1School of Energy Science and Technology, University of Electronic Science and Technology of China, Chengdu, 611731, China
2Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
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DOI:
10.7502/j.issn.1674-3962.2015.04.02
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Abstract:
Previous Experiments reported that precious-metal Pt is able to migrate between perovskite CaTiO3 surface and bulk with change of the external redox conditions. This novel process can efficiently suppress the agglomeration of precious-metal particles, and maintain the high performance of the so-called “intelligent catalysts” for a long period. However, the study of the interactions between precious-metal and CaTiO3 substrate is rather limited. The first-principles calculations combined with cluster expansion and Monte Carlo methods were employed to construct the PtOx-CaO-TiOx pseudo-ternary phase diagrams to explore the properties of Pt-doped CaTiO3 system. The first-principles phase diagrams show that Pt can be doped in CaTiO3 and occupy the Ti-site at various concentrations, and the thermodynamic phase diagrams indicate that the doped CaTi1-xPtxO3 structures evolve to solid solutions at ambient temperatures. More importantly, Pt tends to dissolve into CaTiO3 substrate under oxidizing conditions while precipitate from the perovskite matrix and exist as metallic particles under reducing conditions, which is consistent with the concept of “intelligent catalyst”. Furthermore, the investigations of the phase diagram indicate the existence of some other oxides and metal alloys in the catalyst system at various conditions. The results might inform the experiments and be helpful for preparing highly efficient catalysts for elimination of harmful exhaust gas.