Anchored MoS2 co-catalysts on ZnxCd1-xS solid solution for photocatalytic reduction of U(VI)

Abstract

In recent years, a great deal of attention has focused on achieving higher photocatalytic performance by modifications. However, external modification methods, such as heterojunction, defect engineering and doping, bring the disadvantage of mismatch of energy band positions or uncontrollable defects and doping positions, resulting in different photocatalytic efficiencies for different batches of materials. As a result, the search for new modification methods is currently the focus of photocatalytic reduction of U(VI). In this work, the modification method of forming a solid solution between Zn, Cd and S by adjusting the ratio of Zn /Cd precursors, i.e., the internal modification method, is proposed to solve the problem of matching the energy band structure, keeping the conduction band in the right position and facilitating efficient charge separation, and complexing with MoS2 co-catalysts to improve the catalytic performance of the catalyst. A novel complex, MoS2/Zn0.2Cd0.8S, has been designed and synthesized. And the photocatalytic reduction of U(VI) by Zn0.2Cd0.8S was 27 and 373 times higher than that of pure CdS and ZnS, respectively, and MoS2/Zn0.2Cd0.8S was 24.45 % higher than that of Zn0.2Cd0.8S (74.75 %), with a reduction rate of 99.20 % under 60 min of illumination. Gladly, its photocatalytic activity remained above 95.67 % after five cycles, and there was no difference in the performance of catalysts synthesised in different batches, showing excellent stability and reproducibility. Moreover, the mechanism of U(VI) reduction was investigated by MoS2/Zn0.2Cd0.8S. This study provides a new strategy to guarantee the preparation of photocatalysis with stable performance and improve photocatalytic performance.