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In this study, we reported a novel type-I heterojunction between red phosphorus and graphitic carbon nitride under vacuum condition, which is a novel synthesis process. For preparing the red phosphorus composites, the vacuum condition is appropriate to prevent it from self-ignition. The prepared materials were analyzed with different analytic techniques for the confirmation of their heterojunctions and structure formation. The introduction of red phosphorus into graphitic carbon nitride, reduce the structural defects and increase the charge separation ability. After medication, the synthesized composite shows an enhanced photocatalytic activity against acute toxicity category-III non-color (MTSM, Metsulfuron methyl) and color (RhB), organic pollutants. The photocatalytic degradation mechanism (Mott-Schottky and VB-XPS) study reveal that red phosphorus /graphitic carbon nitride possess type-I heterojunction with enhanced catalytic behavior, due to the effective transformation of photo-generated electrons from CB of GCN to CB of RP with the help of heterojunctions and due to unmoved photo holes on VBs. Synthesized composites also maintained their performance after reused them in three cyclic form. [ABSTRACT FROM AUTHOR]

The vacuum tube method has been used for the construction of nondestructive and physically stable graphitic carbon nitride/graphene nanoplatelet composites and their photocatalytic behavior studied by measuring different photoactivities, such as photocurrent, photoluminescence, and the photodegradation of tetracycline hydrochloride under visible‐light irradiation. The formation of a heterojunction was confirmed by XRD, TEM, SEM, FTIR, XPS, and Raman spectroscopy. The results of this research indicate that the vacuum tube method is a facile, economic, and environmentally friendly approach to the preparation of composites. An ion‐trapping experiment indicated that, under visible light, the most effective photocatalyst generated the superoxide radical (O2·–) and holes (h+) to achieve the complete degradation of tetracycline hydrochloride. [ABSTRACT FROM AUTHOR]

A novel electrochemical sensor based on nitrogen doped graphene (NGE) and palygorskite (Pal) for the simultaneous detection of hydroquinone (HQ) and catechol (CT) has been proposed. Pal is particularly pointed out for its appreciable specific surface area and reactive-OH groups on its surface. Acid treatment Pal demonstrated better physico-chemical properties, which are propitious to electrochemical sensor construction. The introduction of NGE not only improved the poor conductivity of Pal but also served as an excellent adherent matrix. The modified electrode demonstrated the enhanced redox peak currents of HQ and CT with good discrimination. Under optimized conditions, the linear ranges for HQ and CT were 2–50 μM and 1–50 μM, with detection limit (LOD) of 0.8 μM and 0.13 μM, respectively. The result designates that the Pal/NGE composite promises to be a new eco-friendly modified material for sensor fabrication. [ABSTRACT FROM AUTHOR]

