PDDA-functionalized Graphene Research Articles

Electrodeposition of PtNPs on the LBL assembled multilayer films of (PDDA-GS/PEDOT:PSS)nand their electrocatalytic activity toward methanol oxidation

In the present work, PDDA-functionalized graphene sheets (PDDA-GS) were prepared by reduction with hydrazine hydratein situin the presence of poly(diallyldimethylammonium chloride) (PDDA).

A highly selective electrochemical sensor for 4-chlorophenol determination based on molecularly imprinted polymer and PDDA-functionalized graphene

Molecularly imprinted polymer (MIP) of 4-chlorophenol (4-CP) was synthesized and combined with poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (PDDA-G) to develop an electrochemical sensor for selective determination of 4-CP. The chemical structures of the imprinted films were analyzed using Fourier transform infrared (FTIR) spectroscopy. The morphology and interfacial behavior of MIP and PDDA-G modified glassy carbon electrodes (GCEs) were investigated by scanning electron microscopic (SEM) and electrochemical impedance spectroscopic (EIS) techniques, respectively. The obtained MIP/PDDA-G/GCE showed high sensing performance towards 4-CP. Under optimized conditions, the sensor showed a linear response to the concentration of 4-CP in a wide range from 0.8 to 100μmolL−1 with a detection limit (3S/N) of 0.3μmolL−1. Moreover, the imprinted sensor exhibited excellent specific recognition ability to 4-CP which could avoid the interference of other structurally similar phenolic compounds. The developed sensor was successfully applied to the detection of 4-CP in real-life water samples.

Ultra-sensitive film sensor based on Al2O3-Au nanoparticles supported on PDDA-functionalized graphene for the determination of acetaminophen.

An electrochemical sensor of acetaminophen based on poly(diallyldimethylammonium chloride) (PDDA)-functionalized reduced graphene-loaded Al2O3-Au nanoparticles coated onto glassy carbon electrode (Al2O3-Au/PDDA/reduced graphene oxide (rGO)/glass carbon electrode (GCE)) were prepared by layer self-assembly technique. The as-prepared electrode-modified materials were characterized by scanning electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. The electrocatalytic performances of Al2O3-Au/PDDA/rGO-modified glassy carbon electrode toward the acetaminophen were investigated by cyclic voltammetry and differential pulse voltammetry. The modified electrodes of graphene oxide (GO)/GCE, PDDA/rGO/GCE, and Al2O3-Au/PDDA/rGO/GCE were constructed for comparison and learning the catalytic mechanism. The research showed Al2O3-Au/PDDA/rGO/GCE having good electrochemical performance, attributing to the synergetic effect thatcomes from the special nanocomposite structure and physicochemical properties of Al2O3-Au nanoparticles and graphene. A low detection limit of 6nM (S/N = 3) and a wide linear detection range from 0.02 to 200μM (R (2) = 0.9970) was obtained. The preparation of sensor was successfully applied for the detection of acetaminophen in commercial pharmaceutical pills. Graphical abstract Schematic diagram of synthesis of Al2O3-Au/PDDA/rGO/GCE.

Sensitive and selective detection of Hg2+based on an electrochemical platform of PDDA functionalized rGO and glutaraldehyde cross-linked chitosan composite film

In this paper, a uniform PDDA-functionalized graphene composite film (GA–CS@PDDA-rGO) was utilized for detection of trace Hg2+by using glutaraldehyde cross-linked chitosan (GA–CS) as a Hg2+-chelating adsorbent and film-forming agent.

Pd-nanoparticle-supported, PDDA-functionalized graphene as a promising catalyst for alcohol oxidation.

Poly(diallyldimethylammonium chloride) (PDDA) has been employed as a modifying material for the development of new functional materials; then, the functionalized graphene was employed as a support for Pd nanoparticles through a facile method. The structures and morphologies of the as-synthesized Pd/PDDA-graphene composites were extensively characterized by Raman spectroscopy, XRD, XPS, and TEM. Morphological observation showed that Pd NPs with average diameters of 4.4 nm were evenly deposited over the functionalized graphene sheets. Moreover, the electrochemical experiments indicated that the Pd/PDDA-graphene catalyst showed improved electrocatalytic activity toward alcohol-oxidation reactions compared to the Pd/graphene and commercial Pd/C systems, as well as previously reported Pd-based catalysts. This study demonstrates the great potential of PDDA-functionalized graphene as a support for the development of metal-graphene nanocomposites for important applications in fuel cells.

