Kenneth Ikechukwu I Ozoemena - Academia.edu (original) (raw)

Papers by Kenneth Ikechukwu I Ozoemena

Research paper thumbnail of Microwave-Assisted Synthesis of Palladium-Decorated FeCo@Fe/C Core-Shell: Applications in Direct Alcohol Alkaline Fuel Cells

Research paper thumbnail of Nitrogen-Enriched Metallophthalocyanine/Graphene Oxide Nanocomposites for High-Energy Asymmetric Electrochemical Capacitors in Aqueous Electrolytes

Research paper thumbnail of Tuning the Electrolytic Manganese Oxide/Graphene Oxide Nanocomposites for High-Energy Asymmetric Electrochemical Capacitors in Aqueous Electrolytes

Research paper thumbnail of Layer-by-layer self-assembled nanostructured phthalocyaninatoiron(II)/SWCNT poly(m-aminobenzenesulfonic acid) hybrid system on gold surface: Electron transfer dynamics and amplification of H2O2 response

Electrochimica Acta, 2009

The fabrication of nanostructured platform of poly(m-aminobenzenesulfonic acid) functionalised si... more The fabrication of nanostructured platform of poly(m-aminobenzenesulfonic acid) functionalised single-walled carbon nanotubes (SWCNTs-PABS)-iron(II)phthalocyanine nanoparticles (nanoFePc) using layer-by-layer(LBL) self-assembly strategy is described. The substrate build-up, via strong electrostatic interaction, was monitored using atomic force microscopy (AFM) and electrochemical measurements. As the number of bilayers is increased, the electron transfer kinetics of the ferricyaninde/ferrocyanide redox probe is decreased, while the electrochemical reduction of H 2 O 2 at a constant concentration is amplified. The amplification of the electrochemical response to H 2 O 2 detection suggests that this type of electrode could provide an important nano-architectural sensing platform for the development of a sensor.

Research paper thumbnail of Synthesis and electrochemical characterisation of benzylmercapto and dodecylmercapto tetra substituted cobalt, iron, and zinc phthalocyanines complexes

Electrochimica Acta, Jun 1, 2006

The work reports on cyclic voltammetry (CV), square wave voltammetry and spectroelectrochemistry ... more The work reports on cyclic voltammetry (CV), square wave voltammetry and spectroelectrochemistry of the following complexes: tetrakis (benzylmercapto) phthalocyanine complexes of Zn(II) (ZnTBMPc, 4a), Co(II) (CoTBMPc, 5a), and Fe(II) (FeTBMPc 6a); tetrakis (dodecylmercapto) phthalocyanine complexes of Zn(II) (ZnTDMPc, 4b), Co(II) (CoTDMPc, 5b), and Fe(II) (FeTDMPc, 6b). More reversible CV couples were observed for complexes 4a, 5a, and 6a containing thiol phenyl ring substituents. Complexes 4b, 5b, and 6b containing long chain thiol substituents showed less reversible couples. Complexes 6a and 6b showed a relatively large number of redox processes (5 for 6a and 6 for 6b) within the potential window employed in this work. The processes for FePc derivatives (6a) are assigned to FeIIIPc−1/FeIIIPc−2, FeIIIPc−2/FeIIPc−2, FeIIPc−2/FeIPc−2, FeIPc−2/FeIPc−3, and FeIPc−3/FeIPc−4 and for the CoPc derivative (5a) to CoIIIPc−1/CoIIIPc−2, CoIIIPc−2/CoIIPc−2, CoIIPc−2/CoIPc−2, and CoIPc−2/CoIPc−3.

Research paper thumbnail of Comparative photosensitised transformation of polychlorophenols with different sulphonated metallophthalocyanine complexes in aqueous medium

Journal of Molecular Catalysis a Chemical, Nov 20, 2001

... Sulphonation often gives the mixture of differently substituted Pc metallocomplexes (MPcS mix... more ... Sulphonation often gives the mixture of differently substituted Pc metallocomplexes (MPcS mix , where M is the metal ion, n=1, 2, 3, and 4). The degree of sulphonation, isomeric composition and the nature of the central metal ion affect the extent of aggregation. ...

