1,721,285 research outputs found
Electrochemical and in situ spectroelectrochemical monitoring of the interaction between cobaltphthalocyanines and molecular oxygen in aprotic media
No full textIn this study, voltammetric and spectroelectrochemical measurements of cobaltphthalocyanines (CoPc) bearing different substituents were performed in aprotic solvents to determine the mechanism of interaction between CoPc and molecular oxygen. Metal-based redox processes of the cobaltphthalocyanine complexes indicate their possible electrocatalytic activities toward many target species. Different substituents of the complexes affect the peak characters and assignments of the processes. Presence of O-2 in the electrolyte system influences oxygen reduction reaction and the electrochemical and spectral behaviors of the complexes, which indicate homogeneous electrocatalytic activity of the complexes for the oxygen reduction reaction. In situ electrocolorimetric method was applied to investigate color of the anionic and cationic forms of the complexes. Electrochemical and in situ spectroelectrochemical analysis indicate interaction of molecular oxygen with monoanionic [(CoPc-2)-Pc-1](1-) and presence of an equilibrium between the reactants [(CoPc-2)-Pc-1](1-) and O-2 and the intermediates [O-2(-)-(CoPc2-)-Pc-II](-) and [O-2(2-)-(CoPc2-)-Pc-II](2-). This equilibrium is disturbed in desired direction by changing the excitation signals of the voltammetric and spectroelectrochemical techniques. The intermediates are very unstable, regenerating the starting form of the catalyst and the products O-2(-) and O-2(2-). Interaction rate of O-2 with the complexes is significantly influenced with the steric and coordination properties of the substituents and solvent of the system. Voltammetric and spectroelectrochemical results indicate that homogeneous electrocatalytic ORR follows an inner sphere chemical catalysis process. (C) 2011 Elsevier B.V. All rights reserved
Hydrogen evolution reaction on glassy carbon electrode modified with titanyl phthalocyanines
No full textIn this work, electrocatalytic activities of titanyl phthalocyanines coated on the glassy carbon working electrode(GCE) were investigated for hydrogen evolution reaction by cyclic voltammetry and chronoamperometry. Multi-electron, reversible, diffusion controlled, and metal-based reduction properties of the complexes show possible application as an electrocatalyst for hydrogen evolution reaction in aqueous solution. The complexes are easily electrodeposited on the glassy carbon electrode during the repetitive cycles, a very useful feature for application in fabrication of thin films. It is shown that especially catecholatooctakis(2-dimethylaminoethylsulfanyl phthalocyaninato) titanium(IV) and octakis(2-dimethylaminoethylsulfanyl phthalocyaninato) titanium(IV) derivatives electrodeposited on GCE have significant catalytic activities towards hydrogen evolution reaction. Electrocatalytic activities change irregularly with the pH of the solution. Moreover, the catalytic activity of the complexes enhanced significantly, when the complexes were incorporated into the Nafion polymeric matrix. Octakis(2-dimethylaminoethylsulfanyl phthalocyaninato) titanium(IV) incorporated into Nafion polymeric matrix decreases the overpotential of hydrogen evolution reaction on the glassy carbon electrode upto 0.32 V with augmenting hydrogen discharge current. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved
Copper phthalocyanine complex as electrocatalyst for hydrogen evolution reaction
No full textIn this work, we have sought economically viable methods for hydrogen evolution reaction (her). For this purpose, we have investigated the voltammetric and in situ spectroelectrochemical behavior of copper phthalocyanine complex and its electrocatalytic activity for her. In spite of the belief that the complexes bearing redox active metal center can catalyze hydrogen evolution reactions, copper phthalocyanine having ring-based redox processes shows excellent electrocatalytic activity. (C) 2009 Elsevier B.V. All rights reserved
Phthalocyanine-aniline dyad constructed with click electrochemistry: a novel hybrid electrochromic material
No full textA novel hybrid electrochromic material, dyad of poly 4-azidoaniline (PANI-N-3) and manganese phthalocyanine bearing terminal alkynyl moieties (TA-MnPc), was firstly prepared as an electrochromic anode (ITO/PANI-N-3-TA-MnPc). ITO/PANI-N-3-TA-MnPc was developed to improve the coloration efficiency, switching time, cycle live, and the viability of the phthalocyanine and aniline for the electrochromic applications. Click electrochemistry reaction (CEC) was employed for the binding of TA-MnPc to the electropolymerized PANI-N-3 film on the ITO electrode. Characterization of the constructed electrode was performed with square wave voltammetry (SWV), infra-red spectroscopy (IR), scanning electron microscopy (SEM), and 4-probe conductometer, and then it was tested as a potential electrochromic material. PANI-N-3-TA-MnPc hybrid chromophore provided extraordinary electrochromic responses with improved coloration efficiency, faster switching times, and long cycle live. Color change between green and brown with faster switching times (0.50 s) and longer cycle live (no optical lose with 300 CA cycles) made this hybrid material a possible building blocks for advanced electrochromic devices needing green-brown color change with high optical contrasts and faster response times
