Presence Of Reduced Graphene Oxide Research Articles

Facile Fabrication of High-Performance Superhydrophobic Reusable Oil-Absorbing Sponges

Wastewater treatment from oil, oil products and organic mixtures is a very relevant topic that can be successfully utilized to solve problems of severe environmental pollution, such as oil spills, industrial oily wastewater discharges and water treatment in the water treatment process. In this work, we have developed new superhydrophobic magnetic polyurethane (PU) sponges, functionalized with reduced graphene oxide (RGO), MgFe2O4 nanoparticles, and silicone oil AS 100 (SO), as a selective and reusable sorbent for the purification and separation of wastewater from oil and organic solvents. The surface morphology and wettability of the sponge surface were characterized by scanning electron microscopy (SEM) and a contact angle analysis system, respectively. The results showed that the obtained PU sponge PU/RGO/MgFe2O4/SO had excellent mechanical and water-repellent properties, good reusability (lasted more than 20 cycles), as well as fast (immersion time 20 s) and excellent absorption capacity (16.61–44.86 g/g), and additional good magnetic properties, which made it easy to separate the sponge from the water with a magnet. The presence of RGO in the composition of the nanomaterial improves the separating and cleaning properties of the materials and also leads to an increase in the absorption capacity of oil and various organic solvents. The synthesized PU sponge has great potential for practical applications due to its facile fabrication and excellent oil–water separation properties.

Wound dressing based on PVA nanofiber containing silk fibroin modified with GO/ZnO nanoparticles for superficial wound healing: In vitro and in vivo evaluations.

Silk fibroin (SF), extracted from Bombyx mori, has unique physicochemical properties to achieve an efficient wound dressing. In this study, reduced graphene oxide (RGO)/ZnO NPs/silk fibroin nanocomposite was made, and an innovative nanofiber of SF/polyvinyl alcohol(PVA)/RGO/ZnO NPs was ready with the electrospinning technique and successfully characterized. The results of MIC and OD analyses were used to investigate the synthesized materials' antibacterial effects and displayed that the synthesized materials could inhibit growth against Staphylococcus aureus and Escherichia coli bacteria. However, both in vitro cytotoxicity (MTT) and scratch wound studies have shown that RGO/ZnO NPs and SF/PVA/RGO/ZnO NPs are not only non-toxic to NIH 3T3 fibroblasts, but also can cause cell viability, cell proliferation, and cell migration. Furthermore, improving the synthesized nanofiber's structural properties in the presence of RGO and ZnO NPs has been confirmed by performing tensile strength, contact angle, and biodegradation analyses. Also, in a cell attachment analysis, fibroblast cells had migrated and expanded well in the nanofibrous structures. Moreover, in vivo assay, SF/PVA/RGO/ZnO NPs nanofiber treated rats and has been shown significant healing activity and tissue regeneration compared with other treated groups. Therefore, this study suggests that SF/PVA/RGO/ZnO NPs nanofiber is a hopeful wound dressing for preventing bacteria growth and improving superficial wound repair.

Improving electrochemical performance of hybrid electrode materials by a composite of nanocellulose, reduced oxide graphene and polyaniline.

Novel ternary composites of polyaniline (PANI), reduced graphene oxide (RGO), and cellulose nanofibers (CNFs) are prepared by a chemical method for hybrid supercapacitors. CNFs were extracted from sugarcane bagasse waste in sugar production, by physicochemical processes. The composites were investigated as electrode-active materials for hybrid supercapacitors. The obtained results revealed that the presence of RGO and CNFs in the composites led to enhanced electrochemical performances, such as capacitance, rate capability, and long-term cyclability of the composite. The optimal composite of CNFs/RGO/PANI with a weight ratio of 4/16/80 can deliver the highest specific capacitance at 566.2 F g-1 under an applied current of 1 A g-1. After 1000 cycles of repetitive charge and discharge, the optimal composite retains 85.4% of its initial capacitance, whereas the PANI electrode obtained only 36.7% under the same conditions. Moreover, the supercapacitive performance is also strongly dependent on the component of the ternary composites. Overall, the composite is a promising material for hybrid supercapacitors; and the CNF component is a renewable material and a product of waste materials.

