal due to the visible-light response, whereas the high recombination of photogenerated electron and holes limited the actual environmental application. Herein, Z-scheme MoS.sub.2/g-C.sub.3N.sub.4 heterojunction was fabricated to enhance removal of U(VI) from aqueous solution. The microscopic and spectroscopic characterizations showed that addition of MoS.sub.2 on surface of g-C.sub.3N.sub.4 increased separation efficiency of photogenerated charge, decreased the bandgap and improved the intensity of light adsorption. Approximate 82% of UO.sub.2.sup.2+ was photo-reduced by MoS.sub.2/g-C.sub.3N.sub.4 after 1 h of light irradiation at pH 4.5. The high effective photocatalytic reduction of U(VI) on MoS.sub.2/g-C.sub.3N.sub.4 was attributed to ·O.sub.2.sup.- radials according to quenching experiments. XPS analysis showed that the adsorbed U(VI) was photo-reduced into U(IV). These findings are crucial for the design of C.sub.3N.sub.4-based composites with high efficient photocatalytic performance and exclusive selectivity into actual environmental cleanup.