Research paper thumbnail of Cyclic voltammetric studies of octabutylthiophthalo-cyaninato-cobalt(II) and its self-assembled monolayer (SAM) on gold electrode

J Porphyr Phthalocya, 2002

The synthesis of thiol-derivatized cobalt phthalocyanine complex, 2,3,9,10,16,17,23,24-octa (buty... more The synthesis of thiol-derivatized cobalt phthalocyanine complex, 2,3,9,10,16,17,23,24-octa (butylthiophthalocyaninatocobalt(II) ( CoOBTPc ) is described. Cyclic voltammetric data of this complex in DMF showed five quasi-reversible and reversible, diffusion-controlled redox couples, comprising both the phthalocyanine ring and central metal redox processes. The CoOBTPc complex forms a self-assembled monolayer (SAM) on gold electrode. The investigation of the integrity of this SAM, using the established cyclic voltammetric methods in aqueous alkaline solutions, gave evidence about the formation of a stable and easily reproducible monolayer. However, due to its susceptibility to destruction via oxidative and reductive desorptions, its potential application as an electrochemical sensor in alkaline pH is limited to a potential window of between −0.20 and +0.55 V vs Ag / AgCl .

Research paper thumbnail of Enantioselective, potentiometric membrane electrodes based on maltodextrins

Sensor Actuator B Chem, 2004

ABSTRACT

Research paper thumbnail of Metal (Co, Fe) tribenzotetraazachlorin-fullerene conjugates: impact of direct p-bonding on the redox behaviour and oxygen reduction reaction

Novel hexabutylsulphonyltribenzotetraazachlorin-fullerene (C 60) complexes of iron (FeHBSTBTAC-C ... more Novel hexabutylsulphonyltribenzotetraazachlorin-fullerene (C 60) complexes of iron (FeHBSTBTAC-C 60) 25 and cobalt (CoHBSTBTAC-C 60) have been synthesized and their electrochemistry and oxygen reduction 26 reaction (ORR) compared with their octabutylsulphonylphthalocyanine analogues (FeOBSPc and CoO-27 BSPc). It is proved that electron-withdrawing substituents (-SO 2 Bu and C 60) on phthalocyanine macrocy-28 cle exhibit distinct impact on the solution electrochemistry of these metallophthalocyanine (MPc) 29 complexes. The more electron-withdrawing C 60 substituent suppressed ORR compared to the-SO 2 Bu 30 in alkaline medium. FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, a 31 rate constant of $1 Â 10 8 cm 3 mol À1 s À1 and a Tafel slope of À171 mV dec À1. 32

Research paper thumbnail of Synthesis and electrochemical properties of benzyl-mercapto and dodecyl-mercapto tetrasubstituted manganese phthalocyanine complexes

Electrochimica Acta, Feb 1, 2007

Manganese tetrakis (benzyl-mercapto) phthalocyanine (MnTBMPc) and manganese tetrakis (dodecyl-mer... more Manganese tetrakis (benzyl-mercapto) phthalocyanine (MnTBMPc) and manganese tetrakis (dodecyl-mercapto) phthalocyanine (MnTDMPc) complexes were synthesized and their spectral and electrochemical properties are reported. Cyclic voltammetric data showed three reversible to quasi-reversible and two irreversible redox processes for both complexes. Ring substituents influenced the positions of both oxidation and reduction redox couples. Spectroelectrochemistry confirmed the first two reductions to be due to Mn III Pc 2− /Mn II Pc 2− and Mn II Pc 3− /Mn II Pc 2− processes. The first example of a formation of self-assembled monolayers (SAMs) using thiol substituted MnPc complexes is presented, the SAMs were found to show blocking characteristics towards some faradaic reactions. Article Outline 1. Introduction 2. Experimental 2.1. Materials and reagents 2.2. Apparatus and procedure 2.3. Synthesis 2.3.1. Manganese(III)acetate tetrakis (benzyl-mercapto) phthalocyanine, Mn(OAc)TBMPc, complex 3a 2.3.2. Manganese(III)acetate tetrakis (dodecyl-mercapto) phthalocyanine, Mn(OAc)TDMPc, complex 3b 2.4. Procedure for self-assembled monolayers formation 3. Results and discussion 3.1. Synthesis and spectral characterisation 3.2. Voltammetric and spectroelectrochemical studies openUP-February 2007 3.3. Formation of self-assembled monolayers (SAMs) 4. Conclusion

