Titanium Graphene Oxide Research Articles

Reduced graphene oxide-titanium dioxide compact layer prepared via electrodeposition for enhanced performance of dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) as one of the third generation of solar cells have gained great attention due to their inexpensive, easy to fabricate and environmental friendliness. In this study, a reduced graphene oxide-titanium dioxide (rGO-TiO2) compact layer (CL) was prepared by one-step electrodeposition. The presence of the rGO-TiO2 CL had successfully suppressed the dark current and shifted its onset potential to a higher forward bias, indicating a good blocking ability. The photoanode with the rGO-TiO2 CL displayed an improved power conversion efficiency by 96.60% compared to other photoanodes. The incorporation of the rGO-TiO2 CL also increased the electron lifetime and charge collection efficiency compared to the bare TiO2 photoanode. These results demonstrated that rGO-TiO2 CL is a promising material for the enhancement of DSSC performance.

Robust self-cleaning effects of cotton fabrics coated with reduced graphene oxide (RGO)-titanium dioxide (TiO2) nanocomposites

The self-cleaning textiles coated with reduced graphene oxide-titanium dioxide (TiO2) nanocomposites have enhanced photocatalytic activities and could have great potential in practical applications. However, it is still problematic regarding how to avoid aggregation of reduced graphene oxide nanosheets in producing reduced graphene oxide-TiO2 nanocomposites. In this research article, we propose a new method to reduce the aggregation of reduced graphene oxide nanosheets in producing cotton fabrics coated with reduced graphene oxide-TiO2 nanocomposites by combining vibration-assisted ball milling and hydrothermal synthesis process. The microstructure and photocatalytic-related properties of the resultant reduced graphene oxide-TiO2 nanocomposites and their coating cotton fabrics were characterized by using a series of techniques including field emission scanning electron microscope (FESEM), atomic force microscope (AFM), X-ray diffraction spectroscopy (XRD), Raman, particle size distribution, Brunauer-Emmett-Teller,(BET), transmission electron microscope (TEM), X-ray photoelectron spectrometer (XPS), diffuse reflectance spectra (DRS), ultraviolet photoelectron spectroscope (UPS), and photoluminescence (PL). It was indicated that the aggregation of reduced graphene oxide nanosheets in reduced graphene oxide-TiO2 nanocomposites was successfully avoided via ball milling in the presence of tetrabutyl titanate. After hydrothermal treatment, the resulting reduced graphene oxide-TiO2 nanocomposites were firmly immobilized on cotton fabric. It was demonstrated in the self-cleaning experiments that the resultant self-cleaning cotton fabrics are hydrophilic and could directly decompose color contaminants such as methylene blue, Congo red, and coffee stains under simulated sunlight irradiation due to the photo-degradation reactions of the reduced graphene oxide-TiO2 nanocomposite coating. The reduced graphene oxide-TiO2 nanocomposite-modified cotton fabric also exhibited excellent performance in both robust abrasion resistance and soap-washing resistance. The fabric photocatalytic self-cleaning capability was not found to decrease significantly after being repeatedly used for five times.

Degradation kinetics and removal efficiencies of pharmaceuticals by photocatalytic ceramic membranes using ultraviolet light-emitting diodes

The development of ultraviolet light-emitting diode (UV-LED) technology provides more potential for the application of photocatalytic membranes. In this study, graphene oxide-titanium dioxide (GO-TiO2) photocatalytic ceramic membranes were prepared and activated by UV-LED. We systematically evaluated the removal of naproxen (NAP), carbamazepine (CBZ) and diclofenac (DCF) under 365 nm, 300 nm and 275 nm UV-LED irradiation in photocatalytic ceramic membrane reactors (PCMRs). Our results showed that this GO-TiO2 modified ceramic membrane achieved simultaneous separation and photocatalytic degradation for tested pharmaceuticals. Through fluence-based and energy-based efficiencies analysis, the 300 nm UV-LED is a good option for achieving a high removal efficiency with low energy consumption. Membrane filtration enhanced the degradation efficiency by four times through enhancing the mass transfer effect in membrane pores, and reduced the electrical energy per order (EEO) by a factor of ten. In addition, high membrane flux, high degradation rate and strong catalytic stability could be simultaneously achieved in closed-loop dead-end filtration. The addition of H2O2 could further increased the removal efficiency. PCMRs equipped with UV-LEDs are promising for pharmaceuticals removal as well as solving the issue of membrane concentrated water.

