Undercoordinated, bridging O-atoms (Obr) are highly active as H-acceptors in alkane dehydrogenation on IrO2(110) surfaces but transform to HObr groups that are inactive toward hydrocarbons. The low C-H activity and high stability of the HObr groups cause the kinetics and product selectivity during CH4 oxidation on IrO2(110) to depend sensitively on the availability of Obr atoms prior to the onset of product desorption. From temperature programmed reaction spectroscopy (TPRS) and kinetic simulations, we identified two Obr-coverage regimes that distinguish the kinetics and product formation during CH4 oxidation on IrO2(110). Under excess Obr conditions, when the initial Obr coverage is greater than that needed to oxidize all the CH4 to CO2 and HObr groups, complete CH4 oxidation is dominant and produces CO2 in a single TPRS peak between 450 and 500 K. However, under Obr-limited conditions, nearly all the initial Obr atoms are deactivated by conversion to HObr or abstracted after only a fraction of the initially adsorbed CH4 oxidizes to CO2 and CO below 500 K. Thereafter, some of the excess CHx groups abstract H and desorb as CH4 above ~500 K while the remainder oxidize to CO2 and CO at a rate that is controlled by the rate at which Obr atoms are regenerated from HObr during the formation of CH4 and H2O products. We also show that chemisorbed O-atoms (“on-top O”) on IrO2(110) enhance CO2 production below 500 K by efficiently abstracting H from Obr atoms and thereby increasing the coverage of Obr atoms available to completely oxidize CHx groups at low temperature. Our results provide new insights for understanding factors which govern the kinetics and selectivity during CH4 oxidation on IrO2(110) surfaces.

Performance comparison of perovskite solar cells with different architectures is nontrivial. J–V sweeps can be unreliable due to stack‐dependent output variations affected by sample preconditioning, scan rate, scan direction, and temperature. Maximum power point tracking is regarded as a more reliable performance measurement. In this study, a two‐step measuring procedure is proposed for quick and unbiased comparison of perovskite‐based solar cells. In the proposed procedure, the transient current density characterization step is used to determine optimal parameters for maximum power point tracking performance characterization. Moreover, factors affecting time limited maximum power point tracking by comparing performance and output of three different maximum power point tracking algorithms applied to devices, from three planar n‐i‐p perovskite stacks, are analyzed and identified. Numerical simulation is used to model differences and define limitations of the algorithms. As a result, it is shown that measurement delay and voltage step can have a crucial effect on maximum power point tracking output, regardless of the chosen algorithm.

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Repeated oxidation and reduction transforms a cubic fluorite Tb2O3(111) film to the bixbyite structure.

Development of an intermediate temperature solid oxide fuel cell essentially require the synthesis of electrocatalytically active nanostructured cathode materials with fast oxygen anion transport and surface exchange properties. Double perovskite structured GaBaCo2O5+δ (GBCO) electrode showing an average particle size of less than 20 nm was synthesized by a bio-milling approach. In parallel, molecular dynamics (MD) simulations were utilised to calculate the effect of Fe doping at the B-site on the oxygen anion diffusivity of GdBaFexCo2-xO5.5 double perovskites. The oxygen diffusion was observed to be preferential in the a-b plane of GBCO with a value of D=2.8 x 10-7 cm2 s-1, calculated at 1173 K. The change in diffusion coefficient (D=1.95 x 10-7 cm2 s-1 at 1173 K) was negligible on doping 50% Fe in the structure. However, in 100% Fe substituted structure, GdBaFe2O5.5 (GBFO5.5), the diffusivity was significantly reduced (D=2 x 10-8 cm2 s-1 at 1173 K).

Determining the accurate power output of perovskite‐based thin film solar cells is dependent on measuring conditions and parameters. In article no. http://doi.wiley.com/10.1002/solr.201800287, Lucija Rakocevic and co‐workers show how the choice of measuring parameters can alter the measured performance in maximum power point tracking. A measuring procedure for comparison of different perovskite‐based nip architectures is proposed.