Nanostructure and formation mechanism of Pt-WO₃/C nanocatalyst by ethylene glycol method

Abstract

Pt-WO₃ nanoparticles uniformly dispersed on Vulcan XC-72R carbon black were prepared by an ethylene glycol method. The morphology, composition, nanostructure, electrochemical characteristics and electrocatalytic activity were characterized, and the formation mechanism was investigated. The average particle size was 2.3 nm, the same as that of Pt/C catalyst. The W/Pt atomic ratio was 1/20, much lower than the design of 1/3. The deposition of WO₃·xH₂O nanoparticles on Vulcan XC-72R carbon black was found to be very difficult by TEM. From XPS and XRD, the Pt nanoparticles were formed in the colloidal solution of Na₂WO₄, the EG insoluble Na₂WO₄ resulted in the decreased relative crystallinity and increased crystalline lattice constant compared with those of Pt/C catalyst and, subsequently, the higher specific electrocatalytic activity as determined by CV. The Pt-mass and Pt-electrochemically-active-specific-surface-area based anodic peak current densities for ethanol oxidation were 422.2 mA·mg⁻¹Pt and 0.43 mA·cm⁻²Pt, 1.2 and 1.1 times higher than those of Pt/C catalyst, respectively.

Keywords

Pt-based catalyst / tungsten oxide / ethylene glycol method / fuel cell

References

[1] Vigier F., Coutanceau C., Perrard A., . Development of Anode Catalysts for a Direct Ethanol Fuel Cell[J]. J. Appl. Electrochem., 2004, 34(4): 439-446.

[2] Song S. Q., Zhou W. J., Liang Z. X., . The Effect of Methanol and Ethanol Cross-over on the Performance of PtRu/C-based Anode DAFCs[J]. Appl. Catal. B, 2005, 55(1): 65-72.

[3] Song S. Q., Tsiakaras P. Recent Progress in Direct Ethanol Proton Exchange Membrane Fuel Cells (DE-PEMFCs) [J]. Appl. Catal. B, 2006, 63(3–4): 187-193.

[4] Ghumman A., Pickup P. G. Efficient Electrochemical Oxidation of Ethanol to Carbon Dioxide in a Fuel Cell at Ambient Temperature[J]. J. Power Sources, 2008, 179(1): 280-285.

[5] Götz M., Wendt H. Binary and Ternary Anode Catalyst Formulations Including the Elements W, Sn and Mo for PEMFCs Operated on Mmethanol or Reformate Gas[J]. Electrochim. Acta, 1998, 43(24): 3 637-3 644.

[6] Roth C., Götz M., Fuess H. Synthesis and Characterization of Carbon-supported Pt-Ru-WOx Catalysts by Spectroscopic and Diffraction Methods[J]. J. Appl. Electrochem., 2001, 31(7): 793-798.

[7] Jayaraman S., Jaramillo T. F., Baeck S. H., . Synthesis and Characterization of Pt-WO₃ as Methanol Catalysts for Fuel Cells[J]. J. Phys. Chem. B, 2005, 109(48): 22 958-22 966.

[8] Ganesan R., Lee J. S. An Electrocatalyst for Methanol Oxidation Based on Tungsten Oxide Microspheres and Platinum[J]. J. Power Sources, 2006, 157(1): 217-221.

[9] Rajesh B., Karthik V., Karthikeyan S., . Pt-WO₃ Supported on Carbon Nanotubes as Possible Anodes for Direct Methanol Fuel Cells[J]. Fuel, 2002, 81(17): 2 177-2 190.

[10] Rajesh B., Ravindranathan T. K. Carbon Nanotubes Generated from Template Carbonization of Polyphenyl Acetylene as the Supported for Electrooxidation of Methanol[J]. J. Phys. Chem. B, 2003, 107(12): 2 701-2 708.

[11] S Tanaka, M Umeda, H Ojima, et al. Preparation and Evaluation of a Multi-component Catalyst by Using a Co-sputtering System for Anodic Oxidation of Ethanol[J]. J. Power Sources, 152(1): 34–39

[12] Liao S. J., Linkov V., Petrik L. Anodic Oxidation of Ethanol on Inorganic Membrane-based Electrodes[J]. Appl. Catal. A, 2004, 258(2): 183-188.

[13] Pereira L. G. S., Santos F. R., Pereira M. E., . CO Tolerance Effects of Tungsten-based PEMFC Anodes[J]. Electrochim. Acta, 2006, 51(19): 4 061-4 066.

[14] Maillard F., Peyrelade E., Soldo O. Y., . Is Carbon-supported Pt-WOx Composite a CO-tolerant Material? [J]. Electrochim. Acta, 2007, 52(5): 1 958-1 967.

[15] Zhou W. J., Li W. Z., Song S. Q., . Bi- and Tri-metallic Pt-based Anode Catalysts for Direct Ethanol Fuel Cells[J]. J. Power Sources, 2004, 131(1–2): 217-223.

