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Although the risk of graphene materials to aquatic organisms has drawn wide attention, the combined effects of graphene materials with other contaminants such as toxic metals, which may bring about more serious effects than graphene materials alone, have seldom been explored. Herein, the effects of graphene (GN) and graphene oxide (GO, an important oxidized derivative of graphene) on copper (Cu) toxicity to Daphnia magna were systematically investigated. The results indicated that GN remarkably increased the Cu accumulation in D. magna and enhanced the oxidative stress injury caused by Cu, whereas did not significantly alter D. magna acute mortality within the tested Cu concentrations (0–200 μg L −1 ). On the contrary, GO significantly decreased the Cu accumulation in D. magna and alleviated the oxidative stress injury caused by Cu. Meanwhile, the presence of GO significantly reduced the mortality of D. magna when Cu concentration exceeded 50 μg L −1 . The different effects of GN and GO on Cu toxicity were possibly dependent on the action of surface oxygenic functional group. Because of the introduction of surface oxygenic functional groups, the adsorption ability to metal ions, stability in water and interaction mode with organisms of GO are quite different from that of GN, causing different effects on Cu toxicity. This study provides important information on the bioavailability and toxicity of heavy metals as affected by graphene materials in natural water. [ABSTRACT FROM AUTHOR] more...

A new hierarchical nanoarchitecture with integration of multiple active materials has been developed for highly efficient hydrogen evolution reaction (HER), by decorating a perpendicular hybrid of MoS2 and N-doped graphene nanosheets with CdS nanoparticles. The unique architecture promoted light trapping and absorption for highly efficient light harvesting and photocarrier generation, and offered an unblocked electron transport pathway for rapid charge separation/transport to suppress charge recombination. Its high surface area and high density of active sites result in highly efficient utilization of photogenerated carriers for productive HER. Significantly, without using noble metals as co-catalysts, the photocatalysts demonstrated rapid HER rates as high as 5.01 mmol h−1 g−1 under visible-light irradiation, which was approximately 25 times that of pure CdS. The hydrogen production remained stable after a continued test for 30 h, showing an exceedingly high performance and superior stability. [ABSTRACT FROM AUTHOR] more...

Reduced graphene oxide (rGO) is a promising support material for nanosized electrocatalysts. However, the conventional stacking arrangement of rGO sheets confines the electrocatalysts between rGO layers, which decreases the number of catalytic sites substantially. We report here a facile synthesis of vertically oriented reduced graphene oxide (VrGO) through cyclic voltammetric electrolysis of graphene oxide (GO) in the presence of Na2PdCl4. Experiments without Pd nanoparticles or with a low loading amount of Pd nanoparticles results in the deposition of rGO parallel to the electrodes. The vertical orientation of Pd/rGO nanoflakes causes a remarkable enhancement of the catalytic activity toward methanol electro-oxidation. The mass activity (620.1 A gPd−1) of Pd/VrGO is 1.9 and 6.2 times that of Pd/flat-lying rGO (331.8 A gPd−1) and commercial Pd/C (100.5 A gPd−1), respectively. Furthermore, the Pd/VrGO catalyst shows excellent resistance to CO poisoning. This work provides a simple wet-chemical method for VrGO preparation. [ABSTRACT FROM AUTHOR] more...

We report on a highly sensitive and selective electrochemiluminescence (ECL) based method for the determination of pentachlorophenol (PCP). It is based on a new hybrid material composed of CdS quantum dots (QDs), graphene, and carbon nanotubes (CNTs), and uses peroxodisulfate as the coreactant. The use of this system results in a nearly 18-fold increase in ECL intensity. On interaction between PCP and the QDs, a decrease in ECL intensity is observed at PCP in a concentration as low as 1.0 pM and over a wide linear range (from 1.0 pM to 1.0 nM). The method is hardly affected by other chlorophenols and nitrophenols, and the electrode can be recycled. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR] more...