Jamming carbonaceous nanofiller in the continuous phase and at the blend interface for phenomenal improvement in the overall physico-mechanical properties of compatibilized thermoplastic elastomer

Reduced graphene oxide (RGO) nanosheets have been selectively jammed in the continuous polypropylene (PP) phase and at the blend interface of random terpolymer of ethylene, acrylic ester and maleic anhydride (EAMAT) compatibilized PP and epichlorohydrin rubber (ECH) based thermoplastic elastomer (TPE). The presumptions from the contact angle studies regarding the preferential localization of RGO in the continuous PP phase and at the blend interface of compatibilized PP/ECH/EAMAT/RGO TPE nanocomposite have been analyzed via field emission scanning electron microscopy and atomic force microscopy. The presence of RGO in the continuous PP phase and at the blend interface results in a phenomenal improvement in the mechanical, rheological and viscoelastic properties of the compatibilized PP/ECH/EAMAT/RGO TPE nanocomposites. X-ray diffraction studies of the strained compatibilized PP/ECH/EAMAT/RGO TPE nanocomposite testify that, during straining, the RGO nanosheets help the PP chains to orient and consequently there is a prominent improvement in the overall physico-mechanical properties.

Effect of reduced graphene oxide on mechanical behavior of an epoxy adhesive in glassy and rubbery states

The mechanical behavior of an adhesive, in neat state and reinforced with up to 0.5 wt% of reduced graphene oxide (RGO) was investigated here. Tests were done at temperatures between the ambient temperature and the glass transition temperature ( Tg[Formula: see text] of the adhesive. Using a metal mold, cured plates of the neat and RGO reinforced epoxy adhesive were prepared. The adhesive powder and the bulk dumbbell-shaped specimens, obtained from cured adhesive plates, were subjected to differential scanning calorimetry (DSC) and tensile tests, respectively, to obtain the Tg as well as mechanical properties of the adhesives. The results indicated that adding RGO up to 0.5 wt% increased the glass transition temperature, the modulus of elasticity, and the strength of the adhesive. It was found that the presence of RGO reduced the adhesive’s strain at the break at the ambient temperature. However, at high temperatures, near the Tg, the ultimate strain of RGO-reinforced adhesives decreased slightly when compared to the ultimate strain of the neat specimens. This explains the reduction in toughness at ambient temperature obtained by adding RGO and the increase at high temperatures. Finally, the failure morphology of the neat and RGO-reinforced adhesive specimens was investigated using microscopic imaging of the specimens’ failure cross-sections, which supported and justified the experimental observations.

Bismuth Vanadate Encapsulated with Reduced Graphene Oxide for Hydrogen Peroxide Generation

Hydrogen peroxide (H2O2), a strong oxidant, is considered as a highly value-added chemical due to its diverse applications. The conventional multi-step process for H2O2 production in the industrial setting is energy intensive, using reactants of explosive nature and expensive catalysts. A photocatalytic H2O2 production, in contrast, is a sustainable and eco-friendly process, requiring mostly water, dioxygen (O2), and sunlight. The role of the photocatalyst is to provide the electron for the reduction of O2 and holes for the release of hydrogen ion in water. The main challenge with this approach is the lack of an efficient photocatalyst, which can absorb light and transfer the energy to redox reaction. Bismuth vanadate (BiVO4), a semiconductor with a low band gap energy (~2.4 eV), is known to be a promising photocatalyst. Moreover, reduced graphene oxide (RGO) is well-known for its role in promoting the separation and transport of charges, preventing the recombination of photogenerated electron−hole pairs. This study proposes a method of synthesizing a composite catalyst by functionalizing BiVO4, via the encapsulation with RGO. The catalyst synthesis is optimized by varying the amount of graphene oxide (GO) loading on BiVO4. This paper will summarize the structural, morphological, and photoelectrochemical characterization of these BiVO4-RGO catalysts. Preliminary results have indicated that the H2O2 production is enhanced by 3-fold with the presence of RGO and BiVO4 than BiVO4 alone. The role of carbon doping in improving the light trapping and charge separation, resulting in the enhancement of photocatalytic H2O2 yield, will be examined.

