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Title: Synthesis and electrochemical characterization of Ti x Ta y Al z N 1-δ O γ for fuel cell catalyst supports

Authors:
; ;
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1398556
Grant/Contract Number:
SC0001086
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 246; Journal Issue: C; Related Information: CHORUS Timestamp: 2018-01-10 20:46:54; Journal ID: ISSN 0022-4596
Publisher:
Elsevier
Country of Publication:
United States
Language:
English

Citation Formats

Wakabayashi, Ryo H., Abruña, Héctor D., and DiSalvo, Francis J. Synthesis and electrochemical characterization of Ti x Ta y Al z N 1-δ O γ for fuel cell catalyst supports. United States: N. p., 2017. Web. doi:10.1016/j.jssc.2016.11.020.
Wakabayashi, Ryo H., Abruña, Héctor D., & DiSalvo, Francis J. Synthesis and electrochemical characterization of Ti x Ta y Al z N 1-δ O γ for fuel cell catalyst supports. United States. doi:10.1016/j.jssc.2016.11.020.
Wakabayashi, Ryo H., Abruña, Héctor D., and DiSalvo, Francis J. Wed . "Synthesis and electrochemical characterization of Ti x Ta y Al z N 1-δ O γ for fuel cell catalyst supports". United States. doi:10.1016/j.jssc.2016.11.020.
@article{osti_1398556,
title = {Synthesis and electrochemical characterization of Ti x Ta y Al z N 1-δ O γ for fuel cell catalyst supports},
author = {Wakabayashi, Ryo H. and Abruña, Héctor D. and DiSalvo, Francis J.},
abstractNote = {},
doi = {10.1016/j.jssc.2016.11.020},
journal = {Journal of Solid State Chemistry},
number = C,
volume = 246,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.jssc.2016.11.020