Photocatalytic hydrogen production with reduced graphene oxide (RGO)-CdZnS nano-composites synthesized by solvothermal decomposition of dimethyl sulfoxide as the sulfur source
No full textIn order to increase photocatalytic activity, to control particle size and to diminish photo-corrosion of CdZnS based photocatalysts, different compositions of Cd((1-x))Zn(x)Sphotocatalysts were decorated on the reduced graphene oxide (RGO). The target photocatalytic composite structures (RGO-Cd(1-x)ZnxS) were firstly prepared by a solvothermal method using dimethyl sulfoxide (DMSO) as the solvent and sulfur source. RGO-Cd((1-x))Zn(x)Snanocomposites were characterized by the x-ray diffraction (XRD), the transmission electron microscopy (TEM), the scanning electron microscopy (SEM), ultraviolet-visible (UV-vis) diffuse reflectance spectra (DRS), photoluminescence (PL) spectra, The transient photocurrent responses, and the energy-dispersive X-ray spectrometry (EDS). Purity, the particle size of 40 nm, the crystallite sizes between 20.8 and 19.1 angstrom and cubic structure of the photocatalysts could be easily achieved by controlled thermal decomposition of DMSO. Decorating the photocatalysts on RGO structure prevented aggregation of Cd(1-x)ZnxS particles, enhanced transfer of photogenerated charge carriers, and increased the electron transfer rate of the photocatalysts, which provided a better photocatalytic activity. Moreover, loading photo-reduced platinum (Pt) nanoparticles on the RGO-Cd((1-x))Zn(x)Snanocomposite showed a significant increase in hydrogen evolution rate. Among the photocatalysts employed herein, RGO-Cd0.6Zn0.4S-Pt (5%) structure showed the highest activity with 184 mu mol h(-1) hydrogen evolution rate and 24.1% apparent quantum efficiency. Presences of RGO in the nanocomposite structure and synthesizing it with solvothermal method by using DMSO apparently increased the stability and activity of the nanocomposites
Synthesis, in situ spectroelectrochemical, in situ electrocolorimetric and electrocatalytic investigation of brown-manganese phthalocyanines
No full textalpha- and beta-substituted tetrakis(6-hydroxyhexylthiol) phthalocyaninato manganese (III) chloride complexes have been prepared via cyclotetramerization. Both complexes have been characterized by elemental analysis, FTIR, MS and UV-Vis spectral data. The voltammetric and in situ spectroelectrochemical studies reveal that both complexes exhibit an oxidation and three reduction processes having reversible, one-electron, and diffusion controlled mass transfer characteristics, which are assigned to Mn(III)Pc(2-)/Mn(IV)Pc(2-), Mn(III)Pc(2-)/Mn(II)Pc(2-), Mn(II)Pc(2-)/Mn(I)Pc(2-), and Mn(I)Pc(2-)/MnIPc(3-) couples respectively. The existence of oxygen in solution significantly affects the in situ spectroelectrochemical behavior of the complexes due to the formation of mu-oxo MnPc species. An in situ electrocolorimetric method has been applied to investigate the colors of the electro-generated anionic and cationic forms of the complexes for the first time in this study. The complexes, coated on a glassy carbon electrode potentio-statically, show considerable high electrocatalytic activity to hydrogen evolution reactions in aqueous solution. (C) 2009 Elsevier Ltd. All rights reserved
An electrochemical sensor for the detection of pesticides based on the hybrid of manganese phthalocyanine and polyaniline
No full textA mimic enzymeless electrochemical sensor (M-Eless-ES) based on the terminal alkynyl substituted manganese phthalocyanine (MnPc-TA) and 4-azido polyaniline (N-3-PANI) hybrid was constructed and tested as a selective and sensitive pesticide sensor. A new electrode modification technique, solid state electropolymerization of a film, was developed for the preparation of ITO/MnPc-TA/N-3-PANI electrode as M-Eless-ES for the first time in this study. During construction of ITO/MnPc-TA/N(3-)PANI electrode, MnPc-TA was firstly deposited on indium tin oxide coated glass substrate (ITO) with Langmuir Blodgett (LB) technique. Then 4-azidoaniline (N-3-ANI) was bonded to the terminal alkynyl substituents of MnPc-TA (ITO/MnPc-TA/N-3-ANI) with click chemistry (CC) and finally ANI groups of the solid MnPc-TA/N-3-ANI hybrid film was electropolymerized on ITO surface to form ITO/MnPc-TA/N-3-PANI electrode. The modified electrode was characterized with square wave voltammetry (SWV), X-ray diffraction (XRD), scanning electron microscope (SEM), and fourier transform infrared (FT-IR). Finally, ITO/MnPc-TA/N-3-PANI electrode was tested as