This work reports the synthesis of a novel 3D porous graphene (PG) from maleic acid (HO 2 CCH=CHCO 2 H) used as a carbon source through a simple one-step carbonization process. The sodium carbonate (Na 2 CO 3) was used as the skeletal substrate for 3D PG preparation and we observed that the ideal mass ratio of maleic acid (MA) to Na 2 CO 3 is 1:4, which gives the highest yield and net carbon content for 3D PG preparation. The Na 2 CO 3 decomposition temperature is greater than 550 °C which causes the release of CO 2 and hence ultimately it produced 3D porous graphene (PG). The prepared 3D PG was characterized by X-Ray Diffraction (XRD), Raman Spectra, Transmission Electron Microscope (HRTEM), Scanning Electron Microscope (SEM), X-Ray Photoelectron Spectroscopy (XPS), and Brunauer Emmett Teller (BET) Surface area. The synthesized 3D architectural frameworks of graphene offered well-defined pores with a large surface area amounting to 567.56 cm2g-1. However, with increasing temperature above 700 °C, there is a decrease in surface area which can be attributed to the heat shrinkage and sintering or collapse of smaller diameter pores. Also at higher temperatures, Na 2 CO 3 decomposes quickly which impart less effect on the morphology of synthesized graphene. In addition, electrochemical and adsorptive properties were also studied and a comparison is made with 3D rGO synthesized separately. The unique porous structure of 3D PG showed an excellent adsorption capacity of 433.3 (mg g-1) towards emerging pharmaceutical compound Atenolol and it further increases up to 642.4 (mg g-1) towards organic dye Rhodamine B, which is much higher than the 3D reduced graphene oxide rGO obtained by the chemical reduction process. Similarly, the as-synthesized 3D PG depicted enhanced oxidation and reduction properties as compared to 3D rGO as is evident from sharp anodic and cathodic peaks for the 3D PG prepared at 700 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • Green activation-self-activation strategy was proposed to prepare GO-inbuilt ENHPCs. • The splendid SAC of 17.86 mg/g and rapid ASAR of 0.99 mg/g/min for Ni2+ were gained. • The potential for eliminating NaCl, MgCl 2 , CaCl 2 and Ni2+ wastewater was evaluated. • Micro-mesoporous structure and copious active sites accelerated ion removal. Capacitive deionization (CDI) is considered a polar-promising technology to remove heavy-metal ions from wastewater. Herein, a green activation-self-activation strategy was exploited to build graphene (GO)-inbuilt mesopore-dominated N-doped hierarchical porous carbons (ENHPCs) using sodium lignosulfonate (SLS) as carbon sources/self-activators. Different from SLS self-activation and K 2 C 2 O 4 -SLS activation-self-activation, ENHPC LKG gained via GO-mediated K 2 C 2 O 4 -SLS activation-self-activation showed suitable mesopore-dominated micro-mesoporous structures with high surface area of 1795.5 m2/g, large mesoporous volume of 0.87 m3/g, 3.65 % N-doping and excellent conductivity. Its unique hierarchical porous structure and abundant active sites facilitated the ion rapid insertion and extraction. When utilized to capture low-concentration nickel (Ni2+) ions, ENHPC LKG delivered splendid salt removal capacity of 17.86 mg/g, rapid average salt removal rate of 0.99 mg/g/min and standout cycle stability. Meanwhile, ENHPC LKG was further extended to remove NaCl, MgCl 2 , CaCl 2 and Ni-containing wastewater, showing superior CDI property. Moreover, the recycled ENHPC LKG (10th) taken to eliminate indomethacin (IDM) depicted a splendid adsorption capacity. This work proved the significant applicant potential of the novel and green ENHPC LKG for disposing of Ni2+ ions via CDI technology. [ABSTRACT FROM AUTHOR]

Polypyrrole-grafted nitrogen-doped graphene (PPY-g-NGE) was successfully synthesized by simultaneous modification of graphene through nitrogen doping and polymeric grafting, and used for the detection of paraquat (PQ). The chemical structure, morphology and interaction of the obtained PPY-g-NGE were verified by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The PPY-g-NGE modified glassy carbon electrode (GCE) was fabricated to investigate its electrochemical behavior and sensitive detection of PQ by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that the novel PPY-g-NGE modified GCE exhibited excellent electrochemical performance and electrocatalytic activity to the redox reaction of PQ, with comparison to NGE and non-grafted composite of PPY-NGE. The two reduction DPV peaks of PQ at −0.60 V and −1.00 V were significantly enhanced at the PPY-g-NGE modified electrode. Under the optimized condition, the reduction peak currents of PQ at the PPY-g-NGE modified electrode were linear over the concentration range from 5.00 × 10 −8 to 2.00 × 10 −6 M with detection limits of 41 nM and 58 nM for Peak 1 and Peak 2, respectively. Besides the good sensitivity, the sensor also exhibited fine stability and strong anti-interference ability due to the well-combination and synergistic effect of polypyrrole and nitrogen doped graphene. [ABSTRACT FROM AUTHOR]

A simple and sensitive label-free electrochemical biosensor for nimodipine was fabricated by using nitrogen-doped graphene (NGE) modified electrode. The surface morphology and electron transfer behavior of the modified electrodes were studied by scanning electron microscopy and electrochemical impedance spectroscopy, respectively. The electrochemical behaviors of nimodipine at the modified electrodes were investigated by using cyclic voltammetry. On the basis of the excellent electrocatalytic activity of NGE, an obvious cathodic peak of nimodipine could be caused at the NGE modified glassy carbon electrode (GCE), moreover, the electrochemical signal was greatly enhanced compared with the undoped graphene modified GCE. Under the optimized conditions, the present sensor showed excellent performances for nimodipine detection including wide linear range of 0.02–3 μM, low detection limit (9.1 nM), good selectivity to the general coexisted interferences, etc. The proposed biosensor was also successfully applied to validate its capability for the analysis of nimodipine in tablets. The work would promote the potential application of NGE as an excellent material in fabricating electrochemical sensors for chemical or biochemical analysis. [ABSTRACT FROM AUTHOR]