Improving pitting corrosion resistance of the commercial titanium through graphene oxide-titanium oxide composite

Titanium oxide has been commonly used for wide range of applications due to excellent corrosion resistance. This study presents the impact of graphene oxide (GO) addition to titanium oxide as coating materials during titanium anodization process on the corrosion behaviour. The GO was prepared by electrochemical exfoliation using low voltage mode in a sodium sulphate electrolyte, which is easier and more environmentally friendly compared to the chemical approach. Raman and scanning electron microscope were used to examine the success of the exfoliation process. The surface morphologies and potentiodynamic polarization results indicate that the addition of GO significantly inhibit the pitting corrosion and stabilize passivation current densities over wide ranges of anodic potentials. The untreated titanium, however, noticeably displayed fluctuation of anodic current densities, confirming the presence of pitting corrosion. The results obtained by electrochemical impedance spectroscopy (EIS) also confirm that the addition of GO enhanced corrosion protection even at higher frequency ranges. The cyclic polarization scan results show a positive shift in the re-passivation potential Erep after the addition of GO. This work emphasizes that the addition of GO during anodization of titanium not only protect its surface from pitting corrosion but also provide a strong passive layer.

Improvement of Hydrophilicity for Polyamide Composite Membrane by Incorporation of Graphene Oxide-Titanium Dioxide Nanoparticles.

In this work, the polyamide (PA) membrane surface has been modified by coating of nanomaterials including graphene oxide (GO) and titanium dioxide (TiO2) to enhance membrane separation and antifouling properties. The influence of surface modification conditions on membrane characteristics has been investigated and compared with a base membrane. Membrane surface properties were determined through scanning electron microscope (SEM) images and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. Membrane separation performance was determined through the possibility for the removal of methylene blue (MB) in water. Membrane antifouling property was evaluated by the maintained flux ratios (%) after 120 minutes of filtration. The experimental results showed that the appearance of hydrophilic groups after coating of GO and TiO2 nanocomposite materials with or without UV irradiation onto membrane surface made an improvement in the separation property of the coated membranes. The membrane flux increased from 28% to 61%; meanwhile, the antifouling property of the coated membranes was improved clearly, especially for UV-irradiated PA/GO-TiO2 membrane.

In vitro Cytotoxicity Analysis of Hybrid Graphene Oxide (hGO) Nano Structures in Caprine Wharton’s Jelly Derived Mesenchymal Stem Cells (WJ-MSCs)

Background: Nanotechnology is used in stem cell culture as well as in vivo delivery and tracking of stem cells. Graphene oxide (GO) is a carbon based nanomaterial and it has large surface area as well as good biocompatibility and heteroatoms doped GO exploit its properties. Hybrid GO (hGO) nano structures biocompatibility is depends on its size, dose and exposure time as well as in vitro cell models and hence, need thorough cytotoxicity studies in different species in vitro cell models. Methods: Caprine Wharton’s jelly derived mesenchymal stem cells (WJ-MSCs) were isolated, characterized and dose dependent (100, 50, 25, 10 and 0µg /ml) in vitro cytotoxicity of three different hGO nano structures (phosphorus doped graphene oxide titanium oxide tubes, rods and sheets) were analysed in caprine WJ-MSCs by studying cell cytotoxicity assays. Result: All three hGO nano structures were damaged cell morphology at 100 and 50 µg /ml doses, however, morphologically more good cells were observed in hGO tubes treated group than hGO rods and hGO sheets at 25 and 10 µg/ml doses as compared to control. Cell viability percentage was significantly (P less than 0.01) decreased at dose 100 µg/ml and it was significantly (P less than 0.01) increased at 25 µg/ml dose as compared to 50, 10 and 0 µg/ml doses. But, hGO tubes significantly (P less than 0.01) increased cell viability % as compared to hGO rods and hGO sheets. Cell population doubling time (PDT) was not altered significantly by all hGO nano structures, but 100 and 50 µg/ml doses significantly (P less than 0.01)increased cell PDT as compared to 25, 10 and 0 µg/ml doses. All hGO nano structures were non significantly altered growth curve, however, all hGO nano structures at 25 µg /ml dose altered (inclined) shape of growth curve, while 100 and 50 µg /ml doses significantly declined growth curve shape as compared to 10 and 0 µg /ml doses. Cell proliferation % was significantly (P less than 0.01) increased at 25 and 10 µg/ml doses, while, it was significantly (P less than 0.01) decreased at 100 µg /ml dose as compared to 50 and 0 µg /ml. However, there was no significance difference was observed in cell proliferation % in groups treated by different hGO nanostructures. In last, it was concluded as, hGO nano structures cytotoxicity was dose dependent and hGO nano tubes were least cytotoxic in caprine WJ-MSCs.

