Interaction of O₂ with LSM–YSZ Composite Materials and Oxygen Spillover Effect

Abstract

The interaction between gas-phase oxygen and LSM−YSZ (LSM is La 0.6 Sr 0.4 MnO 3±δ ; YSZ is ZrO 2 •Y 2 O 3 electrolyte) composite catalytic materials was studied by the in situ method based on isotope equilibration with the gas phase at T = 600−850 °C and pO 2 = 0.2−1.3 kPa. We made an attempt to develop mathematical criteria to prove the appearance of the spillover effect [migration of adsorbed particles from the active phase to triple-phase boundary (TPB)] from the experimental data. The heterogeneous exchange rate (r H ) and the three exchange types (r 0 , r 1 , r 2 ) were calculated, where 0, 1, and 2 differ in the number of surface oxide atoms participating during one elementary exchange act. The heterogeneous exchange rate for lanthanum−strontium manganite was 2.5−3 orders higher than the heterogeneous exchange rate for the zirconia-yttria electrolyte over the investigated temperature range. The exchange mechanism of composites LSM−YSZ was different from the LSM and YSZ oxides due to the fact that the ratios between the rates of the three exchange types of composites were also different from the individual phases. An original model was proposed for describing the kinetic dependences taking into account the oxygen exchange at LSM and YSZ individual oxides, at a TPB, and exchange between oxygen forms in an adsorption layer and at a TPB. It was shown, that at 600 °C, the exchange occurred without a significant effect of the exchange on TPB (r TPB ). The exchange on TPB became considerable with increasing temperature, so that at a temperature of 800 °C and higher, the rate-determining stage was the exchange between the forms of oxygen in the adsorption layer and on TPB, corresponding to the spillover effect. The phenomenon of the oxygen spillover effect on LSM−YSZ composites has been considered.

A solvent-induced crystal-facet effect of nickel–cobalt layered double hydroxides for highly efficient overall water splitting

“…A hydrogen/oxygen spillover effect has been observed at the catalyst surface during the different catalytic reactions. 68,69 In this work, the enhancement in the synergistic catalytic effects of bimetallic Co 0.67 Ni 0.33 (OH) 2 for the HER and OER was speculated to be attributed to both the optimized surface electronic structure and the hydrogen/oxygen spillover effect.…”

“…can be ultimately attributed to the change in the surface electronic structure of catalysts, achieving the optimization of surface adsorption energy. 66 However, to our knowledge, the spillover effect 46,[67][68][69] does not involve the changes in the surface electronic structure, but originates from the spilling of intermediates or products from their corresponding optimized adsorption sites to desorption sites, releasing more free active sites for further reactions. A hydrogen/oxygen spillover effect has been observed at the catalyst surface during the different catalytic reactions.…”

H/D isotopic exchange and electrochemical kinetics of hydrogen oxidation on Ni-cermets with oxygen-ionic and protonic electrolytes

“…In the case of the reverse experiment, the procedure was the same; however, the sample was saturated with deuterium, which was exchanged by protium at the beginning of the experiment. The theory of H/D isotope exchange method, based on papers [39,65,66] is described in Supplementary B.…”

Production of butadiene by oxidative butane dehydrogenation with NO: effect of the oxidant species and lattice oxygen mobility in V2O5–WO3/TiO2 catalyst

“…In general, oxygen desorption peaks in the O 2 -TPD profile can be classified into two regions, denoted as α-O (T < 300 °C) and α′-O (300 °C < T < 600 °C). 20,22,[54][55][56] The α-O belongs to the chemisorbed oxygen species that are weakly bonded onto the vacancies of a surface, which could be O 2 − or O − . The α′-O can be ascribed to the superficial lattice oxygen species (e.g., O 2− and O − ) generated from the lattice defects.…”