ZnO rod/reduced graphene oxide sensitized by α-Fe2O3 nanoparticles for effective visible-light photoreduction of CO2

One-Pot Sonochemical Synthesis of ZnO Nanoparticles for Photocatalytic Applications, Modelling and Optimization

“…On the nanoscale, ZnO shows exceptional physicochemical properties that are beneficial in many industrial applications. Many researchers have successfully used ZnO nanostructures in photocatalytic [13][14][15][16], photovoltaic [17][18][19][20], biomedical [21][22][23][24] and sensing [25][26][27][28][29][30][31] applications, as it provides large surface area as compared to its bulk counterpart. The demand of highly efficient, durable and robust photocatalysts for wastewater treatment makes ZnO nanostructures a reliable candidate for photocatalytic applications.…”

Carbon/Graphene-Modified Titania with Enhanced Photocatalytic Activity under UV and Vis Irradiation

“…This is also confirmed by deconvolution of oxygen peak ( Table 2) showing high content of hydroxyl groups on the titania surface. The binding energies of carbon, oxygen and titanium were estimated after deconvolution of C 1s, O 1s and Ti 2p 3/2 peaks into three, three and two peaks, respectively, according to published reports on titania and carbon-modified titania samples [19,24,[50][51][52]. Titanium was present mainly in Ti 4+ form (TiO 2 (C)) and only low content of reduced titanium (Ti 3+ ) was detected, i.e., 0.4%, 0.64% and 1.74% in P25, TiO 2 (C) and G-TiO 2 (C) samples, respectively.…”

“…531.7 eV) and (iii) hydroxyl groups bound to carbon or titanium (C-OH and Ti-OH; at 533.2 eV) [52]. In the case of graphene-modified samples, deconvolution of oxygen into two peaks was reported, i.e., (i) at 532.3 and 531.3 eV for lattice oxygen (Zn-O-Fe for Fe 2 O 3 -ZnO photocatalyst) and O-C bond in rGO, respectively [24], and (ii) at 529.7 and 531.4 eV for lattice oxygen (TiO 2 ) and oxygen in adsorbed hydroxyl groups, respectively [19]. It is clear that oxygen in P25 was mainly in the form of TiO 2 and water or/and carbon dioxide was also adsorbed on titania surface.…”

“…284.4, 286.1 and 288.6 eV, respectively. However, in the case of graphene-modified samples, deconvolution of carbon peak into two peaks was reported, i.e., (i) at 284.6 and 285.3 eV for graphitic carbon (C-C) and rGO (C-OH) [24], and (ii) at 284.5 and 288 eV for C-C/C-H bonds and C=O, respectively [19]. Here, carbon peak could be deconvoluted into three peaks for all samples, but the content of C-O and C=O was the highest in TiO 2 (C) and G-TiO 2 (C) samples, respectively.…”

“…Recently, 2D carbon structures, i.e., graphene (G), graphene oxide (GO) and reduced graphene oxide (rGO), have been proposed for titania modification, due to large specific surface area (efficient reagents adsorption), high conductivity (inhibited charge carriers' recombination by highly mobile electrons), flexible structure and high stability [18]. For example, (i) TiO 2 -GO composite, prepared by thermal hydrolysis of suspension containing GO and titania peroxo-complex, was efficient for photocatalytic degradation of butene in the gas phase [19], (ii) TiO 2 -rGO, synthesized by ionothermal method, was able to generate hydrogen [20], (iii) hydrothermally prepared TiO 2 -rGO and TiO 2 -G decomposed bisphenol A under both UV and vis irradiation [21] and 4-chlorophenol under solar radiation [22], respectively, (iv) ZnO-G, prepared by the Hummers/Offeman/hydrothermal method, caused efficient degradation of cyanide in water under UV, vis, solar and even NIR irradiation (plasmonic absorption of NIR through coupling of graphene) [23] and (v) α-Fe 2 O 3 -ZnO/rGO, synthesized by the Hummer method, redox replacement and electrochemical process, was able to capture and reduce CO 2 to CH 3 OH under vis irradiation [24]. Accordingly, G, GO and rGO-modified titania samples are widely used for photocatalytic applications.…”