Photoelectrochemical performance of thermally sulfurized CdxZn1-xS photoanode: Enhancement with reduced graphene oxide support

In this study, photoelectrochemical performance of reduced graphene oxide (RGO)-Cd x Zn 1-x S composites, which were synthesized through a novel two-steps thermal sulfurization process by using elemental sulfur, was reported. This is the first time that the two-step thermal sulfurization process with elemental sulfur for the preparation of photoanode based on RGO-Cd x Zn 1-x S. The electrodes exhibited high photostability and photocurrent response in the presence of visible light. The presence of RGO in Cd x Zn 1-x S as electron collector and transporter increased the photocurrents approximately 40%. Among the RGO-Cd x Zn 1-x S composites, RGO-CdS photoanode yielded an extremely high photocurrent density of 6.5 mAcm −2 with the rate of hydrogen production rate of 551.1 μ m o l h − 1 c m − 2 . This value of photocurrent density is almost 89% of its theoretical value. This is the maximum attained photocurrent density with superior stability in comparison with related literature. • CdZnS based photocatalysts were synthesized through thermal sulfurization method. • Photoelectrochemical activity of each photocatalyst has been tested. • ITO/RGO-CdS appeared to be the most active and stable photocatalyst. • ITO/RGO-CdS provides the highest photocurrent density of 6.5 mAcm −2 . • ABPE estimated as 2.67% at V bias = 0V (vs. Pt-electrode).

Enhanced thermoelectric properties of MoS2 with the incorporation of reduced graphene oxide (RGO)

Abstract Molybdenum disulfide (MoS2), a transition metal dichalcogenides (TMDs) is a potential candidate for thermoelectric due to its inherent low thermal conductivity. However, its low electrical conductivity confines its practical usage. In this paper, we have synthesized nanocomposite of MoS2 with reduced graphene oxide (RGO) and demonstrated a ∼5920% increase in the thermoelectric figure of merit of MoS2 after formation of MoS2-RGO nanocomposite. This ultra-high enhanced thermoelectric figure of merit is due to significantly enhanced electrical conductivity, increased Seebeck effect and simultaneous reduction of thermal conductivity of MoS2 in the MoS2-RGO nanocomposite. Presence of RGO in the matrix of MoS2 in MoS2-RGO nanocomposite provides conducting path, reduces interface barrier height and also provides enhanced scattering of phonons.

Metal organic frameworks derived high-performance photoanodes for DSSCs

Metal organic frameworks (MOFs) and reduced graphene oxide (RGO) are used to modify photoanodes of dyes sensitized solar cells (DSSCs) to improve their photovoltaic performances. The MOFs are found that bring about a significant enhancement of the BET area of photoanodes, which endows a high dye adsorption capacity. Moreover, the added MOFs introduces an improved incident photon to electron efficiency because of the remarkably enhanced scattering power for the incident light. On the other hand, in the presence of RGO provides a fast transport channel for photo-induced electrons, which depresses the dark current of the resulting devices. After optimizing the mass fraction of MOFs and RGO, the synergy has been achieved. Moreover, by using a graphene-based counter electrode, the photovoltaic performances of the resulting full-carbon DSSCs are detected. The short-circuit current, open-circuit voltage, fill factor (FF) and energy conversion efficiency (η) reach 18.6 mAcm−2, 682 mV, 0.608 and 7.67%, indicating the potential application prospection of the as-prepared photoanodes.