Research paper thumbnail of Long-term stability of a gold electrode modified with a self-assembled monolayer of octabutylthiophthalocyaninato-cobalt(II) towards l-cysteine detection

Electrochemistry Communications, Sep 30, 2001

In this paper, a gold electrode, modified with octabutylthiophthalocyaninato-cobalt(II) self-asse... more In this paper, a gold electrode, modified with octabutylthiophthalocyaninato-cobalt(II) self-assembled monolayer (SAM), was used in the detection of l-cysteine in pH=4 buffer. The SAM showed good electrocatalytic activity and increased the electron transfer rate in such a way that mass-transport became the rate determining step of the overall oxidation reaction of l-cysteine. From these data the diffusion coefficient of l-cysteine

Research paper thumbnail of Electron transport and electrocatalytic properties of MWCNT/nickel nanocomposites: Hydrazine and diethylaminoethanethiol as analytical probes

Journal of Electroanalytical Chemistry, Jun 1, 2010

This work describes the electron transport and electrocatalytic properties of chemically-synthesi... more This work describes the electron transport and electrocatalytic properties of chemically-synthesized nickel (Ni) and nickel oxide (NiO) nanoparticles supported on multi-walled carbon nanotubes (MWCNT) platforms. Successful modification of the electrodes with the Ni and NiO nanoparticles was confirmed by techniques such as FTIR, FESEM, HRSEM, TEM, XRD, EDX and cyclic voltammetry (CV). The electrocatalytic oxidation of DEAET and hydrazine on the modified electrodes was investigated using CV and electrochemical impedance spectroscopy (EIS) and discussed. Results showed that EPPGE-MWCNT-Ni electrode gave the best electro-oxidation response towards DEAET and hydrazine. The catalytic rate constant and the limit of detection of the electrode to DEAET and hydrazine were 5.93 Â 10 9 cm 3 mol À1 s À1 (0.87 lM) and 7.67 Â 10 8 cm 3 mol À1 s À1 (0.29 lM), respectively. The electrochemical Gibbs free energy change due to adsorption (DG 0) for the EPPGE-MWCNT-Ni in DEAET and hydrazine were estimated as À18.14 and À17.21 kJ mol À1 , respectively. The electrode has proven to be a potential electrochemical sensor for DEAET and hydrazine.

Research paper thumbnail of Long-term stability of a gold electrode modified with a self-assembled monolayer of octabutylthiophthalocyaninato-cobalt(II) towards ?-cysteine detection

Electrochem Commun, 2001

In this paper, a gold electrode, modified with octabutylthiophthalocyaninato-cobalt(II) self-asse... more In this paper, a gold electrode, modified with octabutylthiophthalocyaninato-cobalt(II) self-assembled monolayer (SAM), was used in the detection of l-cysteine in pH=4 buffer. The SAM showed good electrocatalytic activity and increased the electron transfer rate in such a way that mass-transport became the rate determining step of the overall oxidation reaction of l-cysteine. From these data the diffusion coefficient of l-cysteine

Research paper thumbnail of Enantioselective, Potentiometric Membrane Electrode, Based on Vancomycin as Chiral Selector, for the Assay of S-Perindopril

Instrum Sci Technol, 2004

ABSTRACT

Research paper thumbnail of Efficient electron transport across nickel powder modified basal plane pyrolytic graphite electrode: Sensitive detection of sulfhydryl degradation products of the V-type nerve agents

Electrochemistry Communications, Jul 1, 2007

ABSTRACT This communication describes the electron transport behaviour of basal plane pyrolytic g... more ABSTRACT This communication describes the electron transport behaviour of basal plane pyrolytic graphite electrodes (BPPGEs) modified with nickel powder (BPPGE-Ni), single-walled carbon nanotube (BPPGE-SWCNT) and BPPGE-Ni decorated with SWCNT via drop-dry method (BPPGE-Ni-SWCNT). The BPPGE-Ni gave enhanced Faradaic response for the redox probe (Ferricyanide/Ferrocyanide species) and also displayed enhanced electrocatalytic behaviour towards the detection of degradation products of V-type nerve agents, dimethylaminoethanethiol (DMAET) and diethylaminoethanethiol (DEAET) with high sensitivity (∼23 × 10−3 AM−1) and low detection limits (4.0–9.0 μM range). When compared to the notable electrodes and detection protocols reported in the literature, BPPGE-Ni exhibits more promising features required for a simple, highly sensitive, fast and less expensive electrode for the detection of these V-type nerve agents in aqueous solution. The efficient response of the BPPGE-Ni is attributed to the high microscopic surface area of the nickel powder. The poor response of the BPPGE-Ni-SWCNT suggests that nickel impurity in the SWCNT did not show any detectable impact on its electron transfer kinetics.

