Preparation of graphene–TiO₂nanocomposite and photocatalytic degradation of Rhodamine-B under solar light irradiation

Abstract

GRÀTiO 2 nanocomposite was prepared by simple chemical method using graphene oxide and titanium isopropoxide (Ti [OCH (CH 3) 2 ] 4) precursors. The crystalline nature of the composite was characterised by powder X-ray diffraction and the intercalation was explained by Raman spectroscopy. The morphology of the composite was analysed by field emission scanning electron microscopy. The elemental and quantitative measurement of the composite was determined by electron dispersive spectroscopy. The shape and size of the particle was measured by transmission electron spectroscopy and high resolution spectroscopy. The surface area and elemental composition of the composite was studied by using BrunauerÀEmmettÀTeller (BET) method and X-ray photoelectron spectroscopy. Photo-generated electrons were studied by photoluminescence spectra. The photocatalytic activity of nanocomposite was investigated by the degradation of Rhodamine-B (Rh-B) in an aqueous solution under solar light irradiation. The GRÀTiO 2 demonstrates photocatalytic activity in the degradation with a removal rate of 98% under solar light irradiation as compared with pure TiO 2 (42%), graphite oxide (19%), and mechanical mixture GR C TiO 2 (60%) due to the increased light absorption intensity and reduction of electronÀhole pair recombination with the intercalation of graphene and TiO 2. The results indicated that the GRÀTiO 2 could be used as a catalyst to degrade Rh-B from coloured wastewater.

Photocatalytic Graphene-TiO2 Thin Films Fabricated by Low-Temperature Ultrasonic Vibration-Assisted Spin and Spray Coating in a Sol-Gel Process

“…The photoconversion performance and degradation rates observed in Figure 10 are consistent with photoinduced current results of Figure 8. It is worth noting that the obtained photoinduced reaction rates of the composite films are comparable with few similar works available in the literature [3,7,18], but in the present study, the films contain both TiO 2 phases and are fabricated using scalable and facile spray coating at much reduced annealing temperatures, achieved by ultrasonic vibration. Figure 11 shows the coordination of graphene with a small amount of oxygen with DMF, reaction of titanium precursor with ethanol and water under acid catalyzing by HCl, and a suggested route for the sol-gel conversion process and transformation of the amorphous TiO 2 to crystalline TiO 2 .…”

“…The peaks at 44.7°, associated with the 105 plane of anatase is present in all composite films, but is weak and slightly shifted in the films with low TiO2 content and annealed at 450 °C [18]. The other peak at 45.4° is due to 211 anatase plane and appears when the film is deposited from the solution with TS:GD of 1:4 and annealed at 150 °C [18]. The reflection peak at 56.6° is assigned to 211 anatase and 105 rutile planes [3,13,15].…”

“…It is found that the abovementioned conditions lead to the same XRD patterns independent of the casting method (spin-SVPT or SVASC). The signals at 31.8 • and 34.6 • represent the graphene oxide and graphene hydroxide perhaps formed during dispersion in organic and oxidative media [2,3,18]. These unwanted bindings deteriorate the optoelectronic performance of the graphene-TiO 2 thin films.…”

“…In another study, incorporation of TiO 2 nanoparticles into graphene sheets was conducted by electrospinning [16]. Posa et al [18] used graphene oxide and titanium isopropoxide to grow anatase on reduced graphene oxide nanosheets. Chemisorption was carried out in an acid-catalyzed sol-gel process which resulted in graphene oxide-TiO 2 , demonstrating superior photocatalytic response.…”

Facile Fabrication of Dumbbell-Like β-Bi2O3/Graphene Nanocomposites and Their Highly Efficient Photocatalytic Activity

“…To date, various graphene–semiconductor composites with enhanced photocatalytic performance have been designed, such as graphene–TiO 2 nanocomposite [10], graphene/zirconium oxide [11] and RGO–Bi 2 O 3 nanocomposite [12]. As far as we know, only a few research studies with graphene-based Bi 2 O 3 used as a photocatalyst have been reported.…”