Identifying Active Sites of Pt-NiFe LDH Catalysts for CO Oxidation Using In-Situ DRIFTS with Multiple Microscopy and Spectroscopy Techniques

Layered double hydroxide (LDH) nanostructures are commonly used to study the interfacial effects of Pt-based catalysts in CO oxidation. However, the specific role and detailed intermediates involved in CO oxidation remain unclear. Density functional theory (DFT) predicted that NiFe LDH loaded with single Pt atoms would exhibit satisfactory CO oxidation activity. On this basis, we prepared Pt₁NiFe LDH catalysts with various Fe : Ni ratios by using the one-pot method and achieved favorable dispersion of single Pt atoms. Pt₁/FN-1, which had the optimal Fe : Ni ratio (1 : 1), exhibited satisfactory catalytic performance for CO oxidation and a high turnover frequency, as determined through DFT calculations and experimental characterization. In-situ diffuse reflectance infrared Fourier transform spectroscopy confirmed that CO directly reacted with Pt₁/FN-1 to produce CO₂ and that introduced O₂ formed bicarbonate species to produce CO₂ together with the adsorbed CO on Pt₁ sites. Overall, our work provides new insights into the catalytic mechanism of the well-known Pt₁NiFe LDH catalysts in CO oxidation.