Construction of Z-scheme MnCo2O4/Sn3O4 heterostructured photoanodes with enhanced photoelectrocatalytic degradation of reactive brilliant blue KN-R

Abstract

Rapid and efficient handling of the printing and dyeing wastewater benefits environmental conservation. Photoelectrocatalysis (PEC) technology is a novel method used to mineralize large molecules of non-degradable organic dye molecules in water completely into small molecules in recent years. By generating intermediate reactive species (e.g., superoxide radicals and hydroxyl radicals) during the processing, the products of PEC technology are cleaner and pollution-free, making it a desirable environment-friendly approach. In this work, a composite semiconductor material with Z-Scheme heterostructure was constructed as a photoanode to promote the generation of intermediate reactive radicals for the efficient degradation of organic dyestuff wastewater. A series of composite materials with Sn3O4 nanosheets decorated spinel-type MnCo2O4 nanorods were synthesized through a simple two-step hydrothermal process on the titanium metal substrate. The degradation reaction cell was assembled with these Ti/MnCo2O4-Sn3O4 photoanodes, and the PEC approach was used to decolorize the reactive brilliant blue KN-R. The synthesized photoelectrode exhibited a large electroactive region, low charge transfer resistance, high hydroxyl radical generation efficiency, and excellent PEC activity. The optimal composite photoanode presented 86.4 % reactive brilliant blue KN-R removal in 2 h and practical stability in 5 circulation tests. The mechanism during the PEC process was also analyzed and discussed on the basis of radical trapping experiments. In this work, MnCo2O4-Sn3O4 materials possessing Z-scheme heterojunction were constructed, providing insight into the techniques for catalytic purification of organic wastewater.