Production and characterization of graphene/PVC biocomposite from seashell wastes

Sea shell waste are rich resources which contain calcium and organic materials which could be used as reinforcement in biocomposites due to their abundance and inexpensive. Reduced graphene oxide (RGO) is widely used as bio-filler for composites because of its ease synthesis, large surface area and antibacterial property. Therefore, in this work, PVC (polyvinyl chloride) biocomposites were prepared by reinforcing grinded seashell wastes (SS) into PVC matrix in the presence of RGO as a bio-filler. The biocomposites were produced by colloidal blending method. The structural properties of the biocomposites as a function of SS content were investigated. The biocomposites containing 5, 10, 15 and 20 wt% of SS and 0.1 wt% of RGO filled were fabricated. Compositions (% oxide) of the SS were characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), FTIR spectral analysis, Scanning electron microscopy (SEM) images and EDS mapping analysis. All the analysis results showed that SS distribution in the matrix was better at high reinforcement contents (15 and 20 wt%) compared to low contents (5 and 10% by weight). Since better dispersion of RGO and better interfacial interactions between SS and PVC are important factors in enhancing the properties of biocomposites, this study showed that SS and RGO could be effective, green and potentially cost-efficient alternatives to bio-reinforcement and bio-filler materials.

Strategically designed reduced graphene oxide based magnetic responsive nanocatalysts for the attenuation of recalcitrant pollutants

The present work attempts to capture the augmentation in the catalytic activity of ferrite (MFe2O4) nanoparticles by employing reduced graphene oxide (RGO) as its solid support that not only provides space for dispersion but also increases the catalytically active sites of nanoferrites. MFe2O4/xRGO (M = Co, Ni and x = 0, 10, 20, 30, 40 wt% GO) were prepared via facile hydrothermal method and their physical characteristics were probed by FT-IR, XRD, FE-SEM, HR-TEM, VSM and BET analysis. Furthermore, the fabricated samples were explored as versatile catalysts for the remediation of hazardous environmental pollutants via oxidation of a cationic dye, an anionic dye and an antibiotic; and reduction of 2-, 3- and 4-nitrophenol. The catalytic behavior of MFe2O4/xRGO was found to be dependent on presence of RGO as solid support as well as on the amount of GO added. The synergistic interaction between dispersed ferrite nanoparticles and RGO sheet was the reason behind the superior catalytic activity of RGO supported nanoferrites in comparison with pure nanoferrites, whereas the increase in specific surface area accounted for augmented activity with increased GO content. High reaction rates were observed even in the absence of light irradiation using MFe2O4/RGO nanocomposites for oxidation reactions. However, for the reduction of nitrophenols, the introduction of RGO resulted in the transformation of inactive CoFe2O4 into highly active catalysts. Also, the usage of just 2 mol% of RGO supported nanoferrites gave astonishing reduction rates. Moreover, the nanocomposites manifested excellent recyclability furthering the humanitarian cause to remove environmental pollutants.

RGO Boosts Band Gap Regulates for Constructing Ni2P/RGO/MoO2 Z-Scheme Heterojunction to Achieve High Efficiency Photocatalytic H2 Evolution

A Z-scheme heterojunction composite material Ni2P/RGO/MoO2 with high efficiency HER activity via a simple hydrothermal synthesis method which is one-step for photocatalytic H2 production was synthesized. The composite material which used reduced graphene oxide (RGO) as an electron transport medium and utilized a synergistic action of non-noble metal semiconductors Ni2P and MoO2 to construct Z-scheme heterojunction. Compared with the binary Ni2P/MoO2 composite photocatalyst, the photocatalytic hydrogen evolution activity of RGO assisted ternary composite Ni2P/RGO/MoO2 is significantly improved under visible light (λ > 420 nm) in the dye sensitization system in 5 h. The photocatalyst with optimal ratio reaches 355.34 μmol, which is about two times as much as the one without RGO. The transient photocurrent response, fluorescence test and hydroxyl radical capture experiment show that the type-II heterojunction originally composed of Ni2P and MoO2 is converted to Z-scheme in the presence of RGO. The transformation of the electron transfer mode effectively reduces the composite of photogenerated carriers. In addition, in situ hydrothermal synthesis allows Ni2P and MoO2 to be firmly modified on the RGO surface. This makes the composite photocatalyst exhibit great catalytic stability, and the HER activity of the photocatalyst hardly decrease in the four-cycle experiment. Through the one-step hydrothermal method, RGO assisted non-precious metal semiconductor composite provides a new idea for the synthesis of photocatalytic materials. The composite catalyst via the band gap regulation of MoO2 by Ni2P exhibits great hydrogen production activity in the dye-sensitized system. Subsequently, the GO solution was added during the synthesis to construct a Z-scheme heterojunction with graphene as an electron transporter. The ternary composite catalyst with a Z-scheme heterojunction shows approximately twice the hydrogen production rate of the binary catalyst.

