The synthesis of Fe2(MoO4)3 by co-precipitation3 . Briefly, iron nitrate nonahydrate (Merck, ≥98%) and ammonium heptamolybdate (Merck, ≥99%) were dissolved separately in demineralized water. The aqueous iron solution was then added dropwise to the molybdate solution while it was stirred. The mixed solutions were stirred for three more hours to complete the precipitation process. The precipitate was first filtered and washed with demineralized water and ethanol and then dried overnight at 100 °C in air. Finally, the powder was calcined in air at 500 °C for 10 h.
For the reference samples, iron (III) oxide (Sigma Aldrich, particle size <5 µm, >96%) was loaded by incipient wetness impregnation with ammonium heptamolybdate tetrahydrate. For that, the iron(III) oxide was dispersed in an aqueous solution of ammonium heptamolybdate tetrahydrate (Fluka, puriss. p. a. >99%) under continuous stirring. The dispersion was dried at 90 °C overnight, followed by calcination at 600 °C for 12 h.
MoO3 was synthesized by calcination of recrystallized ammonium heptamolybdate tetrahydrate (Fluka, puriss. p. a. >99%) at 600 °C for 12 h.
For the reference samples, iron (III) oxide (Sigma Aldrich, particle size <5 µm, >96%) was loaded by incipient wetness impregnation with ammonium heptamolybdate tetrahydrate. For that, the iron(III) oxide was dispersed in an aqueous solution of ammonium heptamolybdate tetrahydrate (Fluka, puriss. p. a. >99%) under continuous stirring. The dispersion was dried at 90 °C overnight, followed by calcination at 600 °C for 12 h.
MoO3 was synthesized by calcination of recrystallized ammonium heptamolybdate tetrahydrate (Fluka, puriss. p. a. >99%) at 600 °C for 12 h.