CoO QDs/Bi2MoO6 monolayer: A novel S-scheme heterojunction for highly efficient photocatalytic C2H4 degradation

As a plant hormone, C2H4 causes significant economic losses during the storage and transportation of fruits and vegetables. How to efficiently photocatalytic oxidation of atmospheric C2H4 using sun-light remains a significant challenge at the frontiers of chemistry. Inspired by natural photosynthesis of plant, here, we design a novel S-scheme heterojunction for highly efficient photocatalytic C2H4 degradation. We first conducted density functional theory (DFT) calculations to predict an S-scheme heterojunction can be formed between CoO and Bi2MoO6, and then fabricated a novel CoO Quantum dots (QDs)/Bi2MoO6 monolayer S-scheme heterojunction by using a practical hydrothermal approach to in-situ deposit CoO QDs on a Bi2MoO6 monolayer. Furthermore, the UV–Vis DRS, UPS, in-situ XPS and electron spin resonance (ESR) characterization of DMPO-•O2– signals and DMPO-•OH signals evidence that the transfer pathway of space charge in photocatalytic degradation of ethylene accords with the S-scheme. Moreover, due to the unique structural design, CoO QDs and Bi2MoO6 monolayer form an S-scheme heterojunction, and the intimate contact that enables efficient charge transfer and sufficient redox ability simultaneously, the CoO QDs/Bi2MoO6 monolayer catalyst achieves a remarkable ethylene photocatalytic-degradation rate of 3.27 × 10−2∙min−1, 19.2 times higher than CoO and 22.5 times higher than Bi2MoO6. This work provides novel insights for designing efficient S-scheme photocatalysts for C2H4 degradation.