Enhancing the photocatalytic activity of TiO₂ co-doping of graphene–Fe³⁺ ions for formaldehyde removal
2013
Low, Wasu | Boonamnuayvitaya, Virote
In the present work, graphene and Fe³⁺ ions were doped to enhance the photocatalytic activity of a TiO₂ photocatalyst with the expectation of synergistic effects on the specific surface area and electronic conductivity due to the formation of Ti–O–C bonds preventing charge recombination contributed by graphene and band gap energy narrowing by doping with Fe³⁺ ions. GR/Fe³⁺–TiO₂ was successfully synthesized by the refluxed peroxo titanic acid (PTA) method and was tested for gaseous formaldehyde removal. The results show that graphene contributed to formaldehyde adsorption since the equilibrium adsorption capacity increased with an increasing weight ratio of graphene. The GR/Fe³⁺–TiO₂ photocatalyst with a weight ratio of graphene to TiO₂ (PTA) of 1:50 and the Fe³⁺ dopant at 0.12 wt% was optimal. An equilibrium formaldehyde adsorption capacity of 10.2 mg₍HCHO₎ g⁻¹ (catalyst) and photodegradation efficiency of about 50.3% and 25.5% under UV and visible light irradiation for 90 min, respectively, were obtained. It was observed that the adsorption property of the catalyst was increased by adding graphene and the extendable absorption edge of light to longer wavelengths was attributed to the synergistic effect of graphene and Fe³⁺ dopants on the band gap energy of the catalyst. The greater photocatalytic activity of GR/Fe³⁺–TiO₂ compared to GR–TiO₂ resulted from more hydroxyl (OH) and superoxide (−O2) radicals produced via redox reactions with Fe ions.
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