Research paper thumbnail of Novel iron-cobalt derivatised lithium iron phosphate nanocomposite for lithium ion battery cathode

International Journal of Electrochemical Science, 2013

Described herein is the electrochemical study conducted on lithium ion battery cathode material c... more Described herein is the electrochemical study conducted on lithium ion battery cathode material consisting of composite of lithium iron phosphate (LiFePO 4), iron-cobalt derivatised carbon nanotubes (FeCo-CNT) and polyaniline (PA) nanomaterials (LiFePO4/FeCoCNT-PA); and pristine LiFePO 4. The design of the nanocomposite electrode involves first, the attachment of FeCo nanoparticles unto the nanotubes matrix via in situ reductive precipitation of the metal precursors within a CNT suspension. Results from High Resolution Transmission Electron Microscopy show the successful attachment of FeCo nanoparticles to the CNTs. The composite cathode exhibits better reversibility and kinetics than the pristine LiFePO 4 due to the presence of the conductive additives in the former. This is demonstrated in the values of the diffusion coefficient (D) and standard rate constant (k s) determined through cyclic voltammetry. For the composite cathode D = 1.0 x 10-9 cm 2 s-1 and k s = 7.05 x 10-7 cm s-1 whereas the pristine electrode has values of 4.81 x 10-11 cm 2 s-1 and 2.68 x 10-7 cm s-1 for D and k s , respectively. Similar trend is observed in the results obtained from electrochemical impedance spectroscopy.

Research paper thumbnail of Recent advances in analytical electrochemistry

Research paper thumbnail of Determination of 2′,3′‐Dideoxyinosine Using Iron (II) Phthalocyanine Modified Carbon Paste Electrode

Analytical Letters, 2004

Abstract An amperometric sensor, based on carbon paste impregnated with iron (II) phthalocyanine ... more Abstract An amperometric sensor, based on carbon paste impregnated with iron (II) phthalocyanine complex (FePc), has been constructed for the assay of anti‐HIV agent dideoxyinosine (didanosine, DDI). Using chronoamperometry (E=+ 1.04 V versus Ag/AgCl ...

Research paper thumbnail of Utilization of Maltodextrin‐Based Enantioselective, Potentiometric Membrane Electrodes for the Enantioselective Assay of S‐Flurbiprofen

Http Dx Doi Org 10 1080 00032710600620401, Oct 25, 2011

ABSTRACT

Research paper thumbnail of Graphitic carbon anchored sulphonated and transition metal oxide doped polyaniline nanocomposite materials for supercapacitor electrodes

Research paper thumbnail of Microwave-Assisted Synthesis of Palladium-Decorated FeCo@Fe/C Core-Shell: Applications in Direct Alcohol Alkaline Fuel Cells

Research paper thumbnail of Nitrogen-Enriched Metallophthalocyanine/Graphene Oxide Nanocomposites for High-Energy Asymmetric Electrochemical Capacitors in Aqueous Electrolytes

Research paper thumbnail of Tuning the Electrolytic Manganese Oxide/Graphene Oxide Nanocomposites for High-Energy Asymmetric Electrochemical Capacitors in Aqueous Electrolytes

Research paper thumbnail of Layer-by-layer self-assembled nanostructured phthalocyaninatoiron(II)/SWCNT poly(m-aminobenzenesulfonic acid) hybrid system on gold surface: Electron transfer dynamics and amplification of H2O2 response

Electrochimica Acta, 2009

The fabrication of nanostructured platform of poly(m-aminobenzenesulfonic acid) functionalised si... more The fabrication of nanostructured platform of poly(m-aminobenzenesulfonic acid) functionalised single-walled carbon nanotubes (SWCNTs-PABS)-iron(II)phthalocyanine nanoparticles (nanoFePc) using layer-by-layer(LBL) self-assembly strategy is described. The substrate build-up, via strong electrostatic interaction, was monitored using atomic force microscopy (AFM) and electrochemical measurements. As the number of bilayers is increased, the electron transfer kinetics of the ferricyaninde/ferrocyanide redox probe is decreased, while the electrochemical reduction of H 2 O 2 at a constant concentration is amplified. The amplification of the electrochemical response to H 2 O 2 detection suggests that this type of electrode could provide an important nano-architectural sensing platform for the development of a sensor.