Pentachlorophenol (PCP) is an environmental pollutant of serious concern due to its high toxicity and long persistence property. Fast and sensitive detection of PCP is therefore of great interest. Here, for the first time, a novel electrochemiluminescence (ECL) sensor based on Au nanoclusters/graphene (Au NCs/GR) hybrid has been constructed for the detection of PCP, with S2O8 2− as coreactant. GR facilitates both Au− and SO4 − production, and a high yield of the excited Au NCs (Au*+) produces due to the presence of Au– and SO4 −. The interaction between PCP and the Au*+ results in a sensitive change in the ECL intensity, with an unprecedented sensitivity reaching 1.0×10−14 M concentration in a wide linear range from 1.0×10−14 M to 1.0×10−10 M. Other compounds which cannot be oxidized by the Au*+ show little interference on the detection of PCP. The obtained ECL sensor is low toxicity and regenerable, furthermore, the practicability of the ECL sensor in real water sample is also tested, which shows satisfactory results. [ABSTRACT FROM AUTHOR] more...

We have modified a glassy carbon electrode by single-step electrodeposition of graphene (GR), gold nanoparticles (AgNPs), and chitosan (CS) directly from a solution containing graphene oxide, tetrachloroauric acid, and chitosan. The surface and electrochemical properties of the film-modified electrode were investigated by SEM and TEM images. The AuNPs have a diameter of about 20 nm and are uniformly dispersed in the matrix. Combining the advantages of GR (i.e., high surface area and conductivity), of AuNPs (excellent electrical conductivity) and CS (excellent film-forming ability and good water permeability), the hybrid film effectively enhances electron-transfer and promotes the response to lead(II) ion. Under the optimum conditions, a linear relationship exists between electrical current and the concentration of lead (II) ion in the range between 0.5 to 100 μg L-1, with a detection limit of 1 ng L-1 (at an SNR of 3). The electrode was successfully applied to the detection of lead(II) in spiked samples of river water. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR] more...

We have electrodeposited a composite film consisting of graphene oxide, chitosan and glucose oxidase directly on a glassy carbon electrode (GCE) through electrochemical reduction of a solution of the 3 components under controlled direct electrical potential. The procedure takes only several minutes, and the thickness of the resulting film is uniform and controllable. The GOx has uncompromised bioactivity and exhibits reversible 2-proton and 2-electron transfer in presence of glucose. It therefore can be used amperometric sensing of glucose. The biosensor has a fast response (<3 s), a detection limit of 0.4 μM (which is 50-fold lower compared to the biosensor prepared by drop-casting solutions of the same materials onto an GCE), and a linear response in the 0.4 μM to 2 mM concentration range (which again is much better than that of the biosensor prepared by the drop-casting method). Other features include high reproducibility, long-time storage stability, and satisfactory selectivity. We presume that the direct single-step electrodeposition of this nanocomposite offers a promising approach towards novel types of highly sensitive and stable electrochemical biosensors. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR] more...

Abstract: A new photocatalyst, Ag nanoparticles (NPs) and reduced graphene oxide (RGO) co-decorated TiO2 nanotube arrays (NTs) (Ag/RGO–TiO2 NTs), was designed and facilely produced by combining electrodeposition and photoreduction processes. The structures and properties of the photocatalysts were characterized. The ternary catalyst exhibited almost 100% photocatalytic removal efficiency of typical herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from water under simulated solar light irradiation. The photodegradation rate toward 2,4-D over Ag/RGO–TiO2 NTs is 11.3 times that over bare TiO2 NTs. After 10 successive cycles with 1600min of irradiation, Ag/RGO–TiO2 NTs maintained as high 2,4-D removal efficiency as 97.3% with excellent stability and easy recovery, which justifies the photocatalytic system a promising application for herbicide removal from water. [Copyright &y& Elsevier] more...

