Iron cobaltite (FeCo2O4) nanocatalysts for water-oxidation: effects of annealing temperature on catalytic properties
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2022
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The development of efficient, stable, and non-precious metal water oxidation catalysts (WOCs)
is a matter of importance for sustainable energy research. In this work, iron cobaltite (FeCo2O4)
nanoparticles were prepared by the coprecipitation method, and we present the effect of heat
treatment (250, 350, 450, 650 and 900 °C) on the catalytic properties. Catalytic activity tests of
FeCo2O4 nanocatalysts were performed in the presence of ammonium cerium(IV) nitrate (CAN),
and the formation of oxygen was followed using a Clark-type oxygen electrode. The samples
were characterized by infrared (IR), thermogravimetric analysis (TGA), powder X-ray diffraction
(XRD) and X-ray photoelectron spectroscopy (XPS), and their surface areas were determined by
the Brunauer, Emmett, and Teller (BET) method. Fourier transform infrared (FTIR) data confirm
a metal-oxygen bond at the octahedral and tetrahedral sites. XRDs data were characteristic of
spinel-like cubic materials. The XPS results confirmed the presence of trivalent and divalent
cobalt and iron ions in the samples and showed that the non-heated sample has a greater amount
of cobalt on the nanoparticles’ surface than those heated to 900 °C. The surface area decreased
from 92.00 m2 g-¹ for the material that was unannealed to 2.00 m2 g-¹ for the sample annealed at 900 °C. The unannealed nanomaterials showed an oxygen production of 790 mmol s−¹ g−¹. This was 790 times greater than the oxygen production from nanomaterials heated to 900 °C.
Although the surface structure of nanomaterials is unclear, the amount of surface cobalt appears
to have implications for catalytic activity. Optimization of superficial cobalt content may be key
to improving catalytic activity.
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Iron cobaltite, Ferrite, Water splitting, Water oxidation catalysis (WOC), Oxygen evolution reaction (OER)
Citação
MAGALHÃES, River S. et al. Iron cobaltite (FeCo2O4) nanocatalysts for water-oxidation: effects of annealing temperature on catalytic properties. Journal of the Brazilian Chemical Society, Campinas, v. 33, n. 10, p. 1163-1171, 2022. DOI: 10.21577/0103-5053.20220036. Disponível em: https://jbcs.sbq.org.br/default.asp?ed=331. Acesso em: 16 jun. 2023.