Spray‐Flame‐Synthesized LaCo_1−xFe_xO₃ Perovskite Nanoparticles as Electrocatalysts for Water and Ethanol Oxidation

Abstract

Coupling electrochemical generation of hydrogen with the concomitant formation of an industrially valuable product at the anode instead of oxygen can balance the high costs usually associated with water electrolysis. We report the synthesis of a variety of nanoparticulate LaCo1−xFexO3 perovskite materials through a specifically optimized spray‐flame nanoparticle synthesis method, using different ratios of La, Co, and Fe precursor compounds. Structural characterization of the resulting materials by XRD, TEM, FTIR, and XPS analysis revealed the formation of mainly perovskite‐type materials. The electrocatalytic performance of the formed perovskite‐type materials towards the oxygen evolution reaction and the ethanol oxidation reaction was investigated by using rotating disk electrode voltammetry. An increased Fe content in the precursor mixture leads to a decrease in the electrocatalytic activity of the nanoparticles. The selectivity towards alcohol oxidation in alkaline media was assessed by using the ethanol oxidation reaction as a model reaction. Operando electrochemistry/ATR‐IR spectroscopy results reveal that acetate and acetaldehyde are the final products, depending on the catalyst composition as well as on the applied potential.

Towards Mechanistic Understanding of Liquid‐Phase Cinnamyl Alcohol Oxidation with tert‐Butyl Hydroperoxide over Noble‐Metal‐Free LaCo1–xFexO3 Perovskites

“…For oxide nanoparticles prepared by spray‐flame synthesis, the calculation of an average particle size based on the assumption of spherical particles is well justified . Accordingly, average particle sizes of the perovskites between 7 and 13 nm can be estimated, which agree well with our previously reported particle size distributions determined by TEM . The XRD patterns of the synthesized perovskites (Figure ) indicate the presence of a dominant perovskite phase with a minor content of La 2 O 3 .…”

The Effect of Water on the 2‐Propanol Oxidation Activity of Co‐Substituted LaFe1−xCoxO3 Perovskites

“…For LaFe 1‐x Co x O 3 materials, La enrichment on the surface was reported, [38b] as well as on LaFeO 3 [41] . However, STEM‐EDX measurements indicated an A‐cation enrichment as well on the surface [3a] . In contrast, B‐cation enrichment is reported for La 1−x Sr x NiO 3 after thermal decomposition of amorphous citrate materials [42] .…”

Flame-made Particles for Sensors, Catalysis, and Energy Storage Applications

“…The data showed that higher Fe substitution had a lower catalytic activity (ethanol oxidation), while lower Fe substitution offered higher electrocatalytic performance. 97 In another report, cinnamyl alcohol oxidation kinetics with tertiary butyl hydroperoxide (TBHP) over the same LaCo 1– x Fe x O 3 perovskites showed beneficial effects of trivalent Fe in the perovskites. The reaction between liquid-organic moieties was catalyzed heterogeneously by the perovskite produced reactive oxygen species for surface kinetic reaction.…”