Research paper thumbnail of Synthesis and electrochemical characterisation of benzylmercapto and dodecylmercapto tetra substituted cobalt, iron, and zinc phthalocyanines complexes

Electrochimica Acta, Jun 1, 2006

The work reports on cyclic voltammetry (CV), square wave voltammetry and spectroelectrochemistry ... more The work reports on cyclic voltammetry (CV), square wave voltammetry and spectroelectrochemistry of the following complexes: tetrakis (benzylmercapto) phthalocyanine complexes of Zn(II) (ZnTBMPc, 4a), Co(II) (CoTBMPc, 5a), and Fe(II) (FeTBMPc 6a); tetrakis (dodecylmercapto) phthalocyanine complexes of Zn(II) (ZnTDMPc, 4b), Co(II) (CoTDMPc, 5b), and Fe(II) (FeTDMPc, 6b). More reversible CV couples were observed for complexes 4a, 5a, and 6a containing thiol phenyl ring substituents. Complexes 4b, 5b, and 6b containing long chain thiol substituents showed less reversible couples. Complexes 6a and 6b showed a relatively large number of redox processes (5 for 6a and 6 for 6b) within the potential window employed in this work. The processes for FePc derivatives (6a) are assigned to FeIIIPc−1/FeIIIPc−2, FeIIIPc−2/FeIIPc−2, FeIIPc−2/FeIPc−2, FeIPc−2/FeIPc−3, and FeIPc−3/FeIPc−4 and for the CoPc derivative (5a) to CoIIIPc−1/CoIIIPc−2, CoIIIPc−2/CoIIPc−2, CoIIPc−2/CoIPc−2, and CoIPc−2/CoIPc−3.

Research paper thumbnail of Comparative photosensitised transformation of polychlorophenols with different sulphonated metallophthalocyanine complexes in aqueous medium

Journal of Molecular Catalysis a Chemical, Nov 20, 2001

... Sulphonation often gives the mixture of differently substituted Pc metallocomplexes (MPcS mix... more ... Sulphonation often gives the mixture of differently substituted Pc metallocomplexes (MPcS mix , where M is the metal ion, n=1, 2, 3, and 4). The degree of sulphonation, isomeric composition and the nature of the central metal ion affect the extent of aggregation. ...

Research paper thumbnail of Cyclic voltammetric studies of octabutylthiophthalo-cyaninato-cobalt(II) and its self-assembled monolayer (SAM) on gold electrode

J Porphyr Phthalocya, 2002

The synthesis of thiol-derivatized cobalt phthalocyanine complex, 2,3,9,10,16,17,23,24-octa (buty... more The synthesis of thiol-derivatized cobalt phthalocyanine complex, 2,3,9,10,16,17,23,24-octa (butylthiophthalocyaninatocobalt(II) ( CoOBTPc ) is described. Cyclic voltammetric data of this complex in DMF showed five quasi-reversible and reversible, diffusion-controlled redox couples, comprising both the phthalocyanine ring and central metal redox processes. The CoOBTPc complex forms a self-assembled monolayer (SAM) on gold electrode. The investigation of the integrity of this SAM, using the established cyclic voltammetric methods in aqueous alkaline solutions, gave evidence about the formation of a stable and easily reproducible monolayer. However, due to its susceptibility to destruction via oxidative and reductive desorptions, its potential application as an electrochemical sensor in alkaline pH is limited to a potential window of between −0.20 and +0.55 V vs Ag / AgCl .

