XRD and electrochemical investigation of particle size effects in platinum-cobalt cathode electrocatalysts for oxygen reduction

Abstract

International audiencePt-Co/C electrocatalysts with Pt loadings near 30 wt. % prepared by the impregnation method in water - ethylene glycol solutions were investigated by X-ray diffraction and correlated with electrochemical measurements. We show that the composition of the binary solvent controls the average particle size and its distribution. The unit cell parameter of the Pt3Co alloy decreases nonlinearly with decreasing particle size. The ORR activity of the prepared Pt-Co/C catalysts in H2SO4 solution enhances with decreasing particle size and unit cell parameter as well as with narrowing of the particle size distribution. Corrosion treatment of the synthesized Pt-Co/C materials causes an increase of ca. 1 nm in average particles size accompanied by broadening of the particle size distribution and decreasing Co content in the Pt-Co alloy. All of the synthesized Pt-Co/C materials show higher ORR activities than do the commercial Pt/C electrocatalysts

Effect of milling parameters on the formation of nanocrystalline hydroxyapatite using different raw materials

“…In this paper, full width at half maximum (FWHM) of specified peaks was utilized to determine the fraction of crystalline phase. may be ascribed to the three factors: the presence of stacking faults, the presence of dislocations and nonequivalence of the grain sizes along different crystallographic directions [33]. In our case, it seems that this phenomenon is due to the grain size anisotropy.…”

A comparative study of hydroxyapatite nanostructures produced under different milling conditions and thermal treatment of bovine bone

“…Examination of the FWHM values for all the samples revealed the occurrence of anisotropic line broadening. In general, the anisotropic line broadening may be ascribed to the three factors: the presence of stacking faults, the presence of dislocations and nonequivalence of the grain sizes along different crystallographic directions [38]. In our case, it seems that this phenomenon is due to the grain size anisotropy.…”

Structural Characterization of Nanocrystalline Ni<sub>(50-x)</sub>Ti<sub>50</sub>Cu<sub>x</sub> (X = 5, 9 wt%) Alloys Produced by Mechanical Alloying

“…Examination of the FWHM values for all the samples revealed the occurrence of anisotropic line broadening. In general, the anisotropic line broadening may be ascribed to the three factors: the presence of stacking faults, the presence of dislocations and nonequivalence of the grain sizes along different crystallographic directions [14]. In our case, it seems that this phenomenon is due to the grain size anisotropy.…”