Cu-based nanocrystals on ZnO for uranium photoreduction: Plasmon-assisted activity and entropy-driven stability

Photoreduction of soluble U(VI) into insoluble U(IV) servers as a novel and efficient approach for U(VI) enrichment, where semiconductors are generally applied as the photocatalysts. Unfortunately, only a part of sunlight is utilized during the photoreduction process, significantly limiting the treatment performance for U(VI). Herein, we successfully constructed highly active and stable photocatalysts for the photo-assisted treatment of U(VI) by depositing Cu80Co5Ni5Cd5In5 nanocrystals on porous ZnO (CCNCI/ZnO) to efficiently expand the response region of sunlight. Impressively, the U(VI) enrichment capacity of CCNCI/ZnO was up to 2405.3 mg/g within 60 min. Moreover, CCNCI/ZnO exhibited excellent stability during photocatalysis due to the enhanced entropy of Cu80Co5Ni5Cd5In5 nanocrystals. Further mechanistic studies indicated that Cu80Co5Ni5Cd5In5 nanocrystals in CCNCI/ZnO generated hot electrons under visible light, followed by the transformation of hot electrons to porous ZnO via the Schottky barrier. Hot carriers efficiently reduced U(VI) over CCNCI/ZnO, contributing to the remarkable performance during U(VI) enrichment.