Herein, a chemically bonded BiOBr-graphene composite (BiOBr-RG) was prepared through a facile in situ solvothermal method in the presence of graphene oxide. Graphene oxide could be easily reduced to graphene under solvothermal conditions, and simultaneously BiOBr nanoplates with pure tetragonal phase were grown uniformly on the graphene surface. The structure and photoelectrochemical properties of the resulting materials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and impedance and photocurrent action measurements. The combination of BiOBr and graphene introduces some properties of graphene into the photocatalysis reaction, such as excellent conductivity, adsorptivity, and controllability. A remarkable threefold enhancement in the degradation of rhodamine B (RhB) was observed with as-prepared BiOBr-RG as compared with pure BiOBr under visible light ( λ>420 nm). The enhanced photocatalytic activity could be attributed to the great adsorptivity of dyes, the extended photoresponse range, the negative shift in the Fermi level of BiOBr-RG, and the high migration efficiency of photoinduced electrons, which may effectively suppress the charge recombination. [ABSTRACT FROM AUTHOR] more...

It is of great significance in exploring alternative catalysts to platinum (Pt)-based materials for oxygen reduction reaction (ORR), because this reaction is invariably involved in various fuel cells and metal-air batteries. We herein reported the nitrogen doped graphene nanosheets (NGNSs) with pore volume of as high as 3.42 m/g and investigated their potential application as ORR catalysts, it was demonstrated the NGNSs featured high activity, improved kinetics and excellent long-term stability for ORR. The NGNSs were successfully used as cathode catalysts of microbial fuel cells (MFCs) and performed even better than the commercial Pt/C (Pt 10%) catalysts at the maximum power output. [ABSTRACT FROM AUTHOR] more...

Abstract: This paper proposed a direct electrodeposition approach to synthesis of graphene–chitosan (GR–CS) composite onto glassy carbon electrode (GCE) under controlled potential. This direct electrodeposition approach for the construction of GR-based hybrid was environmentally friendly, which would not involve the chemical reduction of graphene oxide (GO) and therefore result in no further contamination. The whole procedure was simply and cost only several minutes. Moreover, Combining the advantages of GR (large surface-to-volume ratio and high conductivity) and CS (good biocompatibility and adsorption), the GR–CS composite could be highly efficient to capture OPs and used as solid phase extraction (SPE). The GR–CS/GCE was used to detect organophosphate pesticides (OPs), using methyl parathion (MP) as a model analyte. The significantly redox response of MP on the GR–CS/GCE was proved. The linear range was wide from 4.0ngmL−1 to 400ngmL−1, and a low detection limit of 0.8ngmL−1 for MP was achieved. Moreover, the proposed sensor exhibited high reproducibility, long-time storage stability and satisfactory anti-interference ability. The proposed GR–CS/GCE opens new opportunity for green, fast, simple, and sensitive analysis of OP compounds. [Copyright &y& Elsevier] more...

Highlights: [•] RGO/CuInS2–TiO2 NTs was facilely fabricated by electrodeposition technique. [•] The new catalyst exhibited significantly photocatalytic activity. [•] Refractory herbicide 2,4-D was efficiently photocatalytically degraded. [Copyright &y& Elsevier] more...

