Synthesis of EDTA-bridged CdS/g-C3N4 heterostructure photocatalyst with enhanced performance for photoredox reactions

Photocatalytic reactions represent a kind of green and sustainable chemical processes for organic transformations, but the efficiency is limited by the severe recombination and/or inadequate redox potentials of photoinduced charge carriers in photocatalysts. To address these issues, herein, the CdS-EDTA/g-C3N4 heterostructures were designed according to Z-scheme photocatalytic mechanism and synthesized by the hydrothermal growth of CdS on g-C3N4 nanoflakes with assistance of EDTA chelating agent. EDTA played multiple roles in the formation of CdS-EDTA/g-C3N4 heterostructure photocatalysts, such as controlling the morphology of CdS nanostructures, linking CdS and g-C3N4 together, and boosting the charge transfer between two semiconductors. The optimized CdS-EDTA/g-C3N4 (10%) photocatalyst exhibited much higher activities toward the selective reduction of nitrophenol and the selective oxidation of benzyl alcohol, than those of CdS/g-C3N4 heterostructures without EDTA. The enhanced photocatalysis of CdS-EDTA/g-C3N4 can be ascribed to the efficient separation and suitable photoredox potentials of photoexcited charge carriers in the EDTA-bridged Z-scheme system. This work provides the inspiration for exploring inexpensive organic electron mediators for constructing all-solid-state Z-scheme photocatalysts and demonstrates the enhanced performance of Z-scheme photocatalysts for photoredox reactions of organic transformations. (C) 2020 Elsevier Inc. All rights reserved.