Poly(3-methylthiophene)/nitrogen doped graphene modified glassy carbon electrode (P3MT/NGE/GCE) was prepared through simple drop-casting of NGE, followed by the electrodeposition of P3MT film for sensitive electrochemical determination of trace amounts of pesticide phoxim. The morphology and structure of P3MT/NGE/GCE were characterized by scanning electron microscopy; the electrochemical behavior of P3MT/NGE/GCE was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and chronocoulometry. The preparation conditions of modified electrode, the dropping amount of NGE and polymerization laps of P3MT, were optimized. Under the optimized conditions, the reduction peak current of cyclic voltammetric curve varied linearly with the concentration of phoxim over the two linear ranges of 0.02–0.2 μM and 0.2–2.0 μM, and the low detection limit was 6.4 nM according to lower linear range (S/N = 3). The sensor also exhibited excellent selectivity to phoxim over a wide range of possible interferents including ions, biomolecules, common environment pollutants and widely-used organophosphate pesticides. Moreover, the satisfactory practical feasibility of the sensor was evaluated by the environmental phoxim measurements. [ABSTRACT FROM AUTHOR]

Highlights: [•] PEDOT/NGE modified electrode was fabricated via CV method using nitrogen-doped graphene (NGE) coated GCE. [•] Highly reversible and well-separated redox couples of hydroquinone (HQ) and catechol (CT) were obtained at PEDOT/NGE/GCE. [•] A facile electrochemical sensor based on PEDOT/NGE/GCE was developed for simultaneous detection of HQ and CT. [Copyright &y& Elsevier]

Abstract: A novel poly(3,4-ethylenedioxy-thiophene) (PEDOT)/graphene oxide (GO) hybrid film was directly electrodeposited on a glassy carbon electrode. The SEM and TEM images of the as-obtained film revealed that PEDOT grew well on the surface of GO sheets with high affinity. The chemical structure of the composite was characterized by FT-IR, and the result conformed the formation of PEDOT doped by GO, leading to the enhanced electrochemical performance of the modified electrode. The composite modified electrode was utilized as an electrochemical sensor for the simultaneous detection of hydroquinone (HQ) and catechol (CT). It showed well electrocatalytic activity toward the redox of HQ and CT. Under the optimized condition, the response peak currents of the modified electrodes were linear over ranges from 2.5 to 200μM for HQ and from 2 to 400μM for CT. The sensor also exhibited good sensitivity with the detection limit of 1.6μM for both HQ and CT, and good stability. This study provides a new kind of composite modified electrode for electrochemical sensors. [Copyright &y& Elsevier]

Mesoporous CuS nanospheres (CuS-NS) decorated reduced graphene oxide (rGO) aerogel composite (3D CuS-NS/rGO) was prepared by chemical reduction process and used for the synergistic removal of Cr(VI) and cationic dyes. The porosity of the as prepared samples was determined by Bruner-Emmet-Teller (BET) surface Area. Structural and morphological properties were studied by Scanning electron microscopy (SEM) and Transmission electron microscope (TEM). These analysis revealed that the as obtained hybrid CuS-NS/rGO composite with three dimensional (3D) structure was composed of mesoporous CuS nanospheres clearly induced onto the interconnected network of rGO sheets. The photocatalytic performance of 3D CuS-NS/rGO composites was studied against the reduction of Cr(VI) and degradation of cationic dyes (MB and RhB) under visible light spectrum. Excellent photocatalytic performance was observed with 3D CuS/rGO hybrid composites as compared to the as prepared CuS nanospheres. This high photocatalytic activity was attributed to the efficient charge transfer from the mesoporous CuS nanospheres to nanosheets of rGO, which was confirmed by UV–Vis spectrometry (UV–Vis). Electrical conductivity of the prepared samples was also investigated using electrochemical impedance spectroscopy (EIS). Additionally, the as prepared hybrid composites was easy to recycle by using simple tweezers and can be a best candidate for industrial applications. Image 1 • Preparation of 3D CuS/rGO aerogel by simple reduction process. • Photocatalytic activity of 3D CuS-NS/rGO investigated over Cr(VI) and cationic dyes. • Investigation of the catalyst concentration on photocatalytic performance. • High stability of 3D CuS-NS/rGO aerogel over five cycles. [ABSTRACT FROM AUTHOR]