Abstract Bulk adsorbents for fast and deep removal of arsenic in water is highly demanded for practical treatment process, especially fixed-bed column process. In this study, a superior bulk adsorbent of porous Fe 2 O 3 nanocubes-impregnated porous graphene aerogel (PGA/P Fe 2 O 3) is prepared using a simple template engineering. The maximum capacity for As(III) and As(V) reaches as high as 172.27 and 217.34 mg g−1 of Fe 2 O 3 , respectively. The adsorption equilibrium times of As(III) and As(V) on PGA/P Fe 2 O 3 are only 30 and 5 min, respectively (m / V = 0.5 g L−1, C 0 = 5 mg L−1). Significantly, the high concentrations of As(III) and As(V) can be reduced below 10 μg L−1 within only 60 and 5 min, respectively. The aerogel is conducive to fast diffusion of arsenic and porous Fe 2 O 3 nanocubes provide abundant adsorption sites. Moreover, the adsorbent exhibits an outstanding reusability. The adsorbent also shows a strong anti-interference to aquatic environment. A real realgar tailing wastewater (C 0 = 3.076 mg L−1 for As(III) and 3.225 mg L−1 for As(V)) can be deep treated (below 10 μg L−1) within 4 h (m / V = 0.6 g L−1). The bulk adsorbent of PGA/P Fe 2 O 3 presents a high column treatment capacity of arsenic-containing groundwater (4750 BV for As(III), 5730 BV for As(V)), producing only 12 BV eluent. This work develops a superior bulk adsorbent for large-scale treatment of arsenic-containing wastewater. Graphical abstract Image 1 Highlights • Ultrafast adsorption of arsenic by bulk porous Fe 2 O 3 -graphene aerogel. • Excellent recyclability and reusability. • High treatment capacity on fixed-bed column. • Efficient removal of arsenic from actual groundwater. [ABSTRACT FROM AUTHOR] more...

Highly active, durable and scalable fuel cell electrocatalysts are highly desirable but challenging. Herein, we first develop a novel catalyst of PtRu nanoalloys loaded on graphene modified anodic TiO 2 nanotubes arrays (TNTs) grown on flexible Ti wires (denoted as PtRu/RGO/TNTs). Electrodeposited reduced graphene oxide (RGO) is used to improve the electric conductivity and facilitate the dispersion of PtRu nanoparticles. TiO 2 nanotubes arrays could guarantee the large surface area, and PtRu nanoalloys are well-dispersed on the inner and external walls of the TNTs as well as the RGO surface, which could facilitate the fast mass transport and enhanced electrocatalytic activity. PtRu nanoalloys with intimate contact between the two metals is conductive to remove the harmful CO-like byproduct, resulting in superior tolerance to CO poisoning. In addition, this work first design and use the spirally flexible Ti wire electrode configuration in direct methanol fuel cell, which shows a highly efficient catalytic performance. Moreover, this kind of catalytic support is a strong candidate for other electrochemical energy conversion devices. [ABSTRACT FROM AUTHOR] more...

In this paper, g-C 3 N 4 /GR hybrid has been prepared by a novel one-step electrochemical reduction technology for the first time. GR not only serves as immobilization platform for g-C 3 N 4 , but also significantly enhances the electrochemiluminescence (ECL) signal of g-C 3 N 4 (∼4.7 times); additionally, the ECL signal can be further enhanced in the presence of the self-produced coreactant from oxygen reduction. Moreover, due to the quenching effect of pentachlorophenol (PCP) on the ECL signal of g-C 3 N 4 /GR, an advanced ECL sensor based on g-C 3 N 4 /GR has been fabricated for the ultrasensitive and rapid detection of PCP with unprecedented sensitivity reaching 1.0 × 10 −11 mol L −1 in a wide linear range from 1.0 × 10 −11 to 1.0 × 10 −7 mol L −1 , and the possible ECL detection mechanism has been proposed in detail. The practicability of the sensing platform in real water sample shows ideal recovery rates. Moreover, we also find that the one-step electrodeposition technology might be a good and viable way to make the bulk g-C 3 N 4 thinner. Our experiments display the powerful utility of GR to g-C 3 N 4 ECL studies and will emerge eximious applications in analytical communities and environmental monitoring. [ABSTRACT FROM AUTHOR] more...

