Two-dimensional (2D) layered heterojunctions with a staggered band structure and unique interface properties exhibit promising application prospects in photocatalytic pollutant removal, water splitting, and CO2 reduction. Ultrathin 2D/2D heterojunctions with a large specific surface area and a short migration path of the photogenerated charge always illustrate a better photocatalytic performance than non-ultrathin 2D heterojunction photocatalysts. In this study, a novel ultrathin 2D/2D heterojunction of the Bi2O2(OH)(NO3)/BiOBr nanosheet composite (ultrathin BION/BiOBr) was in situ self-assembled though a cetyltrimethylammonium bromide assisted one-step hydrothermal method. Benefiting from the advantage of the unique ultrathin heterojunction structure, the ultrathin 2D/2D BION/BiOBr heterojunctions exhibit a greatly improved photocatalytic removal effect for multiple pollutants compared to the nanocrystal BION/BiOBr, pure BION. As a representative, the ultrathin 2D/2D Br-modified BION/BiOBr heterojunction shows an enhanced tetracycline degradation rate of 76%, which corresponded to a higher photodegradation rate constant of 0.01116 min-1 when compared to pure BION (17%, 0.00161 min-1) and nanocrystal BION/BiOBr (24%, 0.00223 min-1) under visible-light irradiation for 2 h. A series of characterization and density functional theory calculations demonstrate the enhanced separation and migration efficiency of the photogenerated electrons and holes over the ultrathin heterojunction, facilitating the formation of oxidizing groups for the organic pollutant removal. The possible mechanism of the TC photodegradation and the possible photodegradation pathway are also investigated in detail. This work provides a feasible method for constructing ultrathin 2D/2D heterojunction materials for environmental purification.
Keywords: Bi(2)O(2)(OH)(NO(3)); BiOBr; Environmental purification; Photocatalysis; Ultrathin heterojunction.
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