Dye sensitized solar cell (DSC) based on reduced graphene oxide (rGO)-TiO2 nanocomposite photoelectrode and polyaniline (PANI) counter electrode

We report the successful application of reduced graphene oxide–titania (rGO–TiO2) nanocomposite as an efficient photoelectrode and an inexpensive polyaniline (PANI) synthesized by in-situ polymerization on graphite foam as a platinum substitute for tri-iodide reduction for dye‐sensitized solar cell (DSC). The bulk carrier concentration and conductivity of the PANI was measured to be 3.02x1017cm-3 and 4.89x10-1 W-1cm-1 respectively. Subsequently, three DSCs were assembled with rGO–TiO2 nanocomposite photoelectrode and PANI as counter electrode for one and the other two assembled using unmodified TiO2 photoelectrode with PANI and platinum as counter electrodes, respectively. The rGO loading allows more dye to be adsorbed due its large surface area thus improving the light harvesting efficiency (LHE). This improvement in LHE increases the short circuit current density (JSC). The JSC increase is more substantial compared to the reduction in VOC; thus, the increase in the efficiency of the cell with rGO-TiO2 nanocomposite electrode. The short circuit current density for the rGO-TiO2 DSC with PANI counter electrode is 0.45mAcm-2 while that for the unmodified TiO2 DSCs with PANI counter electrode and platinum counter electrode are 0.11mAcm-2 and 0.10 mAcm-2 respectively. This corresponds to 76% increase in the current density and it increases collection rate at the photoelectrode leading to enhanced power conversion efficiency of 0.13% compared with 0.04% and 0.02% for the DSCs assembled with unmodified TiO2 under full sunlight illumination (100 mW/cm2, AM 1.5G) as a result of the better charge collection efficiency of rGO, which reduces the back electron transfer process. This represent 69% enhancement of energy conversion efficiency in the DSC consisting of rGO modified TiO2

Dye sensitized solar cell (DSC) based on reduced graphene oxide (rGO)-TiO2 nanocomposite photoelectrode and polyaniline (PANI) counter electrode

We report the successful application of reduced graphene oxide–titania (rGO–TiO2) nanocomposite as an efficient photoelectrode and an inexpensive polyaniline (PANI) synthesized by in-situ polymerization on graphite foam as a platinum substitute for tri-iodide reduction for dye‐sensitized solar cell (DSC). The bulk carrier concentration and conductivity of the PANI was measured to be 3.02x1017cm-3 and 4.89x10-1 W-1cm-1 respectively. Subsequently, three DSCs were assembled with rGO–TiO2 nanocomposite photoelectrode and PANI as counter electrode for one and the other two assembled using unmodified TiO2 photoelectrode with PANI and platinum as counter electrodes, respectively. The rGO loading allows more dye to be adsorbed due its large surface area thus improving the light harvesting efficiency (LHE). This improvement in LHE increases the short circuit current density (JSC). The JSC increase is more substantial compared to the reduction in VOC; thus, the increase in the efficiency of the cell with rGO-TiO2 nanocomposite electrode. The short circuit current density for the rGO-TiO2 DSC with PANI counter electrode is 0.45mAcm-2 while that for the unmodified TiO2 DSCs with PANI counter electrode and platinum counter electrode are 0.11mAcm-2 and 0.10 mAcm-2 respectively. This corresponds to 76% increase in the current density and it increases collection rate at the photoelectrode leading to enhanced power conversion efficiency of 0.13% compared with 0.04% and 0.02% for the DSCs assembled with unmodified TiO2 under full sunlight illumination (100 mW/cm2, AM 1.5G) as a result of the better charge collection efficiency of rGO, which reduces the back electron transfer process. This represent 69% enhancement of energy conversion efficiency in the DSC consisting of rGO modified TiO2

