Rational design of 3D/2D In2O3 nanocube/ZnIn2S4 nanosheet heterojunction photocatalyst with large-area "high-speed channels" for photocatalytic oxidation of 2,4-dichlorophenol under visible light

Abstract

We have rationally designed and fabricated of "face-to-face" 3D/2D In₂O₃ nanocube/ZnIn₂S₄ nanosheet heterojunction by growing ZnIn₂S₄ nanosheets on the surfaces of In₂O₃ cubes as photocatalysts for 2,4-dichlorophenol (2,4-DCP) degradation under visible light. Herein, the unique 3D/2D In₂O₃ nanocube/ZnIn₂S₄ nanosheet hierarchical structure not only exposes far more abundant heterojunction interface active sites compared to 3D/0D In₂O₃ nanocube/ZnIn₂S₄ nanoparticle, but also produces numbers of compact high-speed nanochannels in the junctions, which significantly promotes the separation and migration of photogenerated carriers. Profiting by structural and compositional advantages, the optimized 3D/2D ZnIn₂S₄-In₂O₃ photocatalyst shows excellent photocatalytic activity and stability in the degradation of 2,4-DCP, which is 1.85, 2.60, 3.02 and 3.54-fold higher than that of 3D/0D ZnIn₂S₄-In₂O₃, ZnIn₂S₄ nanosheet, ZnIn₂S₄ nanoparticle and In₂O₃, respectively. Meanwhile, the main active species (·O₂^-, ·OH and h⁺) produced in the photodegradation process were determined and the intermediates and degradation mechanism were studied in detail. Besides, the application on the removal of 2,4-DCP in natural water and actual wastewaters by 3D/2D ZnIn₂S₄-In₂O₃ also have been studied. This work provides a new strategy for efficiently optimize the advantages of binary nano-architectures to effectively degrade phenolic pollutants in the environment.

Keywords: 2,4-dichlorophenol; 3D/2D heterojunction; In(2)O(3) nanocube; Photocatalysis; ZnIn(2)S(4) nanosheet.