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ACS nano 16(6), 8904 - 8916 (2022). doi:10.1021/acsnano.1c11111, In this paper, we show how the composition of bimetallic Fe–Ni exsolution can be controlled by the nature and concentration of oxygen vacancies in the parental matrix and how this is used to modify the performance of CO$_2$-assisted ethane conversion. Mesoporous A-site-deficient La$_{0.4}$Sr$_{0.6−α}$Ti$_{0.6}$Fe$_{0.35}$Ni$_{0.05}$O$_{3±δ}$ (0 ≤ α ≤ 0.2) perovskites with substantial specific surface area (>40 m$^2$/g) enabled fast exsolution kinetics (T < 500 °C, t < 1 h) of bimetallic Fe–Ni nanoparticles of increasing size (3–10 nm). Through the application of a multitechnique approach we found that the A-site deficiency determined the concentration of oxygen vacancies associated with iron, which controlled the Fe reduction. Instead of homogeneous bimetallic nanoparticles, the increasing Fe fraction from 37 to 57% led to the emergence of bimodal Fe/Ni$_3$Fe systems. Catalytic tests showed superior stability of our catalysts with respect to commercial Ni/Al$_2$O$_3$. Ethane reforming was found to be the favored pathway, but an increase in selectivity toward ethane dehydrogenation occurred for the systems with a low metallic Fe fraction. The chance to control the reduction and growth processes of bimetallic exsolution offers interesting prospects for the design of advanced catalysts based on bimodal nanoparticle heterostructures., Published by Soc., Washington, DC

The kinetics of deposition (adsorption, surface reaction) of molybdenum−oxo species on the surface of γ-alumina was studied at various pH's, impregnation temperatures, solute concentrations, and ionic strengths. The kinetic study confirmed the findings of the thermodynamic study performed previously concerning the influence of the aforementioned parameters on the extent of the Mo(vi) deposition and the mechanism of that deposition as well. It was found that the decrease in pH and ionic strength and the increase in the impregnation temperature increase the time required in order for the surface of the support to be saturated by the molybdenum−oxo species. Moreover, the kinetic study suggested that, at low pH's where adsorption predominates, the polymeric oxo species are exclusively adsorbed in the first 20 min and the deposition proceeds through the adsorption of the monomeric oxo species. This is expected to be very useful in designing the preparation of the molybdenum-supported γ-alumina catalysts. The s...