For γ-FeOOH, 20 mL of Fe(NO3)3 solution (20 mM) was sealed in a glass container, which was then
maintained at 60 °C for 24 h. After centrifuging and washing
with water for 3 times, red brown powder of FeOOH was obtained.
γ-NiOOH was synthesized by oxidizing nickel foam with K2S2O8 in concentrated NaOH (see ref (61 (link))). γ-Fe2O3 was obtained by annealing Fe3O4 nanoparticles (Sigma-Aldrich, CAS number: 1317-61-9) at 300 °C
in air for 12 h. α-Fe2O3 was purchased
from Fluka (CAS number: 1309-37-1). NiFe LDH was synthesized via a
hydrothermal method previously reported by our group (see ref (15 (link))).
maintained at 60 °C for 24 h. After centrifuging and washing
with water for 3 times, red brown powder of FeOOH was obtained.
γ-NiOOH was synthesized by oxidizing nickel foam with K2S2O8 in concentrated NaOH (see ref (61 (link))). γ-Fe2O3 was obtained by annealing Fe3O4 nanoparticles (Sigma-Aldrich, CAS number: 1317-61-9) at 300 °C
in air for 12 h. α-Fe2O3 was purchased
from Fluka (CAS number: 1309-37-1). NiFe LDH was synthesized via a
hydrothermal method previously reported by our group (see ref (15 (link))).
