Interfacial electron redistribution in 2D/3D MoS2/CuBi2O4 p-n heterojunction for visible light assisted reduction of Cr(VI) and oxidation of antibiotics

Abstract

We report the successful design of a heterojunction comprising p-type CuBi2O4 (CBO) and n-type MoS2 semiconductors. This was achieved through a hydrothermal and calcination method, resulting in the uniform deposition of three-dimensional CBO nano-cubes onto the surface of two-dimensional MoS2 nanosheets. Under visible light, the best MoS2/CBO composite exhibited the maximum catalytic efficacy for both the reduction of Cr (VI) and the oxidation of tetracycline hydrochloride (TC) at a molar ratio of 10:1. For tetracycline degradation the heterostructure achieved 83 % efficiency and a rate constant of 0.00412 min-1 after 180 min, while complete reduction of Cr(VI) was achieved, with a rate constant of 0.11 min-1 after 40 min. The efficiency of MoS2/CBO was averagely 1.4 times higher than that of the pristine materials for TCE degradation, while the activity was almost 1.8 times of the pristine materials for Cr(VI) reduction. The remarkable catalytic activity can be ascribed to the combined effects of electron redistribution and charge transfer between 2D MoS2 and 3D CuBi2O4 leading to the formation of a heterostructure and thereby facilitating strong interfacial interactions among the components causing effective absorption of visible light and improved separation of photogenerated electron-hole pairs. It is important to note that MoS2/CBO demonstrated excellent stability and reusability after 6 cycles. The primary reactive species responsible for TC degradation were identified as photo-generated h+, and •O2- . Additionally, e- was found to be mainly liable for Cr (VI) photoreduction. Furthermore, we propose a plausible photocatalytic reaction pathway for the elimination of both TC and Cr(VI). This research provides valuable inroads into the development of heterojunction photocatalysts for efficient water de-toxification.