Stabilizing Perovskite Structure by Interdiffusional Tailoring and Its Application in Composite Mixed Oxygen-Ionic and Electronic Conductors

Elucidating the Strain-Vacancy-Activity Relationship on Structurally Deformed Co@CoO Nanosheets for Aqueous Phase Reforming of Formaldehyde

Lattice strain modulation and vacancy engineering are both effective approaches to control the catalytic properties of heterogeneous catalysts. Here, Co@CoO heterointerface catalysts are prepared via the controlled reduction of CoO nanosheets. The experimental quantifications of lattice strain and oxygen vacancy concentration on CoO, as well as the charge transfer across the Co-CoO interface are all linearly correlated to the catalytic activity toward the aqueous phase reforming of formaldehyde to produce hydrogen. Mechanistic investigations by spectroscopic measurements and density functional theory calculations elucidate the bifunctional nature of the oxygen-vacancy-rich Co-CoO interfaces, where the Co and the CoO sites are responsible for CH bond cleavage and OH activation, respectively. Optimal catalytic activity is achieved by the sample reduced at 350 °C, Co@CoO-350 which exhibits the maximum concentration of Co-CoO interfaces, the maximum concentration of oxygen vacancies, a lattice strain of 5.2% in CoO, and the highest aqueous phase formaldehyde reforming turnover frequency of 50.4 h^-1 at room temperature. This work provides not only new insights into the strain-vacancy-activity relationship at bifunctional catalytic interfaces, but also a facile synthetic approach to prepare heterostructures with highly tunable catalytic activities.

In situ synthesis of a high-performance bismuth oxide based composite cathode for low temperature solid oxide fuel cells

Here, we report the design and fabrication of a cost-effective and high-performance composite (Bi0.75Y0.25)0.93Ce0.07O1.5±δ-La0.8Sr0.2MnO3 cathode by an in situ synthesis strategy with single-step phase formation and microstructure assembly, which shows lower cathode polarization resistance and better oxygen reduction reaction activity than the conventional LSM-based cathodes for low temperature solid oxide fuel cells.