Construction of direct Z-scheme DUT-67/Fe2O3 heterostructures for efficient photoreduction of Cr(VI)

Photoreduction of toxic Cr(VI) in wastewater to less toxic Cr(III) presents an effective approach to address the environmental issues. Nevertheless, the photocatalytic performance of these photocatalysts is severely constrained by their narrow light absorption range and the rapid recombination of photo-generated electrons and holes. Herein, DUT-67/Fe 2 O 3 heterojunction photocatalysts were prepared by a simple mechanical grinding method. The formation of DUT-67/Fe 2 O 3 heterostructures not only increased the specific surface area and light absorption range, but also improved the separation of photogenerated charge carriers. Compared to the pristine DUT-67, DUT-67/Fe 2 O 3 exhibited significantly improved photocatalytic performance in the reduction of Cr(VI), achieving a reduction efficiency of up to 94 % within 40 min. Active species trapping experiments identified that electrons served as the primary species in the photocatalytic process. Coupled with electron spin resonance and density functional theory (DFT) calculations, a comprehensive mechanism for the photocatalytic reduction of Cr(VI) by DUT-67/Fe 2 O 3 Z-scheme heterojunction was proposed. This work offers new insights into the underlying mechanisms involving in the interfacial charge transfer and Cr(VI) photoreduction processes.