Ozone elimination over oxygen-deficient MnOx based catalysts: Effect of different transition metal dopants

Abstract

Ozone pollutant can be decomposed by catalysts at room temperature. In this study, pristine β-MnO2 and those doped with Co, Cu, and Ce were synthesized by a redox precipitation method. Their catalytic performance on ozone decomposition was further investigated at room temperature under both dry and humid (RH = 35%) gas conditions. Our results showed that Co and Cu doped MnO2 catalysts, especially the Co doped one, could enhance the room-temperature decomposition activity and improve the stability of catalyst. But Ce doped MnO2 catalyst exhibited lower ozone decomposition activity even than the pristine MnO2. To reveal their intrinsic promotion and inhibition mechanisms, those catalysts were characterized with XRD, N2 physisorption, TEM, SEM, XPS, Raman, H2-TPR, and O2-TPD. The introduction of dopants in MnO2 catalysts resulted in higher surface specific area and lower crystallinity than their pristine counterpart. Those dopants also helped tailor the number and type of the oxygen vacancies on the surface of catalysts. The appearance of isolated CeO2 in Ce doped MnO2, though have more oxygen vacancies, hindered the desorption of oxygen intermediates owing to their different nature of oxygen vacancies when compared to those Co or Cu doped catalysts.