Cuprous-Sulfide-Nanoplate-Catalyzed Click Chemistry for In Situ Construction of Covalent Organic Polymer Heterostructures for Efficient Photocatalytic Reduction and Removal of U(VI).

In this study, a core-shell heterostructure of cuprous sulfide (CuS) nanoplates and covalent organic polymers (COPs) (CuS@COP) was constructed in situ by a CuS-catalyzed azide-alkyne reaction for efficient reduction and rapid removal of U(VI) from uranium mine wastewater. The simple in situ synthesis of heterojunctions through click chemistry reactions can create a tight bond at the interface and evade the laborious process of conventional composites. The different Fermi energy levels of CuS and COP induce the formation of a built-in electric field within the core-shell heterojunction, and the photogenerated charge transfer from the COP to CuS nanoplate results in a substantial boost in the efficiency of the photocatalytic reduction of U(VI). The CuS@COP heterojunction demonstrates a high U(VI) removal capacity of 1164.6 mg g without the need of a sacrificial agent, which is 2.08 times higher than CuS nanoplates, 3.02 times higher than COP, and better than most other previous heterostructures. The present photocatalytic method involves good specificity and achieves a high U(VI) removal efficiency of 85.9% from uranium mine wastewater. The in situ preparation of the CuS@COP core-shell heterojunction via click chemistry provides a new design concept for composite construction and presents a novel strategy to modulate the photocatalytic activity for contaminant management.