Sn promoted BaFeO3− catalysts for N2O decomposition: Optimization of Fe active centers

A Double-ligand Chelating Strategy to Iron Complex Anolytes with Ultrahigh Cyclability for Aqueous Iron Flow Batteries

Aqueous all-iron flow batteries (AIFBs) are attractive for large-scale and long-term energy storage due to their extremely low cost and safety features. To accelerate commercial application, a long cyclable and reversible iron anolyte is expected to address the critical barriers, namely iron dendrite growth and hydrogen evolution reaction (HER). Herein, we report a robust iron complex with triethanolamine (TEA) and 2-methylimidazole (MM) double ligands. By introducing two ligands into one iron center, the binding energy of the complex increases, making it more stable in the charge-discharge reactions. The Fe(TEA)MM complex achieves reversible and stable redox between Fe3+ and Fe2+ , without metallic iron growth and HER. AIFBs based on this anolyte perform a high energy efficiency of 80.5 % at 80 mA cm-2 and exhibit a record durability among reported AIFBs. The efficiency and capacity retain nearly 100 % after 1,400 cycles. The capital cost of this AIFB is $ 33.2 kWh-1 (e.g., 20 h duration), cheaper than Li-ion battery and vanadium flow battery. This double-ligand chelating strategy not only solves the current problems faced by AIFBs, but also provides an insight for further improving the cycling stability of other flow batteries.

Modified BaMnO3-Based Catalysts for Gasoline Particle Filters (GPF): A Preliminary Study

Gasoline engines, mainly gasoline direct injection engines (GDI) require, in addition to three-way catalysts (TWC), a new catalytic system to remove the formed soot. Gasoline Particle Filters (GPF) are, among others, a possible solution. BaMnO3 and copper-doped BaMnO3 perovskites seem to be a feasible alternative to current catalysts for GPF. The physical and chemical properties of these two perovskites determining the catalytic performance have been modified using different synthesis routes: (i) sol-gel, (ii) modified sol-gel and iii) hydrothermal. The deep characterization allows concluding that: (i) all samples present a perovskite-like structure (hexagonal), except BMC3 which shows a polytype one (due to the distortion caused by copper insertion in the lattice), and ii) when a low calcination temperature is used during synthesis, the sintering effect decreases and the textural properties, the reducibility and the oxygen mobility are improved. The study of soot oxidation simulating the hardest GDI scenarios reveals that, as for diesel soot removal, the best catalytic performance involves the presence of oxygen vacancies to adsorb and activate oxygen and a labile Mn (IV)/Mn (III) redox pair to dissociate the adsorbed oxygen. The combination of both properties allows the transport of the dissociated oxygen towards the soot.

Strong metal-support interaction promoted scalable production of thermally stable single-atom catalysts

Single-atom catalysts (SACs) have demonstrated superior catalytic performance in numerous heterogeneous reactions. However, producing thermally stable SACs, especially in a simple and scalable way, remains a formidable challenge. Here, we report the synthesis of Ru SACs from commercial RuO2 powders by physical mixing of sub-micron RuO2 aggregates with a MgAl1.2Fe0.8O4 spinel. Atomically dispersed Ru is confirmed by aberration-corrected scanning transmission electron microscopy and X-ray absorption spectroscopy. Detailed studies reveal that the dispersion process does not arise from a gas atom trapping mechanism, but rather from anti-Ostwald ripening promoted by a strong covalent metal-support interaction. This synthetic strategy is simple and amenable to the large-scale manufacture of thermally stable SACs for industrial applications.

SrFe1−xSnxO3−δ nanoparticles with enhanced redox properties for catalytic combustion of benzene

A series of SrFe_1−xSn_xO_3−δ showed high catalytic activity for benzene combustion. The partial substitution of Fe with Sn increased specific surface area and accelerated redox rates of Fe, resulting in the improvement of the catalytic activity.

BaFe1-xCuxO3 Perovskites as Active Phase for Diesel (DPF) and Gasoline Particle Filters (GPF)

BaFe_1−xCu_xO₃ perovskites (x = 0, 0.1, 0.3 and 0.4) have been synthetized, characterized and tested for soot oxidation in both Diesel and Gasoline Direct Injection (GDI) exhaust conditions. The catalysts have been characterized by BET, ICP-OES, SEM-EDX, XRD, XPS, H₂-TPR and O₂-TPD and the results indicate the incorporation of copper in the perovskite lattice which leads to: (i) the deformation of the initial hexagonal perovskite structure for the catalyst with the lowest copper content (BFC1), (ii) the modification to cubic from hexagonal structure for the high copper content catalysts (BFC3 and BFC4), (iii) the creation of a minority segregated phase, BaO_x-CuO_x, in the highest copper content catalyst (BFC4), (iv) the rise in the quantity of oxygen vacancies/defects for the catalysts BFC3 and BFC4, and (v) the reduction in the amount of O₂ released in the course of the O₂-TPD tests as the copper content increases. The BaFe_1−xCu_xO₃ perovskites catalyze both the NO₂-assisted diesel soot oxidation (500 ppm NO, 5% O₂) and, to a lesser extent, the soot oxidation under fuel cuts GDI operation conditions (1% O₂). BFC0 is the most active catalysts as the activity seems to be mainly related with the amount of O₂ evolved during an. O₂-TPD, which decreases with copper content.

Liquid-phase oxidation of alkanes with molecular oxygen catalyzed by high valent iron-based perovskite

Hexagonal BaFeO3-δ containing high valent iron species acted as an efficient heterogeneous catalyst for the aerobic oxidation of alkanes without the need for additives. The activity of BaFeO3-δ was much higher than that of typical Fe3+/Fe2+-containing iron oxide-based catalysts, and the recovered catalyst could be reused without significant loss of catalytic performance.

Morphology-dependent oxygen vacancies and synergistic effects of Ni/CeO2 catalysts for N2O decomposition

Strong morphology-dependent oxygen vacancies and synergistic effects of Ni/CeO₂ catalysts and their vital effects on N₂O decomposition.

Rietveld structure refinement to optimize the correlation between cation disordering and magnetic features of CoFe2O4 nanoparticles

The effects of synthesis parameters on the structural and magnetic features of CoFe₂O₄ nanoparticles have been investigated and their mutual correlations optimized by using response surface methodology.