Reduced graphene oxide/carbon nanotube hybrid fibers with narrowly distributed mesopores for flexible supercapacitors with high volumetric capacitances and satisfactory durability

Although graphene fiber supercapacitor is promising as an efficient, flexible and lightweight power source for wearable smart electronic devices, it has a limitation of low volumetric capacitance caused by its loose porous structure and unsatisfactory wettability with electrolytes. Herein, continuous hybrid fibers consisting of reduced graphene oxide (RGO) and carbon nanotubes (CNTs) are fabricated as highly capacitive electrodes by wet-spinning of non-liquid-crystal dispersion of graphene oxide and CNTs with the assistance of a capillary orientation apparatus followed by moderate chemical reduction. The addition of the aligned CNTs benefits the construction of a compact structure with narrowly distributed mesopores in the hybrid fibers, enhances tensile strength of the fibers, and improves internal electrical conduction of the fiber electrode, while the presence of RGO provides pseudocapacitance derived from its residual oxygen-containing groups. Consequently, the hybrid fiber supercapacitor with a polyvinyl alcohol/H2SO4 electrolyte delivers not only high volumetric capacitance of 354.9 F cm−3 and high energy density of 12.3 mW h cm−3 at a current density of 0.1 A cm−3, but also exhibits long cycling stability of 94% after 10,000 cycles and satisfactory bending durability. A stable foldable supercapacitor with origami-based structure is well constructed with high prospects in miniaturized flexible and stretchable devices.

High-Performance Supercapacitor Electrode of HNO3 Doped Polyaniline/Reduced Graphene Oxide Nanocomposites

Polyaniline (PANI) nanorods were prepared by a chemical method in the presence of HNO3 as an acid dopant. Reduced graphene oxide (RGO) sheets were synthesized and used as a substrate for the polymerization of PANI, affording the PANI–RGO nanocomposites. The PANI composites with RGO were synthesized in the presence of dopant (dPANI–RGO) and without dopant (PANI–RGO). A comparative study was performed for RGO, PANI, dPANI, PANI–RGO and dPANI–RGO. The nanocomposites were characterized by XRD, FESEM, FTIR and TGA. XRD study showed that the dPANI–RGO is more crystalline in nature. The FESEM studies revealed that longer polyaniline nanotubes can be obtained on RGO sheets in the presence of RGO with HNO3. FTIR results show a greater extent of formation of quinoid units in the presence of both HNO3 and RGO, while benzenoid units show this effect only with HNO3. TGA results showed successful incorporation of RGO sheets with the enhanced thermal stability of dPANI–RGO as compared to dPANI. The electrochemical behavior of dPANI–RGO was also investigated. In the presence of RGO and HNO3, longer polyaniline nanotubes grow on RGO sheets forming a continuous network for electron transfer resulting in low charge transfer resistance for dPANI–RGO (3 Ω) as compared to PANI (29 Ω), which ultimately improves the electrochemical performance of the nanocomposites as a supercapacitor electrode material. The dPANI–RGO nanorods exhibited a specific capacitance of 563 F/g and good cycling stability up to the 5000 cycles with 84% specific retention at 0.5 A g−1.