[16] Tseung A. C. C., Chen K. Y. Hydrogen Spill-over Effect on Pt/WO₃ Anode Catalysts[J]. Catal. Today, 1997, 38(4): 439-443.

[17] Park K. W., Ahn K. S., Nah Y. C., . Electrocatalytic Enhancement of Methanol Oxidation at Pt-WO₃ Nanophase Electrodes and In-situ Observation of Hydrogen Spillover Using Electrochromism[J]. J. Phys. Chem. B, 2003, 107(18): 4 352-4 355.

[18] Roth C., Götz M., Fuess H. Synthesis and Characterization of Carbon-supported Pt-Ru-WOx Catalysts by Spectroscopic and Diffraction Methods[J]. J. Appl. Electrochem., 2001, 31(7): 793-798.

[19] Yang L. X., Bock C., MacDougall B. The Role of the WOx Adcomponent to Pt and PtRu Catalysts in the Electrochemical CH₃OH Oxidation Reaction[J]. J. Appl. Electrochem., 2004, 34(4): 427-438.

[20] Tsang K. Y., Lee T. T., Ren J. W., . Platinum Tungsten Oxide (Pt-WO₃) Nanoparticles: Their Preparation in Glycol and Electrocatalytic Properties[J]. J. Exp. Nanosci., 2006, 1(1): 113-123.

[21] Hull R. V., Li L., Xing Y. C., . Pt Nanoparticle Binding on Functionalized Multiwalled Carbon Nanotubes[J]. Chem. Mater., 2006, 18(7): 1 780-1 788.

[22] Johansson G., Hedman J., Berndtsson A., . Calibration of Electron Spectra[J]. J. Electron. Spectrosc. Relat. Phenom., 1973, 2(3): 295-317.

[23] Drawdy J. E., Hoflund G. B., Gardner S. D., . Effect of Pretreatment on a Platinized Tin Oxide Catalyst Used for Lowtemperature CO Oxidation[J]. Surf. Interface Anal., 1990, 16(1–12): 369-374.

[24] Bancroft G. M., Adams L., Coatsworth L. L., . ESCA Study of Sputtered Platinum Films[J]. Anal. Chem., 1975, 47(3): 586-588.

[25] Ho S. F., Contarini S., Rabalais J. W. Ion-beam-induced Chemical Changes in the Oxyanions (Moyn-) and Oxides (Mox) Where M=Chromium, Molybdenum, Tungsten, Vanadium, Niobium and Tantalum[J]. J. Phys. Chem., 1987, 91(18): 4 779-4 788.

[26] Ma G. X., Tang Y. W., Yang H., . Electrocatalytic Activity of Pt/C Catalyst Prepared with Solid Phase Reaction Method for Ethanol Oxidation (in Chinese) [J]. Acta Phys. Chim. Sin. (Wuli Huaxue Xuebao), 2003, 19(11): 1 001-1 004.

[27] Liao S. J., Chen M. Factors to Affect Preparation of Pt/C Catalyst via Organic Colloidal Method (in Chinese) [J]. J. S. China Univ. Technol. (Nat. Sci. Edition.), 2008, 36(11): 1-6.

[28] Kulesza P. J., Faulkner L. R. Electrodeposition and Characterization of Three-dimensional Tungsten (VI, V)-oxides Films Containing Spherical Pt Microspheres[J]. J. Electrochem. Soc., 1989, 136(3): 707-713.

[29] Shim J., Lee C. R., Lee H. K., . Electrochemical Characteristics of Pt-WO₃/C and Pt-TiO2/C Electrocatalysts in a Polymer Eelectrolyte Fuel Cell[J]. J. Power Sources, 2001, 102(1–2): 172-177.

[30] Green C. L., Kucernak A. Determination of the Platinum and Ruthenium Surface Areas in Platinum-ruthenium Alloy Electrocatalysts by Underpotential Deposition of Copper. I. Unsupported Catalysts[J]. J. Phys. Chem. B, 2002, 106(5): 1 036-1 047.

[31] Zhou W. J. Research on the Anode Catalysts for Low-temperature Direct Alcohol Fuel Cells[D], 2003 Dalian Dalian Inst. Chem. Phys., Chinese Acad. Sci.

[32] Zhang X. J., Lu S. G., Li W. Z. Preparation and Characterization of H₂Pt(OH)₆ (in Chinese) [J]. Chinese J. Rare Metals, 2005, 29(3): 307-310.

[33] Helena Nogueira I. S., Cavaleiro Ana M. V., Rocha J., . Synthesis and Characterization of Tungsten Trioxide Powders Prepared From Tungstic Acids[J]. Mater. Res. Bull., 2004, 39(4–5): 683-693.

[34] Hu S., Zhu Z. L., Luo S. Z., . Preparation Methods of Pt/C Catalysts for Hydrophobic Pt/C/PTFE Catalysts [J]. Chem. Bull., 2006, 69(12): 1-6.

[35] LGS Software Studio. Chemhandbook 3.0 [DB/OL], 2007 Beijing Chem. Ind. Press