The Formation of Perovskite during the Combustion of an Energy-Rich Glycine-Nitrate Precursor

Analysis of the photocatalytic activity of La0.9Sr0.1Fe0.8Co0.2O3±δ perovskite as a catalyst in the degradation of RB-5 dye

The photocatalytic efficiency of some semiconductors depends mainly on their morphological, optical, and structural properties, which can be modified by varying the calcination temperature. In order to evaluate how these properties change, as a function of temperature in a AA'BB'O3 perovskite material, La0.9Sr0.1Fe0.8Co0.2O3±δ (LSFC) was synthesized by the Pechini method and calcined at different temperatures (600 °C, 700 °C, 800 °C, and 900 °C). All the samples were characterized structurally, morphologically, and optically by XRD, SEM, and UV-Vis spectroscopy. Additionally, specific surface area and pore size distribution were calculated by BET and BHJ methods. LSFC was evaluated as photocatalyst material, estimating the degradation of reactive black 5 (RB5), employing as irradiation source UV light and sunlight. The obtained results display a clear tendency between the photoactivity and the heat treatment: degradation percentage decreases as the calcination temperature increases mainly due to the crystal and grain size and, furthermore, loss of porosity and the decrease in surface area, affecting the photocatalytic activity (98%, 95%, 74%, and 50% degradation, respectively). All the ceramic samples follow a pseudo-first-order reaction.

CO2 Methanation: Solvent-Free Synthesis of Nickel-Containing Catalysts from Complexes with Ethylenediamine

CO₂ methanation was studied in the presence of nickel catalysts obtained by the solid-state combustion method. Complexes with a varying number of ethylenediamine molecules in the coordination sphere of nickel were chosen as the precursors of the active component of the catalysts. Their synthesis was carried out without the use of solvents, which made it possible to avoid the stages of their separation from the solution and the utilization of waste liquids. The composition and structure of the synthesized complexes were confirmed by elemental analysis, IR spectroscopy, powder XRD and XPS methods. It was determined that their thermal decomposition in the combustion wave proceeds in multiple stages with the formation of NiO and Ni(OH)₂, which are reduced to Ni⁰. Higher ethylenediamine content in the complex leads to a higher content of metal in the solid products of combustion. However, different ratios of oxidized and reduced forms of nickel do not affect the initial activation temperature of nickel catalysts in the presence of CO₂. It was noted that, after activation, the sample obtained from [Ni(C₂H₈N₂)₂](NO₃)₂ exhibited the highest activity in CO₂ methanation. Thus, this complex is a promising precursor for CO₂ methanation catalysts, and its synthesis requires only a small amount of ethylenediamine.

Lanthanum-based double perovskite nanoscale motifs as support media for the methanol oxidation reaction

We have correlated the performance of double perovskite metal oxides as support media for the methanol oxidation reaction (MOR) with their intrinsic size, shape, and composition.