Photocatalytic preparation of nanostructured MnO2-(Co3O4)/TiO2 hybrids: The formation mechanism and catalytic application in SCR deNOx reaction

Photocatalysis has already triggered enormous researches in the areas of solar energy transfer, environmental purification, organic synthesis and etc. In this work, the photocatalytic reactions were applied to controllably prepare nanostructured MnO2-(Co3O4)/TiO2 hybrids with highly distributed active components. The loading of flocculent MnO2 over TiO2 nanorods was rapidly achieved through the redox reactions between the MnO4- and photoexcited electrons. Three steps were involved in the formation of MnO2-Co3O4 hybrids, namely the oxidation of Co2+ to Co3+ by the photogenerated holes, the deposition of intermediate CoOOH over MnO2 and finally the decomposition of CoOOH by calcination to form Co3O4. Selective catalytic reduction of NO with NH3 (NH3-SCR) has been chosen as a model reaction to explore its application. It was found out that the unique MnO2-(Co3O4)/TiO2 hybrids exhibited promoted low temperature performance compared to that of prepared via impregnation, which was attributed to the abundant MnO2 species, surface active oxygen, surface Ti3+ species and acid sites. We believe the MnO2-(Co3O4)/TiO2 hybrids were also interested in other applications of environmental catalysis. (C) 2016 Elsevier B.V. All rights reserved.