Enhancing the photocatalytic activity of TiO_2 co-doping of graphene-Fe~(3+) ions for formaldehyde removal

摘要

In the present work, graphene and Fe~(3+) ions were doped to enhance the photocatalytic activity of a TiO_2 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 Fe~(3+) ions. GR/Fe~(3+)-TiO_2 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/Fe~(3+)-TiO_2 photo-catalyst with a weight ratio of graphene to TiO_2 (PTA) of 1:50 and the Fe~(3+) dopant at 0.12 wt% was optimal. An equilibrium formaldehyde adsorption capacity of 10.2 mg_((HCHO)) g ~(-1)_(catalyst)catalyst and photo-degradation 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 Fe~(3+) dopants on the band gap energy of the catalyst. The greater photocatalytic activity of GR/Fe~(3+)-TiO_2 compared to GR-TiO_2 resulted from more hydroxyl (*OH) and superoxide (O_2 ~-)radicals produced via redox reactions with Fe ions.