Role of Ptnc-FeOx metal-oxide interface in enhancing the catalytic activity for CO oxidation

Abstract

BackgroundMetal-oxide interface plays critical roles in promoting the catalytic activities of metal catalysts in a vast diversity of reactions. Maximizing this interfacial interaction so as to optimize the catalytic performance is an active subject of research that is worthy of intensive exploration.PurposeThis study aims to develop new Pt-group catalysts that are highly active towards cryogenic CO catalytic oxidation, and explore effective strategies to engineer metal-oxide (hydroxide) interfaces to weaken the adsorption of CO and to enhance the adsorption/activation of O2.MethodsSupported ultrasmall Pt nanoclusters (Ptnc-FeOx/SiO2) of (1.4±0.2) nm were synthesized using deposition-precipitation with urea (DPU). The catalytic performance towards CO oxidation was examined by using a fixed-bed U-shape flow quartz reactor. Extended X-ray absorption fine structure (EXAFS), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and energy-dispersive X-ray spectroscopy (EDX) techniques were combined to study the Ptnc-FeOx interfacial interaction.ResultsThe Ptnc-FeOx/SiO2 catalyst shows superior catalytic performance than Pt/SiO2 towards the CO oxidation reaction. Kinetics tests show that both the apparent activation energy and turnover frequency of Ptnc-FeOx/SiO2 are greatly enhanced as compared with Pt/SiO2 (19 kJ·mol-1 vs. 64 kJ·mol-1; 0.044 s-1 vs. 0.002 s-1 at 37 °C).ConclusionThe charge transfer from Fe to Pt results in the downshifted d-band center of Pt and reduces the CO adsorption strength, and hence, playing important roles in promoting the catalytic activity of Pt catalysts.

Keywords

• metal-oxide interface
• ptnc-feox catalyst
• co catalytic oxidation
• xafs
• drifts