Effective removal of the rare earth element dysprosium from wastewater with polyurethane sponge-supported graphene oxide–titanium phosphate

Recycling methods will be essential for the future circular economy in the context of declining natural resources. Nanomaterials are promising adsorbents to recover rare earth elements from wastewater, yet the practical application of nanomaterials is limited by spontaneous agglomeration, easy collapse of structures and the difficulty in collecting nanomaterials after adsorption. To solve these issues, we prepared a polyurethane sponge-supported titanium phosphate with graphene oxide, abbreviated as GO@TiP-Sponge, by in situ precipitation. GO@TiP-Sponge was characterized by X-ray diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, and tested for the removal and recovery of trace dysprosium Dy(III), a rare-earth element, in water using batch experiments. Results show that the GO@TiP-Sponge showed an excellent affinity for dysprosium with theoretical capacity reaching 576.17 mg/g according to the Langmuir model. Half-equilibrium was reached in 2.5 min according to a pseudo-second-order model. GO@TiP-Sponge also displayed an adsorption ability for a wide range of pH and salinity. Such performance is explained by strong binding of phosphate with Dy(III), enhanced surface area induced by graphene oxide and less aggregation from the spongy structure. The main adsorption mechanism involves electrostatic interaction.

Reduced Graphene Oxide–Titanium Dioxide Nanocomposites: Structural Characterization and Photocatalytic Degradation of Gaseous Formaldehyde

TiO2/rGO nanocomposites are prepared by the solvothermal process using titanium sulfate and graphene oxide (GO) as raw materials utilized for the photodegradation of gaseous formaldehyde. Characterization by Fourier‐transform infrared (FTIR) spectroscopy, Raman spectroscopy and X‐ray photoelectron spectroscopy (XPS) reveal that GO is partially reduced to reduced GO (rGO) and TiOC bond is formed between TiO2 and rGO. X‐ray diffraction (XRD) confirms that the presence of anatase TiO2. High‐resolution transmission electron microscopy (HRTEM) exhibits that TiO2 nanoparticles with a diameter of ≈20 nm are uniformly loaded on the wrinkled rGO sheets. UV‐vis spectroscopy reveals that the absorption intensity of TiO2/rGO increases with increasing GO content. Photoluminescence (PL) spectroscopy indicates that the ability of restraining electron–hole recombination initially increases with increasing GO content, followed by a gradual decrease. The TiO2/rGO nanocomposite (mTiO2:mGO = 40:1) demonstrates optimal photocatalytic performance with formaldehyde degradation rate of 96% in 2 h and stable activity, which can be ascribed to the larger reduction of GO (76.19%), higher TiOC bonds (17%), unfolded rGO sheets, and lower electron–hole recombination rate.

Characterization and study of CdS quantum dots solar cells based on Graphene-TiO2 nanocomposite photoanode