Aptasensor for electrochemical sensing of angiogenin based on electrode modified by cationic polyelectrolyte-functionalized graphene/gold nanoparticles composites

Herein, a label-free and highly sensitive electrochemical aptasensor for the detection of angiogenin was proposed based on a conformational change of aptamer and amplification by poly(diallyldimethyl ammonium chloride) (PDDA)-functionalized graphene/gold nanoparticles (AuNPs) composites-modified electrode. PDDA-functionalized graphene (P-GR) nanosheets as the building block in the self-assembly of GR nanosheets/AuNPs heterostructure enhanced the electrochemical detection performance. The electrochemical aptasensor has an extraordinarily sensitive response to angiogenin in a linear range from 0.1pM to 5nM with a detection limit of 0.064pM. The developed sensor provides a promising strategy for the cancer diagnosis in medical application in the future.

An electrochemical sensor based on polyelectrolyte-functionalized graphene for detection of 4-nitrophenol

A novel electrochemical sensor based on poly(diallyldimethylammonium chloride) (PDDA) functionalized graphene (PDDA-G) composite film has been developed for the detection of 4-nitrophenol (4-NP). The PDDA-G was successfully prepared and characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Due to PDDA-G has more functional groups which were beneficial for the absorption of 4-NP by electrostatic interaction, it was found that the sensitivity for 4-nitrophenol was remarkably improved at the PDDA-G nanocomposite film modified GCE. The experimental parameters such as the pH of buffer solution, the scan rate, the accumulation time and potential were optimized. Under the optimum experimental conditions, this sensor had a wide linear range over 4-NP concentration from 0.06μM to 110μM with a detection limit of 0.02μM (S/N=3). Furthermore, the PDDA-G sensor not only exhibited good stability with adequate reproducibility and accuracy, but also demonstrated efficiency in the detection of 4-NP in water samples. It was expected that this method has great promise for simple, sensitive, selective detection of 4-NP.

Supersensitive electrochemical sensor for the fast determination of rutin in pharmaceuticals and biological samples based on poly(diallyldimethylammonium chloride)-functionalized graphene

In this work, poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (PDDA-Gr) was prepared via in situ reduction of exfoliated graphite oxides in the presence of PDDA. The obtained nanostructure was used as a novel immobilization platform for the electrochemical sensor of rutin. PDDA-Gr has superior electrocatalytic activity for the redox of rutin due to its large surface, fast electron transfer character and strong adsorption effect on rutin. The electron transfer rate constant (ks) and the electroactive surface area were calculated as 1.59s−1 and 0.3324cm2 respectively. The saturating absorption capacity (Γ) value of rutin on modified electrode was calculated to be 2.23×10−9molcm−2. Applying differential pulse voltammetry (DPV), a good linear relationship of the reduction peak current and the concentrations of rutin in the range of 0.0004–1.0μM was achieved. The detection limit was 0.04nM (S/N of 3). Under the optimum conditions, the metabolite of rutin, quercetin can be effectively separated from rutin, which suggested the great potential of the proposed method for the practical application in pharmacokinetic and clinical analyses. The method was successfully applied to the fast determination of rutin in medicine tablets and human plasma with satisfactory recoveries.

