In situ synthesis of CNTs/Fe–Ni/TiO2 nanocomposite by fluidized bed chemical vapor deposition and the synergistic effect in photocatalysis

• CNTs/Fe–Ni/TiO2 nanocomposites were synthesized by in situ FBCVD method.
• CNTs were in situ grown on the surface of TiO2.
• The sample synthesized at 500 °C exhibited best photocatalytic activity.
• The probable mechanism of synergistic enhancement on photocatalysis was discussed.

Carbon nanotube (CNTs)/Fe–Ni/TiO2 nanocomposite photocatalysts have been synthesized by an in situ fluidized bed chemical vapor deposition (FBCVD) method. The composite photocatalysts were characterized by XRD, Raman spectroscopy, BET, FESEM, TEM, UV–vis spectroscopy, and XPS. The results showed that the CNTs were grown in situ on the surface of TiO2. Fe(III) in TiO2 showed no chemical changes in the growth of CNTs. Ni(II) was partly reduced to metal Ni in the FBCVD process, and the metal Ni acted as a catalyst for the growth of CNTs. The photocatalytic activities of CNTs/Fe–Ni/TiO2 decreased with the rise of the FBCVD reaction temperature. For the sample synthesized at low FBCVD temperature (500 °C), more than 90% and nearly 50% of methylene blue were removed under UV irradiation in 180 min and under visible light irradiation in 300 min, respectively. The probable mechanism of synergistic enhancement of photocatalysis on the CNTs/Fe–Ni/TiO2 nanocomposite is proposed.

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