Facile preparation of a novel core-shell fiber S-scheme C/CoS2@BiOBr heterojunction photocatalyst for efficient degradation of Congo red under visible light

Abstract

Generally, it is of great scientific significance to improve the utilization of solar energy resources. However, it is still a huge challenge at present. For this reason, the construction of photocatalysts with heterostructures is an effective way. In this paper, a novel core-shell fiber-like C/CoS2@BiOBr S-scheme heterojunction with visible light response was rationally designed by in-situ reduction of MOF through anion exchange strategy. Density functional theory (DFT) calculation and characterization analysis show that the internal electric field is formed between C/CoS2 and BiOBr after contact. This is beneficial to charge transfer and separation, and the S-sheme transfer path endows the separated electrons and holes with large redox potential to participate in the reaction directly. Moreover, the addition of BiOBr significantly enhanced the visible light absorption of the composites and improved the photochemical properties. It is worth noting that C/CoS2@BiOBr has excellent catalytic ability, and the optimal value of photodegradation of Congo red (CR) reaches more than 99 % within 15 min of visible light irradiation. Consequently, the active species were •O2- and h+. •O2- play a dominant role in the photocatalytic process. The space charge transfer and possible separation mechanisms of the new heterostructures are further proposed. This study provides some new ideas for the preparation of efficient water purification photocatalysts.