Reduced graphene oxide/polypyrrole/nitrate reductase deposited glassy carbon electrode (GCE/RGO/PPy/NR): biosensor for the detection of nitrate in wastewater

In the present work, a novel biosensor (GCE/RGO/PPy/NR) based on the nanocomposite of reduced graphene oxide (RGO), polypyrrole (PPy) immobilized by nitrate reductase (NR) was developed on a glassy carbon electrode (GCE). The conductive nanocomposite (RGO/PPy) was synthesized by in situ oxidative polymerization of pyrrole in the presence of RGO in acidic medium. A facile and green path was employed to synthesize RGO from graphene oxide (GO). This was performed by a novel route using Abelmoschus esculentus vegetable extract as a stabilizing and reducing agent for GO. The composite of reduced graphene oxide and polypyrrole (RGO/PPy) was deposited onto GCE with subsequent deposition of NR enzyme on the GCE/RGO/PPy to develop GCE/RGO/PPy/NR biosensor. The surface morphology and structural features of the composites were studied by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical behavior and electrocatalytic activity of the biosensor were examined by cyclic voltammetry at different scan rates (20–100 mV s−1) in the synthetic nitrate solution. The developed bio-anode achieved a maximum current density of 4.24 mA cm−2 at a scan rate of 100 mV s−1 for 10 mM sodium nitrate solution.

Electrochemical study on an activated carbon cloth modified by cyclic voltammetry with polypyrrole/anthraquinone sulfonate and reduced graphene oxide as electrode for energy storage

This work describes a two-step procedure for the electrochemical coating of reduced graphene oxide (RGO) and polypyrrole anthraquinone sulfonate (PPyAQS) onto an activated carbon cloth (ACC) by cyclic voltammetry (CV). The textile samples were characterized by CV, electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge measurements using a sandwich-type (electrode/separator/electrode) cell designed to operate in three or two-electrode configurations. The presence of RGO onto the ACC surface optimized the electrosynthesis of PPyAQS and reinforced the stability of the polymer with the number of charge/discharge cycles. A retention capacity of 90% after 100 charge-discharge cycles together with an energy density of 7.8 × 10−4 W h cm−2 at a power density of 1.8 × 10−3 W cm−2 were obtained for the ACC/RGO/PPyAQS sample. The analyses by field emission scanning electron microscopy (FESEM) showed the RGO veils-like and PPyAQS glomerular structures covering the ACC-fibers. The Fourier transform infrared spectroscopy (FTIR) analyses not only detected the presence of PPy and AQS, but also, the changes in the molecular structure of PPyAQS, depending on its oxidation state, as consequence of the redox reactions occurred in the charge/discharge processes in the two-electrode cell.

Optimum Preferential Oxidation Performance of CeO2–CuOx–RGO Composites through Interfacial Regulation

Interfacial regulation offers a promising route to rationally and effectively design advanced materials for CO preferential oxidation. Herein, we initiated an interfacial regulation of CeO2-CuO x-RGO composites by adjusting the addition sequence of the components during the support formation. The presence of RGO along with the sequence tuning of the components is confirmed to survey the changes of the oxidation state of copper species, the content and distribution of the Cu+ site, and the synergistic interactions between Cu-Ce mixed oxides and reduced graphene oxide (RGO) over the catalysts. These catalysts were systematically characterized by inductively coupled plasma, X-ray diffraction, transmission electron microscopy/high-resolution transmission electron microscopy, hydrogen temperature-programmed reduction, X-ray photoelectron spectra, thermal gravimetric analysis, Raman spectra, and in situ diffuse reflectance infrared Fourier transform spectroscopy measurements. The results show that RGO is favorable for the generation of Cu+ and the dispersion of copper-cerium species in the as-prepared catalysts. Furthermore, by multi-interfacial regulation of the CeO2-CuO x-RGO composites, the catalyst CeO2/CuO x-RGO exhibits a strikingly high catalytic oxidation activity at a low temperature coupled with a broader operation temperature window (i.e., CO conversion >99.0%, 140-220 °C) in the CO-selective oxidation reaction, which has been attributed to the high content of the active species Cu+ enriched on the surface, the highly dispersed copper oxide clusters subjected to a strong interaction with ceria, and the synergistic interactions between Cu-Ce mixed oxides and RGO.

