Construction of ultrafine and stable PtFe nano-alloy with ultra-low Pt loading for complete removal of CO in PROX at room temperature

• Very active and stable PtFe with ultra-low Pt for PROX was designed and prepared.
• The structure of the as-prepared PtFe was characterized to be PtFe nano-alloy.
• Its excellent performance was originated from the higher Pt utilization.
• The active site for O2 activation is ferrous iron not ferric oxide.
• The PtFe catalyst can be stabilized by supporting on TiO2.

Rational design of highly effective catalysts based on the understanding of structure–activity relationship is becoming more and more important in heterogeneous catalysis. In this study, we have designed and successfully prepared a highly active PtFe nano-alloy catalysts with ultra-low Pt loading for the preferential oxidation of CO, over which CO can be completely removed at room temperature. As compared to the previously reported Pt@Fe quasi-core–shell catalysts with similar performance, the Pt loading of the as-prepared PtFe/Al2O3 nano-alloy catalysts can be decreased by a factor of 6 due to the increased Pt utilization. Based on in situ diffuse reflectance infrared spectroscopy (DRIFTS) and quasi-in situ XPS, it can be concluded that O2 is activated over ferrous iron on the PtFe/Al2O3 nano-alloy catalysts, leading to the high performance towards preferential oxidation of CO. Under reaction conditions, the active species will be oxidized to ferric oxide, thus O2 activation ability and catalytic activity decrease. Based on the above understanding, we further constructed a highly stable catalyst by supporting PtFe nano-alloy particles onto TiO2, which can help to activate O2 and stabilize the lower valence Fe species.

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