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  • Quinary Ti{sub x}Ta{sub y}Al{sub z}N{sub 1-δ}O{sub γ} of various compositions have been prepared by a co-precipitation method followed by ammonolysis. The nitride samples were examined as potential catalyst supports in polymer electrolyte membrane fuel cells. The nitride products crystallized in the rock salt (NaCl) structure over a wide range of compositions. The addition of Ta and Al was highly beneficial towards improving the chemical and electrochemical stability of TiN, without a significant loss of electrical conductivity. Platinum particles were successfully deposited on the (oxy)nitride samples, and the composite samples at some compositions were found to be comparable to Pt/carbon inmore » their stability and catalytic activity even without optimizing the Pt deposition and dispersion processes. - Graphical abstract: The effect of additions of Ta and Al into TiN structure. Shifts the lattice constant, and increases its chemical stability in acidic environment.« less
  • A new aluminum silicon oxycarbonitride, (Al{sub 5.8}Si{sub 1.2})(O{sub 1.0}C{sub 3.5}N{sub 1.5}), has been synthesized and characterized by X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and electron energy loss spectroscopy (EELS). The title compound is hexagonal with space group P6{sub 3}/mmc and unit-cell dimensions a=0.322508(4) nm, c=3.17193(4) nm and V=0.285717(6) nm{sup 3}. The atom ratios of Al:Si and those of O:C:N were, respectively, determined by EDX and EELS. The initial structural model was successfully derived from the XRPD data by the direct methods and further refined by the Rietveld method. The crystal is most probablymore » composed of four types of domains with nearly the same fraction, each of which is isotypic to Al{sub 7}C{sub 3}N{sub 3} with space group P6{sub 3}mc. The existence of another new oxycarbonitride (Al{sub 6.6}Si{sub 1.4})(O{sub 0.7}C{sub 4.3}N{sub 2.0}), which must be homeotypic to Al{sub 8}C{sub 3}N{sub 4}, has been also demonstrated by XRPD and TEM. - Graphical abstract: A new oxycarbonitride discovered in the Al-Si-O-C-N system, (Al{sub 7-x}Si{sub x})(O{sub y}C{sub z}N{sub 6-y-z}) (x{approx}1.2, y{approx}1.0 and z{approx}3.5). The crystal is composed of four types of domains (I, II, III and IV), and hence the structure is represented by a split-atom model. Individual crystal structures can be regarded as layered structures, which consist of A-type [(Al, Si){sub 4}(O, C, N){sub 4}] unit layers and B-type [(Al, Si)(O, C, N){sub 2}] single layers. Highlights: > (Al{sub 5.8}Si{sub 1.2})(O{sub 1.0}C{sub 3.5}N{sub 1.5}) as a new aluminum silicon oxycarbonitride. > Crystal structure is determined and represented by a split-atom model. > Existence of another new oxycarbonitride (Al{sub 6.6}Si{sub 1.4})(O{sub 0.7}C{sub 4.3}N{sub 2.0}) is demonstrated. > Both new materials are formed by oxidation and nitridation of (Al, Si){sub 6}(O, C){sub 5}.« less
  • Oxygen-deficient ferrates with the cubic perovskite structure Sr{sub x}Y{sub 1−x}FeO{sub 3−δ} were prepared in air (0.71≤x≤0.91) as well as in N{sub 2} (x=0.75 and 0.79) at 1573 K. The oxygen content of the compounds prepared in air increases with increasing strontium content from 3−δ=2.79(2) for x=0.75 to 3−δ=2.83(2) for x=0.91. Refinement of the crystal structure of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} using TOF neutron powder diffraction (NPD) data shows high anisotropic atomic displacement parameter (ADP) for the oxygen atom resulting from a substantial cation and anion disorder. Electron diffraction (ED) and high-resolution electron microscopy (HREM) studies of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79}more » reveal a modulation along 〈1 0 0〉{sub p} with G± ∼0.4〈1 0 0〉{sub p} indicating a local ordering of oxygen vacancies. Magnetic susceptibility measurements at 5–390 K show spin-glass behaviour with dominating antiferromagnetic coupling between the magnetic moments of Fe cations. Among the studied compositions, Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} shows the lowest thermal expansion coefficient (TEC) of 10.5 ppm/K in air at 298–673 K. At 773–1173 K TEC increases up to 17.2 ppm/K due to substantial reduction of oxygen content. The latter also results in a dramatic decrease of the electrical conductivity in air above 673 K. Partial substitution of Fe by Cr, Mn and Ni according to the formula Sr{sub 0.75}Y{sub 0.25}Fe{sub 1−y}M{sub y}O{sub 3−δ} (y=0.2, 0.33, 0.5) leads to cubic perovskites for all substituents with y=0.2. Their TECs are higher in comparison with un-doped Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79}. Only M=Ni has increased electrical conductivity compared to un-doped Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79}. - Graphical abstract: Oxygen-deficient ferrates with the cubic perovskite structure Sr{sub x}Y{sub 1−x}FeO{sub 3−δ} were prepared both in air (0.71≤x≤0.91) and N{sub 2} (x=0.75 and 0.79) at 1573 K. Refinement of the crystal structure of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} using TOF neutron powder diffraction (NPD) data (S.G. Pm-3m, a=3.86455(3) Å; χ{sup 2}=6.71, R{sub p}=0.03; R{sub wp}=0.04) confirmed the cubic perovskite structure. The observed high anisotropic atomic displacement parameter for the oxygen atom indicates a substantial anion sublattice disorder. Electron diffraction (ED) and high-resolution electron microscopy (HREM) studies of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} show compositional modulation along 〈1 0 0〉{sub p} with G± ∼0.4〈1 0 0〉{sub p} indicating ordering of oxygen vacancies at the local scale. Highlights: ► Cubic perovskites Sr{sub x}Y{sub 1−x}FeO{sub 3−δ} (0.71≤x<0.91) were synthesized. ► Sr{sub 0.75}Y{sub 0.25}Fe{sub 1−y}M{sub y}O{sub 3−δ}, M=Cr, Mn, Ni were prepared. ► High-temperature conductivity properties and crystal structure were studied. ► High-temperature thermal expansion behavior was investigated.« less
  • Synthetic hollandite compounds of composition Ba/sub x/M(IV)/sub 4-2x/N(III)/sub 2x/O/sub 8/ (M=Ti, Ge, Ru, Zr, Sn; N=Al, Sc, Cr, Ga, Ru, In) and Sr/sub x/M(IV)/sub 4-2x/N(III)/sub 2x/O/sub 8/ (M=Ti, Ge, Ru; N=Al, Cr, Ga) and (A, Ba)/sub x/Ti/sub y/Al/sub z/O/sub 8/ with A=Rb, Cs, Ca, Sr have been studied by electron and X-ray diffraction and high resolution electron microscopy. They have been found to be stable only within certain ranges of x, depending on the M and N ions. The lower value of x is never less than 0.56, the upper x level is about 0.73. Higher x are correlated withmore » larger radii of M and N. The variation in x gives rise to an incommensurate occupation by the A ions in the tunnels. Correlation among tunnel sequences varies widely, also depending on the nature of the M and N ions. The lower and upper x, the cell dimensions, the correlation between the tunnels and the stability in water at 300/sup 0/C of the existing hollandites are given.« less