Study of the NO2 sensing mechanism of PEDOT-RGO film using in situ Raman Spectroscopy

In this work, the mechanism of the NO2 reaction with PEDOT-RGO composite film has been investigated via in situ Raman spectroscopy. Reduced graphene oxide (RGO), poly(3,4-ethylenedioxytiophene)-reduced graphene oxide (PEDOT-RGO) and poly(3,4-ethylenedioxytiophene)/ClO4− (PEDOT/ClO4−) films were fabricated using an electrodeposition method and used as resistance sensors of gaseous nitrogen dioxide. The experimental results indicate that NO2 causes overoxidation of the PEDOT polymer (PEDOT/ClO4− film) which leads to resistance increase and irreversible response. In contrast, the PEDOT-RGO response in the presence of NO2 is reversible. During short NO2 exposure, PEDOT from the PEDOT-RGO composite does not react to the gas but the presence of RGO in the PEDOT-RGO composite does not affect the overoxidation potential. It was found that the nitrogen dioxide reacts more readily to reduced graphene oxide, thus RGO “protects” the polymer against the adverse overoxidation process.

A detailed investigation on the performance of dye-sensitized solar cells based on reduced graphene oxide-doped TiO2 photoanode

The sintered TiO2 nanofilms were immersed in the aqueous solution of graphite oxide and then were thermally reduced to reduced graphene oxide (RGO), resulting in RGO-doped TiO2 photoanodes employed in the dye-sensitized solar cells (DSSCs). This preparation method for the reduced graphene oxide–TiO2 (RGO–TiO2) photoanode could avoid the loss of RGO during the sintering process. The presence of RGO in the photoanodes was confirmed using Raman analysis, scanning electron microscopy, transmission electron microscopy, and energy-dispersive spectrometer. The amount of RGO in photoanode was obtained by thermo-gravimetric analysis. Other techniques such as X-ray diffraction, Brunauer–Emmett–Teller, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the composite materials of RGO–TiO2. The J–V measurement of RGO–TiO2-based DSSCs showed that the best photoelectric conversion efficiency (η) of 6.85% is 11.7% higher than that of the pure TiO2 (P25–TiO2)-based DSSCs. It was shown that RGO in the photoanode could facilitate the phase transition in TiO2 crystals (from anatase to rutile) resulting in the mixed crystals in the photoanodes. The existence of RGO and mixed-crystal structure of TiO2 changed the electronic transmission pathway, reduced the recombination rate of electron–hole pairs, and thus improved the η of DSSCs.

Preparation of a Reduced Graphene Oxide @ Stainless Steel Net Electrode and Its Application of Electrochemical Removal Pb(II)

A novel RGO@SSN electrode prepared by directly electrodepositing reduced graphene oxide (RGO) on stainless steel net (SSN) was applied to remove Pb(II) from the aqueous solution. The RGO@SSN electrode exhibits substantial apparent current densities and the presence of RGO on SSN affects the morphology of deposited crystal. After electrochemical treatment with RGO@SSN for 200 min, the Pb(II) removal efficiency of Pb(II) solution (1000 mg L−1) gets to 97.2%, which is promoted by 12.0% compared to that with the SSN treatment. The removal rate of RGO@SSN is 4.45 times higher than that of SSN. The polarization resistance is promoted by 55.3 and 89.5% in 0.1 M NaCl and 0.1 M HCl solution, respectively, indicating stronger protection against corrosion. Moreover, the RGO@SSN electrode can be efficiently recycled in dilute HNO3 solution. These results suggest that RGO@SSN electrode possesses a good potential to be applied for the treatment of Pb(II) in wastewater.