Preparation of poly(diallyldimethylammonium chloride)-functionalized graphene and its applications for H2O2 and glucose sensing

In this study, poly(diallyldimethylammonium chloride) (PDDA) was selected as an electron acceptor for functionalizing graphene. The resultant PDDA functionalized graphene (PDDA-G) was characterized using TEM, UV–vis absorption spectrum, Raman spectrum and electrochemical method. The PDDA-G modified electrode displayed remarkable electrocatalytic activity toward H2O2 reduction and can be used as a nonenzymatic biosensor for H2O2 detection. Then negatively charged glucose oxidase (GOD) was immobilized onto the positively charged PDDA-G matrix driven by electrostatic interaction. This novel GOD/PDDA-G bionanocomposite can be used as a biosensor for the detection of glucose with a linear range from 0.02 to 1.8mM and a detection limit of 8μM. In this report, the biosensors are easy to prepare, have good stability, and will have potential applications in H2O2 and glucose sensing.

Selective and sensitive determination of uric acid in the presence of ascorbic acid and dopamine by PDDA functionalized graphene/graphite composite electrode

In this work, a facile electrochemical sensor based on poly(diallyldimethylammonium chloride) (PDDA) functionalized graphene (PDDA-G) and graphite was fabricated. The composite electrode exhibited excellent selectivity and sensitivity towards uric acid (UA), owing to the electrocatalytic effect of graphene nanosheets and the electrostatic attractions between PDDA-G and UA. The anodic peak current of UA obtained by cyclic voltammetry (CV) increased over 10-fold compared with bare carbon paste electrode (CPE). And the reversibility of the oxidation process was improved significantly. Differential pulse voltammetry (DPV) was used to determine UA in the presence of ascorbic acid (AA) and dopamine (DA). It was found that all of oxidation peaks of three species could be well resolved, and the peak current of UA was much stronger than the other two components. More importantly, considerable-amount of AA and DA showed negligible interference to UA assay. The calibration curve for UA ranged from 0.5 to 20μmolL−1 with a correlation coefficient of 0.9934. The constructed sensor has been employed to quantitatively determine UA in urine samples.

PtNi Alloy Nanoparticles Supported on Polyelectrolyte Functionalized Graphene as Effective Electrocatalysts for Methanol Oxidation

This paper reports the use of a polyelectrolyte, poly(diallyldimethylammonium chloride) (PDDA), for fabricating bimetallic, highly active PtNi nanocatalysts supported on PDDA-functionalized graphene (P-G). The PDDA-Coating creates a distribution of positive charges on the surfaces of G, which is in favor of the electrostatic self-assembly of negatively charged PtCl62− ions and positively charged Ni2+ ions on the P-G, respectively. The subsequent reduction process by ethylene glycol gives PtNi nanoparticles with uniform distribution on the P-G. The as-made PtNi nanocatalysts supported on the P-G show better activity and stability for the electro-oxidation of methanol compared with pure Pt nanocatalyst supported on the P-G and PtNi nanocatalysts supported on G. Most importantly, the as-made Pt2Ni1/P-G and Pt1Ni1/P-G catalysts display higher activity and stability than the commercial Johnson Matthey PtRu/C (20%) catalyst (JM PtRu/C).

A novel composite film derived from cysteic acid and PDDA-functionalized graphene: Enhanced sensing material for electrochemical determination of metronidazole

A novel composite film derived from cysteic acid and poly(diallydimethylammonium chloride)-functionalized graphene (PDDA-GN) was employed as an enhanced electrode material for ultrasensitive determination of metronidazole. The cysteic acid/PDDA-GN composite film was prepared by the electrochemical grafting of cysteic acid onto the PDDA-GN coated glassy carbon electrode (GCE). The cyclic voltammetry investigations reveal that the peak current of metronidazole reduction at the cysteic acid/PDDA-GN/GCE was remarkably enhanced compared to the bare GCE, the cysteic acid/GCE and the PDDA-GN/GCE. This result implies the synergistic electrocatalytic effect of cysteic acid and PDDA-GN. The fabricated sensor shows linear response to metronidazole in the ranges of 10nM–1μM and 70μM–800μM, with a detection limit of 2.3nM (S/N=3). The heterogeneous electron transfer rate constant and the diffusion coefficient of metronidazole were further evaluated by rotating disk electrode experiments. Moreover, we applied the present method to the determination of metronidazole in urine and lake water with satisfactory results.

