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Nitrogen and carbon doped titanium oxide as an alternative and ultra-stable support to platinum catalysts is prepared and its efficiency is determined by polymer electrolyte fuel cell. Nitrogen and carbon doped titanium oxide is prepared by varying the melamine ratio followed by calcination at 900 °C. Platinum nanoparticles are deposited onto doped and undoped titanium oxide by colloidal method. The doping effect, surface morphology, chemical oxidation state and metal/metal oxide interfacial contact are studied by X-ray diffraction, Raman spectroscopy, high resolution transmission electron microscopy and X-ray photo electron spectroscopy. The nitrogen and carbon doping changes both electronic and structural properties of titanium oxide resulting in enhanced oxygen reduction reaction activity. The platinum deposited on optimum level of nitrogen and carbon doped titanium oxide exhibits improved cell performance in relation to platinum on titanium oxide electrocatalysts. The effect of metal loading on cathode electrocatalyst is investigated by steady-state cell polarization. Accelerated durability test over 50,000 cycles for these electrocatalysts suggested the improved interaction between platinum and nitrogen and carbon doped titanium oxide, retaining the electrochemical surface area and oxygen reduction performance as comparable to platinum on carbon support. [ABSTRACT FROM AUTHOR]

Abstract: Oxygen reduction reaction (ORR) is one of the most interesting research issues in the academia and industries due to its importance in polymer electrolyte membrane fuel cells. Development of new ORR catalysts with low cost and high activity is under intensive research, but it is a time-consuming process because of wide range of alloys to be explored. Combinatorial synthesis and high-throughput screening techniques were suggested as new experimental approaches to accelerate the ORR electrocatalyst research. The combinatorial method is focused on the synthesis of concentrated arrays and quick evaluation of the arrays via various screening techniques. In this report, the combinatorial approaches for the ORR catalyst research were reviewed based on the screening methods. Four screening techniques of optical screening, scanning electrochemical microscopy, multielectrode half cell, and multielectrode full cell were introduced as the representative ones. Other approaches were also briefly introduced. Merits and limitations of each method were discussed and representative research results of each method were shown in detail. [Copyright &y& Elsevier]

Abstract: Carbon supported Pt3Y (Pt3Y/C) and PtY (PtY/C) were investigated as oxygen reduction reaction (ORR) catalysts. After synthesis via reduction by NaBH4, the alloy catalysts exhibited 10–20% higher mass activity (mAmgPt −1) than comparably synthesized Pt/C catalyst. The specific activity (μAcmPt −2) was 23 and 65% higher for the Pt3Y/C and PtY/C catalysts, respectively, compared to Pt/C. After annealing at 900°C under a reducing atmosphere, Pt3Y/C-900 and PtY/C-900 catalysts showed improved ORR activity; the Pt/C and Pt/C-900 (Pt/C catalyst annealed at 900°C) catalysts exhibited specific activities of 334 and 393μAcmPt −2, respectively, while those of the Pt3Y/C-900 and PtY/C-900 catalysts were 492 and 1050μAcmPt −2, respectively. X-ray diffraction results revealed that both the Pt3Y/C and PtY/C catalysts have a fcc Pt structure with slight Y doping. After annealing, XRD showed that more Y was incorporated into the Pt structure in the Pt3Y/C-900 catalyst, while the PtY/C-900 catalyst remained unchanged. Although these results suggested that the high ORR activity of the PtY/C-900 catalyst did not originate from Pt–Y alloy formation, it is clear that the Pt–Y system is a promising ORR catalyst which merits further investigation. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a novel catalyst is prepared by dispersing planar polyphthalocyanine cobalt (PPcCo) synthesized by polymerizing cobalt (II)-4, 4′,4″,4‴-phthalocyanine tetracarboxylic acid (TcPcCo) using a high surface area carbon powder (Vulcan XC 72), and then heat-treated in argon (Ar) atmosphere. The polymer and PPcCo/C catalysts are characterized systematically by a variety of methods, such as ultraviolet–visible (UV–vis) spectrophotometer, Fourier transform infrared spectrometer (FT-IR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscope (TEM). Results show that the PPcCo obtained is stable below 600°C. The active site of PPcCo/C is CoN4 in phthalocyanine ring, and the PPcCo is dispersed homogeneously on the surface of XC 72. Electrocatalytic properties and electrochemical stability of the catalysts in 0.5molL−1 H2SO4 are evaluated by RDE measurements. The initial potential for O2 reduction in O2-saturated H2SO4 is 0.81V and it catalyzed O2 reduction mainly through a four-electron process. Almost no performance degradation is observed over continuous cyclic voltammetry (CV) at 10,000 cycles (4 days). Polarization curves obtained by linear sweep voltammetry (LSV) at 200 cycles also show no change. PPcCo/C catalysts display significant electrocatalytic performance for O2 reduction, tolerance towards methanol, and long-term stability. [Copyright &y& Elsevier]