Pt3Sn/C catalysts

Wang Q, Sun GQ, Jiang LH, Xin Q, Sun SG, Jiang YX, Chen SP, Jusys Z, Behm RJ (2007) Adsorption and oxidatimi of ethanol on colloid-based Pl/C, PtRn/C and Pt3Sn/C catalysts in situ FTIR spectroscopy and on-line DEMS studies. Phys Chem Chem Phys 9 2686-2696... 

Ir- and Rh-based catalysts [90-93] have been investigated for ethanol oxidation reaction, and there have been some interesting and reasonably promising results, de Tacconi et al. carried out in situ FTIR study on polycrystalline Ir and Rh electrodes and showed ethanol oxidation on Ir leading selectively to either acetic acid or acetaldehyde, while Rh is a better catalyst in the total oxidation of ethanol to CO2 [90]. Cao et al. studied carbon-supported lT3Sn nanoparticle electrocatalyst, and the fuel cell test results showed that the overall performance of IrsSn/C was comparable to that of the Pt3Sn/C catalyst [92]. 

After 15 min following the potential step to high potentials, the yields of CO2 are negligible for all four catalysts and all studied potentials. For Pt/C and PtRu/C catalysts, the yields of acetaldehyde and acetic acid are ca. 90% and 10%, respectively. In the case of Pt3Sn/C catalysts, the yield of acetaldehyde decreases to 80% and the yield of acetic acid increases to 20% at +0.6 V. A higher yield of acetic acid is observed on PtRh under potentiostatic conditions, similar to the results from potentiodynamic experiments. Also under potentiostatic, steady-state conditions, ethanol oxidation largely results in incomplete oxidation to byproducts (acetaldehyde and acetic acid), while complete oxidation to CO2 is only... 

Figure 11.7. Cyclic voltammograms of H2 oxidation in the presence of 2% CO on Pt/C (0.10 mg cm ), PtsoRuso/C (0.09 mg cm ), and Pt3Sn/C (0.12 mg cm ). T = 50 C scan rate = 50 mV s [22]. (Reprinted from Journal of Electroanalytical Chemistry, 528(1-2), Leng Y-J, Wang X, Hsing I-M, Assessment of CO-tolerance for different Pt-alloy anode catalysts in a polymer electrolyte fuel cell using ac impedance spectroscopy, 145-52, 2002, with permission from Elsevier.)...

In the case of PtSn catalysts, no evidence of a ligand effect was observed from an in situ FTIR study on Pt3Sn(l 10) bulk alloy and PtSn nanoparticles supported on carbon. It was proposed that the bifunctional mechaiusm was mainly involved in the oxidation process. The fact that the transition from positive to negative Stark shift of infrared v(CO) frequency during CO oxidation was much more pronoimced on a PtSn/C catalyst than on the Pt/C catalyst was interpreted in terms of the different ways in which OHads (necessary to oxidize CO) nucleates on each catalyst. 

Fig. 27 Steady-state total Faradaic currents (a), corresponding mass spectrometric currents of CO2 at m/z = 44 (b), and current efficiencies for CO2 formation (c) as a function of the reaction potential for the different catalyst electrodes. Black circles - Pt/C, black squares - PtRu/C, black triangles - Pt3Sn/C (E-TEK). Electrolyte flow rate 10 pL/s [881...

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