The redox properties of gadolinium doped ceria (CGO) and nickel oxide (NiO) composite cermets underpin the operation of solid oxide electrochemical cells. Although these systems have been widely studied, a full comprehension of the reaction dynamics at the interface of these materials is lacking. Here, in situ Raman spectroscopic monitoring of the redox cycle is used to investigate the interpla...

S olid electrolytes play an important role in several technological applications, such as fuel cells. Optimization of such materials is often done by trial and error. The work of Andersson et al. (1) in this issue of PNAS demonstrates that the choice of dopants can be guided by computer simulations, in which parameters that are essential for the high ionic conductivity are determined from a ser...

We are interested in catalysts consisting either of substitutionally doped oxides (e.g. RuxCe1-xO2) or of submonolayers of an oxide supported on another oxide (e.g. VOx supported on ceria). Calculations and experiments show that in most cases these systems are more active catalysts than the original oxide (i.e. ceria). We use theory to try to find general patterns governing the activation by do...

Numerous approaches have been made to solve the basic transport equation that describes a solid oxide fuel cell (SOFC) with mixed conduction. Classically, the open circuit voltage (OCV) is calculated with Wagner‘s equation, which is right within the limits of linear transport theory. In order to generalize Wagner’s equation, many models have been proposed to describe the current-voltage relatio...

In oxygen conducting ceramics such as cerium-based oxides, O 2diffusion occurs via vacancy hopping. The vacancy concentration can be modulated through doping with aliovalent cations such as Gd 3+ or Pr 3+ . Sluggish ionic conductivity in these electrolytes has been attributed to various defects which increase the activation energy for anion migration. The association of mobile oxygen vacancies ...

The kinetics of CO2 reduction over nonstoichimetric ceria, CeO2-δ, a material of high potential for thermochemical conversion of sunlight to fuel, has been investigated for a wide range of nonstoichiometries (0.02 ≤ δ ≤ 0.25), temperatures (693 ≤ T ≤ 1273 K), and CO2 concentrations (0.005 ≤ pCO2 ≤ 0.4 atm). Samples were reduced thermally at 1773 K to probe low nonstoichiometries (δ < 0.05) and ...

The efficient electro-reduction of CO2 to chemical fuels and the electro-oxidation of hydrocarbons for generating electricity are critical toward a carbon-neutral energy cycle. The simplest reactions involving carbon species in solid-oxide fuel cells and electrolyzer cells are CO oxidation and CO2 reduction, respectively. In catalyzing these reactions, doped ceria exhibits a mixed valence of Ce...