The CdS sensitized quantum dots solar cells graphene oxide-titanium dioxide (GO-TiO2) nanocomposite photoanode have been fabricated using a solvent modified successive ionic layer adsorption and reaction method. The graphene has a large absorption band of white light for that we have used graphene for graphene-TiO2 nanocomposite. The graphene-TiO2 nanocomposite photoanode has been deposited onto FTO using doctor blade method as a photoanode to obtained a negative capacitance. Quantum dots could increase the efficiency of solar cells and make it possible to capture the energetic electrons and transmit them to the material type acceptor such as the TiO2 has been used for severely photovoltaic cells (PV-cells). From a single absorbed photon upon relaxation of the primary electron-hole pair excited by light the GO can create a lot number of pairs of electron-hole. So that the excess excitation energy will not be lost in the form of phonons or heat, The GO transfers the excess excitation energy to other carriers to produce hot charge carriers in the conduction band of the acceptor material. The particular behavior from the positive to negative capacitance due to the injection of carriers charges from the FTO electrode into TiO2 has been confirmed by the experimental measurement of the capacitance versus voltage (C-V). We have simulated the I-V and P-V characteristics of equivalent circuits of the solar cell. By using the method of Newton-Raphson the studied models are then employed through the involvement by writing matlab programs.

Bimetallic PtCu-decorated reduced graphene oxide (RGO)-TiO2 nanocomposite for efficient oxygen reduction reaction

To exploit the full advantages of electrocatalysts for fuel cell reactions, a promising support is essential to disperse electrocatalytically active metal nanoparticles. Here, at first a graphene oxide-titanium dioxide composite support (GO-TiO2) is fabricated by a sol–gel method. Later, a facile chemical reduction method is demonstrated to simultaneously reduce Pt4+, Cu2+ and GO-TiO2 to form bimetallic PtCu nanoparticles (15 wt% Pt + 5 wt% Cu) on a reduced graphene oxide-titanium dioxide (RGO-TiO2) composite support. A combined action of ethylene glycol and ascorbic acid play a positive role in attaining well dispersed PtCu with a size of 7 nm particles on RGO-TiO2 sheets. The resulting PtCu/RGO-TiO2 nanocomposite exhibits superior electrode-area normalized ORR limiting current density (6.14 mA/cm2-geo) when compared to commercial Pt/C (3.61 mA/cm2-geo) and in-house synthesized PtCu/RGO (4.68 mA/cm2-geo) and Pt/RGO (3.95 mA/cm2-geo) catalysts. The synthesized catalysts are characterized for structural, morphological and surface elemental features by using a combination of diffraction, spectroscopy and electron microscopy techniques. The positive role played by PtCu and RGO-TiO2 composite support assists the improved ORR activity. The versatile synthesis methodology presented here is convenient to fabricate other similar electrocatalytic nanostructures for fuel cell reactions.

Enhanced photocatalytic degradation of antimicrobial triclosan using rGO–TiO2 composite under natural solar illumination

In the present study, the enhancement in the photocatalytic degradation of triclosan after incorporation of reduced graphene oxide (rGO) in pristine TiO2 is investigated. Triclosan is an antimicrobial compound found in commonly used personal care products. The study involved the synthesis of reduced graphene oxide–titania composite using the improved Hummer and hydrothermal methods. The optimum rGO content in the composite was found to be 10 wt% (RT10). The composite was characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, Scanning electron microscopy (SEM), and Brunauer–Emmett–Teller surface area (BETSA). The experimental conditions viz. catalyst dose, initial triclosan concentration, and solution pH were studied. The surface area of the composite was substantially higher than either of TiO2 and GO. The photocatalytic reaction followed pseudo-first-order kinetics with the highest rate constant of 0.251 h−1 obtained for RT10. The scavenging experiment indicated the role of hydroxyl radical in the degradation mechanism. The composite displayed efficient degradation under natural sunlight attributed to narrowing of band gap. It also performed effectively in secondary effluent containing triclosan despite matrix effect. Thus, the composite has potential application as a promising photocatalyst in tertiary treatment of water and wastewater.