An efficient reduction route for the production of Pd–Pt nanoparticles anchored on graphene nanosheets for use as durable oxygen reduction electrocatalysts

Pt and Pd–Pt nanoparticles were anchored on reduced graphene oxide (RGO) with the aid of poly(diallyldimethylammonium chloride) (PDDA), where Pt and Pd ions were first attached to PDDA-functionalized graphene oxide sheets and the encased metal ions and graphene oxide were then reduced simultaneously by ethylene glycol. As supported by transmission electron microscopy, metal nanoparticles, of small particle size even at a high metal loading, were chemically attached to PDDA–RGO. X-ray diffraction indicates that the as-prepared Pd–Pt nanoparticles have a single-phase fcc structure and are principally alloys of Pd and Pt. Among the RGO-supported Pt and Pd–Pt catalysts, Pt nanoparticles anchored on PDDA–RGO exhibit the highest activity for the oxygen reduction reaction (ORR), and the ORR activity of the Pd–Pt alloy electrocatalysts increases with Pt content. All the catalysts demonstrate an enhanced ORR durability when PDDA is present; strongly suggesting that PDDA plays a crucial role in the dispersion and stabilization of the metal nanoparticles on RGO. The ORR activities of the Pd–Pt catalysts remain enhanced even after accelerated durability testing. The formation of a Pt-rich shell, as confirmed by X-ray photoelectron spectroscopy and CO stripping voltammetry, may account for the increased activity.

Simultaneous determination of catechol and hydroquinone based on poly (diallyldimethylammonium chloride) functionalized graphene-modified glassy carbon electrode

Simultaneous determination of catechol (CC) and hydroquinone (HQ) were investigated by voltammetry based on glassy carbon electrode (GCE) modified by poly (diallyldimethylammonium chloride) (PDDA) functionalized graphene (PDDA-G). The modified electrode showed excellent sensitivity and selectivity properties for the two dihydroxybenzene isomers. In 0.1 mol/L phosphate buffer solution (PBS, pH 7.0), the oxidation peak potential difference between CC and HQ was 108 mV, and the peaks on the PDDA-G/GCE were three times as high as the ones on graphene-modified glass carbon electrode. Under optimized conditions, the PDDA-G/GCE showed wide linear behaviors in the range of 1 × 10−6−4 × 10−4 mol/L for CC and 1 × 10−6−5 × 10−4 mol/L for HQ, with the detection limits 2.0 × 10−7 mol/L for CC and 2.5 × 10−7 mol/L for HQ (S/N = 3) in mixture, respectively. Some kinetic parameters, such as the electron transfer number (n), charge transfer coefficient (α), and the apparent heterogeneous electron transfer rate constant (ks), were calculated. The proposed method was applied to simultaneous determine CC and HQ in real water samples of Yellow River with satisfactory results.

Self-assembly of mixed Pt and Au nanoparticles on PDDA-functionalized graphene as effective electrocatalysts for formic acid oxidation of fuel cells

Pt and Au nanoparticles with controlled Pt : Au molar ratios and PtAu nanoparticle loadings were successfully self-assembled onto poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (PDDA-G) as highly effective electrocatalysts for formic acid oxidation in direct formic acid fuel cells (DFAFCs). The simultaneously assembled Pt and Au nanoparticles on PDDA-G showed superb electrocatalytic activity for HCOOH oxidation, and the current density associated with the preferred dehydrogenation pathway for the direct formation of CO(2) through HCOOH oxidation on a Pt(1)Au(8)/PDDA-G (i.e., a Pt : Au ratio of 1 : 8) is 32 times higher than on monometallic Pt/PDDA-G. The main function of the Au in the mixed Pt and Au nanoparticles on PDDA-G is to facilitate the first electron transfer from HCOOH to HCOO(ads) and the effective spillover of HCOO(ads) from Au to Pt nanoparticles, where HCOO(ads) is further oxidized to CO(2). The Pt : Au molar ratio and PtAu nanoparticle loading on PDDA-G supports are the two critical factors to achieve excellent electrocatalytic activity of PtAu/PDDA-G catalysts for the HCOOH oxidation reactions.