Mesh of TiO 2 /graphene/Cu 2 O was fabricated by chemical vapor deposition of graphene following electrochemical deposition of Cu 2 O on anodized Ti soft wire bearing TiO 2 nanotubes. The mesh of TiO 2 /graphene/Cu 2 O was applied in photoelectrocatalytic oxidation of bisphenol A (BPA). The as-prepared TiO 2 /graphene/Cu 2 O mesh was used as both catalyst and electrode. Under visible light irradiation, BPA was effectively oxidized through photoelectrocatalysis over the TiO 2 /graphene/Cu 2 O mesh. Three main intermediates were evidenced during photoelectrocatalytic degradation of BPA, and no toxic products were determined. A detailed pathway of BPA degradation by TiO 2 /G/Cu 2 O is proposed based on the identified intermediates. [ABSTRACT FROM AUTHOR] more...

A poly(sodium acrylate)–graphene oxide (PSA–GO) double network hydrogel adsorbent was facilely prepared in mild conditions. The chemical composition of the hydrogel adsorbent was characterized by FITR, Raman spectra and XPS analysis. The uniaxial compression tests proved extraordinary mechanical strength of PSA–GO gel, benefiting to practical application. The PSA–GO hydrogel was used as an adsorbent for heavy metal ions such as Cd(II) and Mn(II). The adsorption behaviors in different conditions (e.g., pH, contact time, ionic concentration and existence of fulvic acid) as well as the adsorption mechanism were studied. The maximum sorption capacities were found up to 238.3 mg/g and 165.5 mg/g at pH = 6 and T = 303 K, for Cd(II) and Mn(II), respectively, estimating from the Langmuir model. After experiencing four cycles, this adsorbent kept high removal efficiencies of Cd(II) and Mn(II), indicating a good reusability. Cost analysis reveals that the adsorbent is relatively low-cost. Meanwhile, its satisfactory performance in practical industrial effluent test demonstrates that PSA–GO gel can be a potential candidate for practical application. [ABSTRACT FROM AUTHOR] more...

In this paper, 3-D graphene cross-linked with mesoporous MnS clusters (60–150nm), composed of many nanoparticles (10–20nm) and pores, was fabricated by a simple solvothermal method. As an anode material for lithium-ion batteries, the MnS/graphene nanocomposite exhibited high reversible capacity, good cycling performance and excellent rate capability. A specific capacity as high as 980mAhg−1 can be achieved at a current density of 50mAg−1 in the 30th cycle. [ABSTRACT FROM AUTHOR] more...

Abstract: A new photocatalyst, magnetic TiO2-graphene, was designed and facilely produced by combining sol–gel and assembling processes. Taking advantages of graphene and TiO2, the catalyst exhibited strong light absorption in the visible region and high adsorption capacity to organic pollutants, resulting in almost 100% photocatalytic removal efficiency of typical herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from water under simulated solar light irradiation, far higher than 33% on commercial P25. Toxicity assessment indicates the total decomposition of the original substrate. Furthermore, the catalyst can be rapidly recovered with highly stable photocatalytic performance. After 8 successive cycles, the removal efficiency of 2,4-D maintained 97.7%, and particularly, 99.1% 2,4-D removal efficiency came back at the ninth recycle when the catalyst was re-treated by ultrasonication. Moreover, even after being laid aside for one year the catalyst still kept the 2,4-D removal efficiency as high as 95.6%. For practical application, the photocatalytic also demonstrated high removal efficiencies of herbicide 2,4-D. The photocatalyst is a promising platform for removing herbicide pollutants from water. [Copyright &y& Elsevier] more...