potential M-Eless-ES for the fenitrothion, eserine, and diazinon via SWV technique. Different voltammetric responses were observed for each pesticide. Observation of a new redox peak due to the interaction of the electrode with the fenitrothion indicated its distinct selectivity for this pesticide. The limit of detection (LOD) (0.049 mu mol dm(-3) for fenitrothion, 0.088 mu mol dm(-3) for eserine and 0.062 mu mol dm(-3) for diazinon), wide linear ranges, and especially higher selectivity were observed with ITO/MnPc-TA/N-3-PANI which are the basic requirements for the practical applications for the pesticide sensing. Reproducibility, easy of construction, and stability of the electrode are other superior advantages. As a real sample application, ITO/MnPc-TA/N-3-PANI sensor was successfully employed for determining the fenitrothion residue in rosehip sample
Photo-Induced Phase Transition of CdZnS Based Nanocomposite at Room Temperature Under Solar Irradiation
No full textPhoto-induced phase transition (PIPT) of CdZnS based nanocomposites that was performed at the room temperature under the solar light illumination is reported here for the first time. CdZnS particles were decorated on reduced graphene oxide (RGO) with a solvothermal process and consequently RGO-CdZnS-5%Pt nanocomposites (PC) have been synthesized as zinc blende (cubic) phase of CdZnS. Zinc blende structure (cubic) of CdZnS components of PC was turned to wurtzite (hexagonal) crystal structure with PIPT during the photocatalytic hydrogen evolution reaction. The band gap of the photocatalyst decreased from 2.42 to 2.19eV and the hydrogen evolution rate increased from 37.3 to 184.0 mu mol h(-1) due to the PIPT process. [GRAPHICS]
Construction of Modified Electrodes with Click Electrochemistry Based on the Hybrid of 4-Azido Aniline and Manganese Phthalocyanine and Electrochemical Pesticide Sensor Applications
No full textTerminal alkynyl substituted manganese phthalocyanine (TA-MnPc) was bounded to 4-azido polyaniline (PANI-N-3) on an indium thin oxide coated glass (ITO) electrode by using click electrochemistry (CEC) method in order to prepare PANI-N-3/TA-MnPc hybrid. Constructed ITO/PANI-N-3/TA-MnPc electrode was characterized with square wave voltammetry (SWV), scanning electron microscope (SEM), and Fourier transform infrared (FT-IR) spectra and then it was investigated as a mimic enzymeless electrochemical sensor (M-Eless-ES) for the pesticide detection. During construction of ITO/PANI-N-3/TA-MnPc electrode, 4-azidoaniline (ANI-N-3) was firstly coated on the ITO surface with the electropolymerization of ANI-N-3 and hereby ITO/PANI-N-3 electrode bearing functional azide groups was prepared. Then TA-MnPc was bounded to the azide groups of ITO/PANI-N-3 electrode with CEC by forming threeazole ring between the azide and terminal alkynyl groups with the catalytic assist of Cu-I ions generated electrochemically on the surface of the electrode. Finally, ITO/PANI-N-3/TA-MnPc electrode was tested as a potential M-Eless-ES for various pesticides. While PANI-N-3/TA-MnPc hybrid interacted with all pesticides, the interaction with the fenitrothion showed completely different voltammetric results than the others. Observation of a new characteristic peak for the fenitrothion sensing illustrated selectivity of the electrode for this pesticide. In addition to the better selectivity, good stability, reproducibility, small detection limit (LOD), high sensitivity, and wide linear range of the electrode indicated possible application of ITO/PANI-N-3/TA-MnPc electrode as a practical pesticide sensor. (C) 2018 The Electrochemical Society
Novel 4-(2-(benzo[d]thiazol-2-yl)phenoxy) substituted phthalocyanine derivatives: Synthesis, electrochemical and in situ spectroelectrochemical characterization
No full textIn this study, the new tetra peripherally 4-(2-(benzo[d]thiazol-2-yl)phenoxy)-substituted metal-free (4), zinc(II) (5), lead(II) (6), cobalt(II) (7) and copper(II) (8) phthalocyanine derivatives, which are organosoluble, have been synthesized for the first time and their structures characterized by using electronic absorption, infrared spectroscopy, nuclear magnetic resonance spectroscopy, elemental analysis and mass spectra. Voltammetric characterization of the phthalocyanine derivatives (4-7) was performed with cyclic voltammetry and square wave voltammetry. Cobalt phthalocyanine (7) gave metal based electron transfer reactions in addition to the phthalocyanine ring based reduction and oxidation reactions. Although lead phthalocyanine (6) illustrated reversible reduction process during the voltammetric measurements, it was de-metallized and thus it turned back to the metal free phthalocyanine during the in situ spectroelectrochemical measurements under the applied potentials. Spectroelectrochemical measurements were performed to assign the redox processes and spectroscopic responses of the electrogenerated species. (C) 2014 Elsevier B.V. All rights reserved
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