Investigating the engine performance, emissions and soot characteristics of CI engine fueled with diesel fuel loaded with graphene oxide-titanium dioxide nanocomposites

Despite progress in the use of electric motors for transportation systems, petro-diesel remains the primary fuel for driving heavy machinery across numerous economic sectors. In this study, the performance, combustion and emissions characteristics, and soot morphology of compression ignition (CI) engine running on diesel fuel, with different nanoparticles were investigated. Three different nanoparticles with a concentration of 50 mg/l were considered. These are graphene oxide (GO), titanium oxide (TiO2) and GO doped with TiO2 (GO-TiO2). The experiments were carried out on a single-cylinder, air-cooled, 4-stroke CI engine at a speed of 2000 rpm, and different engine loads. The soot was sampled from the exhaust line on a fiberglass substrate, using a vacuum pump, and its morphology was observed with a high-resolution transmission electron microscope (HR-TEM). The results showed a 12% average reduction in fuel consumption for diesel/TiO2 fuel compared to neat diesel. Furthermore, the in-cylinder pressures for all the fuel blends, especially at peak load, are greater than that of neat diesel fuel. The GO nanoparticles led to comparable levels of NOX emissions to those of neat diesel, while TiO2 and GO-TiO2 enhanced the formation of NOX. CO emissions were found to increase with the addition of considered nanoparticles. The fringe length and tortuosity were shown to increase for D100+GO-TiO2 compared to diesel fuel by 11% and 7%, respectively. A sparse fringe pattern was also observed for the D100+GO-TiO2 agglomerate. This indicates a more reactive soot, due to the presence of oxygen atoms supplied by the nanoparticles during combustion.

Polyurethane nanofibrous membranes decorated with reduced graphene oxide–TiO2 for photocatalytic templates in water purification

We hereby report a reduced graphene oxide–titanium dioxide (rGO–TiO2)-loaded polyurethane (PU) nanofibrous membrane having visible-light-responsive photocatalytic activity and antifouling property. The functionality is significantly augmented by the hybridization of rGO–TiO2 with nanofibrous membrane. This results in a synergistic combination of high surface area of nanofiber and unique photocatalytic activity of rGO–TiO2. 10 wt% rGO–TiO2-loaded membrane showed an average fiber diameter of 271.83 ± 11.38 nm. Both the thermal stability and mechanical stability of the membrane increase after rGO–TiO2 loading. The optimized PU/10rGO–TiO2 membrane exhibited a water flux of 12810 ± 49.65 Lm−2 h−1, oil rejection of 85.50%, and flux recovery ratio of 88.10%. Theoretical evaluation of fouling model suggests that all the membranes follow cake filtration model. The photocatalytic activity of nanofibrous membrane increases with an increase in rGO–TiO2 concentration in the membrane, and PU/10rGO–TiO2 nanofibrous membrane showed 95% of degradation against methylene blue dye. Thus, the prepared membrane can be suggested for an ideal candidate for antifouling and photocatalytic templates in water filtration systems.

Photoelectrochemical degradation of perfluorooctanoic acid (PFOA) with GOP25/FTO anodes: Intermediates and reaction pathways

Perfluorooctanoic acid (PFOA) have been widely studied due to their persistence, bioaccumulation and possible toxic effects. In this work, we investigated a photoelectrochemical (PEC) system consisting of a graphene oxide-titanium dioxide (GOP25) anode coated on fluorine-doped tin oxide (FTO) glass for removal of PFOA in an aquatic environment. The GOP25/FTO anode was fabricated and well characterized. Nearly complete decomposition of 0.5 mg/L PFOA was achieved after 4 h of PEC treatment with an initial pH of 5.3 and a current density of 16.7 mA cm−2. The presence of graphene oxide (GO) on the TiO2 anode could enhance its electrochemical performance, thereby leading to increased decomposition efficiency. A total of 18 PFOA transformation products, including short-chain perfluoroalkyl acids, are reported in this work, and 13 products were observed for the first time. Four possible routes of PFOA decomposition, namely, decarboxylation followed by oxidation, defluorination, hydroxylation and Cl atom substitution, were determined. The presence of chlorinated byproducts in the system indicated that reactive chlorine species contributed to PFOA degradation.