Research paper thumbnail of Enantioselective, potentiometric membrane electrodes based on maltodextrins

Sensor Actuator B Chem, 2004

ABSTRACT

Research paper thumbnail of Metal (Co, Fe) tribenzotetraazachlorin-fullerene conjugates: impact of direct p-bonding on the redox behaviour and oxygen reduction reaction

Novel hexabutylsulphonyltribenzotetraazachlorin-fullerene (C 60) complexes of iron (FeHBSTBTAC-C ... more Novel hexabutylsulphonyltribenzotetraazachlorin-fullerene (C 60) complexes of iron (FeHBSTBTAC-C 60) 25 and cobalt (CoHBSTBTAC-C 60) have been synthesized and their electrochemistry and oxygen reduction 26 reaction (ORR) compared with their octabutylsulphonylphthalocyanine analogues (FeOBSPc and CoO-27 BSPc). It is proved that electron-withdrawing substituents (-SO 2 Bu and C 60) on phthalocyanine macrocy-28 cle exhibit distinct impact on the solution electrochemistry of these metallophthalocyanine (MPc) 29 complexes. The more electron-withdrawing C 60 substituent suppressed ORR compared to the-SO 2 Bu 30 in alkaline medium. FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, a 31 rate constant of $1 Â 10 8 cm 3 mol À1 s À1 and a Tafel slope of À171 mV dec À1. 32

Research paper thumbnail of Synthesis and electrochemical properties of benzyl-mercapto and dodecyl-mercapto tetrasubstituted manganese phthalocyanine complexes

Electrochimica Acta, Feb 1, 2007

Manganese tetrakis (benzyl-mercapto) phthalocyanine (MnTBMPc) and manganese tetrakis (dodecyl-mer... more Manganese tetrakis (benzyl-mercapto) phthalocyanine (MnTBMPc) and manganese tetrakis (dodecyl-mercapto) phthalocyanine (MnTDMPc) complexes were synthesized and their spectral and electrochemical properties are reported. Cyclic voltammetric data showed three reversible to quasi-reversible and two irreversible redox processes for both complexes. Ring substituents influenced the positions of both oxidation and reduction redox couples. Spectroelectrochemistry confirmed the first two reductions to be due to Mn III Pc 2− /Mn II Pc 2− and Mn II Pc 3− /Mn II Pc 2− processes. The first example of a formation of self-assembled monolayers (SAMs) using thiol substituted MnPc complexes is presented, the SAMs were found to show blocking characteristics towards some faradaic reactions. Article Outline 1. Introduction 2. Experimental 2.1. Materials and reagents 2.2. Apparatus and procedure 2.3. Synthesis 2.3.1. Manganese(III)acetate tetrakis (benzyl-mercapto) phthalocyanine, Mn(OAc)TBMPc, complex 3a 2.3.2. Manganese(III)acetate tetrakis (dodecyl-mercapto) phthalocyanine, Mn(OAc)TDMPc, complex 3b 2.4. Procedure for self-assembled monolayers formation 3. Results and discussion 3.1. Synthesis and spectral characterisation 3.2. Voltammetric and spectroelectrochemical studies openUP-February 2007 3.3. Formation of self-assembled monolayers (SAMs) 4. Conclusion

Research paper thumbnail of Long-term stability of a gold electrode modified with a self-assembled monolayer of octabutylthiophthalocyaninato-cobalt(II) towards l-cysteine detection

Electrochemistry Communications, Sep 30, 2001

In this paper, a gold electrode, modified with octabutylthiophthalocyaninato-cobalt(II) self-asse... more In this paper, a gold electrode, modified with octabutylthiophthalocyaninato-cobalt(II) self-assembled monolayer (SAM), was used in the detection of l-cysteine in pH=4 buffer. The SAM showed good electrocatalytic activity and increased the electron transfer rate in such a way that mass-transport became the rate determining step of the overall oxidation reaction of l-cysteine. From these data the diffusion coefficient of l-cysteine

Research paper thumbnail of Electron transport and electrocatalytic properties of MWCNT/nickel nanocomposites: Hydrazine and diethylaminoethanethiol as analytical probes

Journal of Electroanalytical Chemistry, Jun 1, 2010

This work describes the electron transport and electrocatalytic properties of chemically-synthesi... more This work describes the electron transport and electrocatalytic properties of chemically-synthesized nickel (Ni) and nickel oxide (NiO) nanoparticles supported on multi-walled carbon nanotubes (MWCNT) platforms. Successful modification of the electrodes with the Ni and NiO nanoparticles was confirmed by techniques such as FTIR, FESEM, HRSEM, TEM, XRD, EDX and cyclic voltammetry (CV). The electrocatalytic oxidation of DEAET and hydrazine on the modified electrodes was investigated using CV and electrochemical impedance spectroscopy (EIS) and discussed. Results showed that EPPGE-MWCNT-Ni electrode gave the best electro-oxidation response towards DEAET and hydrazine. The catalytic rate constant and the limit of detection of the electrode to DEAET and hydrazine were 5.93 Â 10 9 cm 3 mol À1 s À1 (0.87 lM) and 7.67 Â 10 8 cm 3 mol À1 s À1 (0.29 lM), respectively. The electrochemical Gibbs free energy change due to adsorption (DG 0) for the EPPGE-MWCNT-Ni in DEAET and hydrazine were estimated as À18.14 and À17.21 kJ mol À1 , respectively. The electrode has proven to be a potential electrochemical sensor for DEAET and hydrazine.

