Strain Effects on Oxygen Reduction Activity of Pr₂NiO₄ Caused by Gold Bulk Dispersion for Low Temperature Solid Oxide Fuel Cells

Abstract

Effects of tensile strain induced by the dispersion of Au nanoparticles in Pr 2 NiO 4 -based oxide on the oxygen reduction reaction were investigated. Au-dispersed Pr 1.9 Ni 0.71 Cu 0.41 Ga 0.05 O 4+δ (PNCG) showed a much decreased cathodic overpotential, and a cell using Au-dispersed PNCG showed a significantly higher power density, approximately 2.5 times higher than that of a cell using PNCG without dispersed Au. The smallest overpotential was achieved at 3−5 mol % dispersion of Au nanoparticles, at which the largest tensile strain was observed. Impedance measurements suggested that the impedance arc in the lower frequency range was mainly decreased; therefore, the increased activity to oxygen reduction was attributed to the increased bulk and surface diffusivity of oxide ions. Electron energy loss spectroscopy (EELS) shows that oxygen in the strained region was in a more reduced state and this oxygen could be assigned to interstitial oxygen which is highly mobile. In addition, density functional theory (DFT) analysis suggested that bond destabilization was attributed to the increase in energy of occupied π* orbitals of surface peroxo species on tensile strained surfaces. Therefore, increased cathodic performance of PNCG by Au nanoparticle dispersion could be assigned to the increased diffusivity by tensile strain.

Surface Segregation in Solid Oxide Cell Oxygen Electrodes: Phenomena, Mitigation Strategies and Electrochemical Properties

“…In addition, Jalili et al [108] grew a 10-nm-thick LSM film onto (001) STO and (001) LAO substrates using PLD to generate in-plane tensile strain and in-plane compression strain, respectively, and observed a higher tendency for SrO segregation and higher concentrations of surface oxygen vacancies on the tensile strained LSM surface due to the larger spacing available for Sr cation accommodation and the reduced elastic energy on the surface as compared with the bulk. This positive effect of tensile strain on increasing oxygen diffusivity has also been reported on Au dispersed Pr 1.9 Ni 0.71 Cu 0.41 Ga 0.05 O 4+δ [109] and La 0.8 Ce 0.1 Ni 0.4 Ti 0.6 O 3 with embedded metal nanoparticles [110], demonstrating that high concentrations of surface oxygen vacancies can play a key role in accelerating SrO segregation.…”

Endogenous Nanoparticles Strain Perovskite Host Lattice Providing Oxygen Capacity and Driving Oxygen Exchange and CH4 Conversion to Syngas

“…How would such materials be made and what would be the impact on the material properties? A recent report shows that by assembling gold nanoparticles together with perovskite oxides (ABO3) in a nanocomposite leads to strain within the perovskite oxide lattice, enhancing oxide ion transport and oxygen reduction activity [1] . Similarly, embedding noble metal nanoparticles within other inorganic crystal lattices enhances electronic transport in a manner analogue to substitutional doping [2] .…”

“…Currently, these are being prepared by assembling metallic nanoclusters together with the non-metallic host lattice. However, this approach is limited to using a combination of metals (usually noble metals) and host lattices that do not interact chemically during preparation [1,11] posing fundamental limitations over the type of materials and nanostructures that can be achieved. An alternative would be to prepare such composites through a controlled disassembly process instead.…”

Self-sustainable protonic ceramic electrochemical cells using a triple conducting electrode for hydrogen and power production

“…PCO is a highly active oxygen electrode in oxygen-ion conducting fuel cells without alkaline earth metal (e.g., Sr or Ba) doping [24][25][26][27] , which tends to mitigate segregation and resulting degradation during operation. Furthermore, lanthanide nickelates receives considerable interest due to their excellent tolerance against high steam vapor and broad oxygen partial pressure 28 . Our experimental study and density function theory (DFT) calculation show that proper Ni replacement in the B-sites of PCO perovskite can surprisingly reduce the migration barrier for proton conduction when proton defects are readily induced by hydration reaction, thus enhancing proton conduction.…”