Abstract: Hydrated zirconium oxide (ZrO(OH)2) nanoparticles were modified with graphite oxide (GO) (denoted herein as GO–ZrO(OH)2) by hydro-thermal co-precipitation reaction, and were used for the simultaneous removal of As(III) and As(V) from drinking water. The GO–ZrO(OH)2 nanocomposites were characterized using Fourier transformer infrared spectroscopy, X-ray diffraction analysis, high resolution transmission electron microscopy, Zeta-potential, and specific surface area analysis. The size of ZrO(OH)2 particles in GO–ZrO(OH)2 is below 5nm, and the specific surface area of GO–ZrO(OH)2 is about 4 times that of ZrO(OH)2 nanoparticles. The GO–ZrO(OH)2 nanocomposites showed high adsorption capacity in a wide pH range, and the monolayer adsorption amounts calculated based on the Langmuir adsorption model were 95.15 and 84.89mg/g for As(III) and As(V), respectively, which are 3.54 and 4.64 times that of ZrO(OH)2 nanoparticles. The high adsorption capacity is attributed to good dispersion of ZrO(OH)2 nanoparticles in the GO substrate. The GO–ZrO(OH)2 nanocomposites can simultaneously remove As(III) and As(V) in water. Moreover, GO–ZrO(OH)2 showed good anti-interference ability to co-existing anions, and exhibited excellent recyclability. The experimental results suggest that GO–ZrO(OH)2 is a promising adsorbent for the removal of arsenic from drinking water. [Copyright &y& Elsevier] more...

Abstract: Graphene film was formed on the surface of titanium dioxide nanotube (TiO2 NT) arrays through in situ electrochemical reduction of a graphene oxide dispersion by cyclic voltammetry. The residual oxygen-containing groups and other structural defects such as sp3-hybridized carbons in the electrodeposited graphene were further removed by photo-assisted reduction of the underlying TiO2 NTs, thus achieving the maximum restoration of π-conjugation in the graphene planes. Spectroscopic, electrochemical, and photoelectrochemical techniques were used to characterize the graphene films, and the use of the resulting graphene–TiO2 NT material in photocatalysis was investigated. The results showed that the graphene–TiO2 NT material exhibited a greatly improved photocatalytic activity compared with unmodified TiO2 NTs. [Copyright &y& Elsevier] more...

Abstract: Graphene nanosheets were directly deposited onto a glassy carbon electrode through cyclic voltammetric reduction of a graphene oxide colloidal solution. The resulting electrodes were characterized by electrochemical methods and scanning electron microscopy. The application of the graphene modified electrodes in simultaneous determination of hydroquinone and catechol was investigated. [Copyright &y& Elsevier] more...

Bioelectrochemical systems (BESs) possess a great potential for simultaneous wastewater treatment and energy recovery. Rational construction of electrode materials could significantly improve the BESs performance. Three-dimensional macroporous electrode interface with high conductivity is highly desirable but challenging. In this work, we report a hierarchically nanostructured reduced graphene oxide nanosheets-polypyrrole (rGO@PPy) electrode via one-step electrodeposition technique. The prepared electrode was comprehensively studied by scanning/transmission electron microscopy, Raman spectroscopy, X-ray diffraction and electrochemical measurements, which showed that the rGO@PPy possessed a three-dimensional macroporous interconnecting scaffold with superior conductivity. The rGO@PPy electrode was utilized in Geobacter sulfurreducens inoculated BESs, and the maximum current density was 4.10 ± 0.02 mA cm−2, which is 8-fold higher than that of a rGO electrode (0.51 ± 0.03 mA cm−2), and is among the best performance reported for two-dimensional electrodes. The improved performance is ascribed to ultrahigh biomass concentration induced by "best match scale" between rGO@PPy and microbes, excellent extracellular electron transfer, as well as enhanced microbial affinity through the adequate exposure of biocompatible PPy layers. This work demonstrated a synergistic effect between rGO and PPy for the BESs performance improvement, and provided a new insight to design and fabricate a high-performance bioelectrode. • A novel hierarchically porous rGO@PPy electrode was fabricated for use in BESs. • Optimum size matching was achieved between electrode materials and microbes. • High rGO@PPy bioelectrode conductivity and good biocompatibility realized. • The rGO@PPy bio-electrode achieved the highest current density reported to date. • The rGO@PPy synthesis method is facile, cost-effective and environmentally friendly. [ABSTRACT FROM AUTHOR] more...