Graphene Oxide Decorated with Titanium Nanoparticles to Reinforce the Anti-Corrosion Performance of Epoxy Coating

Graphene oxide–titanium (GO-Ti) composite materials were fabricated using GO as a precursor and then anchoring nano titanium (Nano-Ti) particles on GO sheets with the help of a silane coupling agent. Then, the coating samples were prepared by dispersing GO, Nano-Ti particles, and GO-Ti in an epoxy resin at a low weight fraction of 1 wt %. The GO-Ti composites were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The dispersibility and anti-corrosion mechanism of the coatings were studied by sedimentation experiments, electrochemical impedance spectroscopy (EIS), SEM, and salt spray tests. The mechanical properties of the coatings were analyzed by friction and wear tests. The results showed that the Nano-Ti particles were successfully loaded on the GO surface by chemical bonds, which made GO-Ti composites exhibit better dispersibility in the epoxy than GO. Compared with Nano-Ti particles and GO, the GO-Ti composite exhibited significant advantages in improving the corrosion resistance of epoxy coatings at the same contents, which was attributed to the excellent dispersibility, inherent corrosion resistance, and sheet structure. Among the different proportions of composite materials, the GO-Ti (2:1) material exhibited the best dispersibility and corrosion resistance. In addition, the composite material also greatly improved the wear resistance of the coating.

Phytoreduced graphene oxide-titanium dioxide nanocomposites using Moringa oleifera stick extract

The present article reports facile and surfactant-free synthesis of phytoreduced graphene oxide-titanium dioxide (r-GO/TiO2) nanohybrid using Moringa olefera stick extract as a greener reducing agent. The structural properties of synthesized r-GO/TiO2 had been examined by diverse systematic analytical techniques for structural and morphological aspects. The GO can be reduced to rGO by MO and the formation of rGO/TiO2 NC was confirmed by XRD and FT-IR. The DRS revealed that anchoring of TiO2 on graphene surface had promoted the absorption in the visible region. SEM images disclose layer sheet-like and microball-like morphology for rGO and rGO/TiO2 NC respectively. The photoluminescence (PL) characteristic of synthesized r-GO/TiO2 NC was examined and revealed that rGO acts as an electron scavenger and inhibits the recombination of photoelectrons. Radical scavenging activity against 1,1-Diphenylpicryl-hydrazyle (DPPH) studied in methanol, ethanol and ascorbic acid as standard reference using as-synthesized materials was studied. The present study discloses new straightforward greener approach for the manufacturing of rGO-based nanomaterials.

Comparison of graphene oxide titania catalysts for their use in photocatalytic ozonation of water contaminants: Application to oxalic acid removal

In this work, three catalysts constituted by graphene oxide on titania prepared from different methods for their use in photocatalytic ozonation (PhOz) have been compared through their properties determined from well known characterization techniques (SBET, XRD, Raman, TEM, UVVisDRS, XPS, etc) and efficiency to remove oxalic acid as model end product of ozone processes. Comparison has also been made for transfer ozone demand and RCT and RHO,O3 parameters. By considering the reacting system as one irreversible gas–liquid-solid catalytic reaction, a kinetic study has been developed and activation energies of these reactions calculated for two out of three catalysts. Finally, kinetic modelling was also proposed and solved to calculate TOC and ozone concentrations in the gas leaving the reactor and dissolved in water for the three PhOz processes.

Gas sensitivity of heterojunction TiO2NT/GO materials prepared by a simple method with low-concentration acetone

Graphene oxide (GO) was prepared using a modified Hummers' method, and titanium dioxide nanotubes (TiO2NT) were prepared by a hydrothermal method. The gas sensing material (graphene oxide-titanium dioxide nanotubes) was obtained by self-assembling composite GO and TiO2NT.Then the material was coated onto a gold electrode to prepare the device. This resultant device exhibits excellent response to low concentrations of acetone and high selectivity over other gases. Through SEM test analysis, TiO2NT was tiled on a sheet of GO to form a physically bonded heterojunction semiconductor composite. XRD analysis confirms that the anatase TiO2 was successfully produced and there was no impurity peak in the composite. During the gas sensing test, it was proved that the device exhibited an excellent response to 0.3 ppm of acetone at 250 °C. The heterojunction material still exhibits the resistance characteristics of the n-type semiconductor, and the material resistance is reduced in a gas environment by carrier conduction. The increase of sensitivity arises from the fact that the holes of GO and the carriers of TiO2NT are moved towards each other to form a space charge region, which causes the material to form a larger resistance difference in the test gas environment.