Hydrothermal synthesis of CaFe2O4/α-Fe2O3 composite as photocatalyst and its photocatalytic activity

Abstract CaFe 2 O 4 /α-Fe 2 O 3 composites with different component ratios have been prepared by hydrothermal method. XRD and SEM were employed to characterize the phase and morphology of the as-sythesized samples. The photocatalytic activity of the obtained samples was evaluated through degradation of methylene blue (MB) under simulative sunlight irradiation, and the transient photocurrent response and the recyclability of the catalysts were also discussed. The results indicated that the microstructures of the obtained composites were short rods and granular particles, and the rods gradually decreased and tended to granular particles with the decrease of Ca content. Compared with single-phase α-Fe 2 O 3 , all the obtained CaFe 2 O 4 /α-Fe 2 O 3 composites displayed significantly enhanced photocatalytic activity, and the sample with the molar ratio of CaFe 2 O 4 :α-Fe 2 O 3  = 1:2 (CF12) exhibited the best photocatalytic activity. The degradation rate of MB over the sample CF12 reached to 95.6% within 180 min, being about 2 times that of single-phase α-Fe 2 O 3 . The enhanced photocatalytic behavior of the composite could be attributed to pn-type heterojunction between CaFe 2 O 4 and α-Fe 2 O 3 which depress the recombination of photogenerated electrons and holes. The outstanding photocatalytic activity and cycling stability of CaFe 2 O 4 /α-Fe 2 O 3 composite suggest it a promising photocatalyst.