CHEMICAL SCIENCE

Research on the regulation and application of catalytic performance of nano-heterostructures has progressed


Recently, Yang Rong’s research group of the National Center for Nanoscience of the Chinese Academy of Sciences has made progress in the regulation and application of catalytic performance of nano-heterostructures. The research results were published in the Journal of Chemical Engineering (Chemical) under the title Synergistic Degradation of Tetracycline from Mo2C/MoOx Films Mediated Peroxymonosulfate Activation and Visible-light Triggered Photocatalysis Engineering Journal).

Photocatalysis and persulfate oxidation are currently research hotspots in the field of advanced oxidation technology. The photocatalytic reaction uses semiconductor materials as catalysts, but photogenerated electrons and holes in a single material are easy to recompose, which limits the photocatalytic ability of the materials. Persulfate oxidation uses persulfate to produce free radicals with strong oxidizing ability to degrade pollutants or inactivate bacteria. Although cobalt/ferrous ions can be used as catalysts to activate Peroxymonosulfate (PMS) to produce strong oxidizing sulfate radicals (SO4·-), metal ions are difficult to recover and may cause secondary pollution.

Yang Rong’s research group prepared a molybdenum-based nano-heterostructure (Mo2C/MoOx) in situ on carbon cloth by chemical vapor deposition, and used it to construct a new photocatalytic/PMS oxidation coupling system, and studied the catalytic performance of molybdenum-based photocatalytic/PMS/visible light composite system in the degradation of antibiotics. Using tetracycline (TC) as a model, this study explored the effects of different component content, PMS dosage, initial pH, TC concentration, temperature, coexistence anion, and illumination time on the performance of the system. In this work, the possible reaction mechanism was analyzed, and a catalytic reaction system for photocatalysis/PMS activation of nano-heterostructures was constructed, which realized efficient degradation of antibiotics.

Mo2C/MoOx materials with different band structures of molybdenum-based components form Z-scheme heterojunctions, which reduces the recombination efficiency of electrons and holes, while retaining the high redox ability of electrons and holes, which is conducive to the improvement of the photocatalytic performance of the materials. The polyvalent molybdenum ions in the heterojunction promoted electron transfer during PMS activation and further generated more active free radicals. The capture of electrons by PMS can improve the separation efficiency of electrons and holes in the photocatalytic process, thereby improving the photocatalytic efficiency.

The outstanding advantages of this strategy are: molybdenum-based components with different band structures are formed in one step in the nano-heterostructure, which simplifies the construction process of heterojunctions; The material has full-spectrum absorption characteristics, abundant molybdenum sites, and activates PMS to synergically and efficiently degrade antibiotics under visible light drive. The nano-heterostructures synthesized in situ on the carbon cloth substrate are easy to recover from the reaction solution, avoiding secondary pollution to the water body. The material can still maintain a high catalytic capacity after 10 cycles.

The novel molybdenum-based nano-heterostructure photocatalytic/PMS oxidation coupling system provides an effective regulatory strategy to break through the activity-stability trade-off limitation of heterogeneous catalysts in advanced oxidation systems. At the same time, the preparation method is simple, the catalytic performance is high, the repeatability and separation performance are good, which is conducive to promotion, and provides technical support for further promoting the practical application of nanomaterials and photocatalytic/persulfate advanced oxidation treatment technology.

The research work is supported by the strategic leading science and technology project of the Chinese Academy of Sciences and the national key research and development plan. (Source: National Center for Nanoscience, Chinese Academy of Sciences)

Figure 1. Molybdenum-based nano-heterostructure (Mo2C/MoOx)

Figure 2. Novel molybdenum-based nano-heterojunction photocatalytic/PMS oxidation coupling system

Related paper information:https://doi.org/10.1016/j.cej.2023.143774

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