Electronic Metal-Support Interactions between Pt Nanoparticles and Co(OH)2 Flakes for CO Oxidation

Electronic metal-support interactions (EMSIs) have opened a new way to tailor the electronic and catalytic properties of supported catalysts. Herein, we demonstrate the EMSIs between Pt nanoparticles and Co(OH)(2) flakes grown on SiO2 and show its beneficial effect on enhancing the CO oxidation activity. The EMSI characteristics of the Pt-Co(OH)(2)/SiO2 catalyst are identified by in situ X-ray absorption fine structure (XAFS) spectroscopy, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and transmission electron microscopy. Quantitative XAFS analysis reveals the presence of metallic-like Pt-Co bonds. The formation of Pt-Co intermetallic bonds allows for electron donation form Co to Pt, leading to the negative charging of the Pt atoms as evidenced by reduced Pt 2p-to-Sd electron-transition intensity detected by XAFS spectroscopy and the emergence of a CO adsorption band at 2063 cm(-1) in DRIFTS. The significance of EMSIs is manifested by comparing the CO oxidation activity over the Pt-Co(OH)(2)/SiO2 and Pt/SiO2 catalysts with similar Pt loadings. Pt-Co(OH)(2)/SiO2 is superior to Pt/SiO2 in both the apparent activation energy (19 vs 64 kJ/mol) and the turnover frequency (0.03 vs 0.003 s(-1) at 37 degrees C). The enhanced activity is attributed to the negative charging of Pt, which downshifts the d-band center and reduces the CO adsorption strength.