ABSTRACT
In this work, a solid-state method for the synthesis of perovskite La(FeCuMnMgTi)O3 high-entropy oxide (HEO) nanoparticles is detailed. Additionally, the high performance of these nanoparticles as catalysts in the aerobic and solvent-free oxidation of benzyl alcohol is demonstrated. The structural features of HEO nanoparticles are studied by X-ray diffraction and high-resolution transmission electron microscopy. The La(FeCuMnMgTi)O3 nanoparticles demonstrate excellent benzyl alcohol conversion rates and selectivity for benzaldehyde, reaching 10.6% conversion and 52.8% selectivity after reaction for only 4 h and ≤75.6% conversion after 24 h. In addition, the as-prepared HEO catalyst displays robust stability in benzyl alcohol oxidation. Density functional theory calculations demonstrate that the adsorption energy of benzaldehyde on the HEO surface is lower than that of the benzoic acid. This, in turn, hinders the gradual conversion of benzaldehyde to benzoic acid on the surface of HEO and retains benzaldehyde as the main product.
ABSTRACT
In this work, La(FeCuMnMgTi)O3 HEO nanoparticles with a perovskite-type structure are synthesized and used in the electrocatalytic CO2 reduction reaction (CO2RR). The catalyst demonstrates high performance as an electrocatalyst for the CO2RR, with a Faradaic efficiency (FE) of 92.5% at a current density of 21.9 mA cm-2 under -0.75 V vs a saturated calomel electrode (SCE). Particularly, an FE above 54% is obtained for methyl isopropyl ketone (C5H10O, MIPK) at a partial current density of 16 mA cm-2, overcoming all previous works. Besides, the as-prepared HEO catalyst displays robust stability in the CO2RR. The excellent catalytic performance of La(FeCuMnMgTi)O3 is ascribed to the synergistic effect between the electronic effects associated with five cations occupying the high-entropy sublattice sites and the oxygen vacancies within the perovskite structure of the HEO. Finally, DFT calculations indicate that Cu plays a vital role in the catalytic activity of the La(FeCuMnMgTi)O3 HEO nanoparticles toward C2+ products.