Research paper thumbnail of Long-term stability of a gold electrode modified with a self-assembled monolayer of octabutylthiophthalocyaninato-cobalt(II) towards ?-cysteine detection

Electrochem Commun, 2001

In this paper, a gold electrode, modified with octabutylthiophthalocyaninato-cobalt(II) self-asse... more In this paper, a gold electrode, modified with octabutylthiophthalocyaninato-cobalt(II) self-assembled monolayer (SAM), was used in the detection of l-cysteine in pH=4 buffer. The SAM showed good electrocatalytic activity and increased the electron transfer rate in such a way that mass-transport became the rate determining step of the overall oxidation reaction of l-cysteine. From these data the diffusion coefficient of l-cysteine

Research paper thumbnail of Enantioselective, Potentiometric Membrane Electrode, Based on Vancomycin as Chiral Selector, for the Assay of S-Perindopril

Instrum Sci Technol, 2004

ABSTRACT

Research paper thumbnail of Efficient electron transport across nickel powder modified basal plane pyrolytic graphite electrode: Sensitive detection of sulfhydryl degradation products of the V-type nerve agents

Electrochemistry Communications, Jul 1, 2007

ABSTRACT This communication describes the electron transport behaviour of basal plane pyrolytic g... more ABSTRACT This communication describes the electron transport behaviour of basal plane pyrolytic graphite electrodes (BPPGEs) modified with nickel powder (BPPGE-Ni), single-walled carbon nanotube (BPPGE-SWCNT) and BPPGE-Ni decorated with SWCNT via drop-dry method (BPPGE-Ni-SWCNT). The BPPGE-Ni gave enhanced Faradaic response for the redox probe (Ferricyanide/Ferrocyanide species) and also displayed enhanced electrocatalytic behaviour towards the detection of degradation products of V-type nerve agents, dimethylaminoethanethiol (DMAET) and diethylaminoethanethiol (DEAET) with high sensitivity (∼23 × 10−3 AM−1) and low detection limits (4.0–9.0 μM range). When compared to the notable electrodes and detection protocols reported in the literature, BPPGE-Ni exhibits more promising features required for a simple, highly sensitive, fast and less expensive electrode for the detection of these V-type nerve agents in aqueous solution. The efficient response of the BPPGE-Ni is attributed to the high microscopic surface area of the nickel powder. The poor response of the BPPGE-Ni-SWCNT suggests that nickel impurity in the SWCNT did not show any detectable impact on its electron transfer kinetics.

Research paper thumbnail of Novel iron-cobalt derivatised lithium iron phosphate nanocomposite for lithium ion battery cathode

International Journal of Electrochemical Science, 2013

Described herein is the electrochemical study conducted on lithium ion battery cathode material c... more Described herein is the electrochemical study conducted on lithium ion battery cathode material consisting of composite of lithium iron phosphate (LiFePO 4), iron-cobalt derivatised carbon nanotubes (FeCo-CNT) and polyaniline (PA) nanomaterials (LiFePO4/FeCoCNT-PA); and pristine LiFePO 4. The design of the nanocomposite electrode involves first, the attachment of FeCo nanoparticles unto the nanotubes matrix via in situ reductive precipitation of the metal precursors within a CNT suspension. Results from High Resolution Transmission Electron Microscopy show the successful attachment of FeCo nanoparticles to the CNTs. The composite cathode exhibits better reversibility and kinetics than the pristine LiFePO 4 due to the presence of the conductive additives in the former. This is demonstrated in the values of the diffusion coefficient (D) and standard rate constant (k s) determined through cyclic voltammetry. For the composite cathode D = 1.0 x 10-9 cm 2 s-1 and k s = 7.05 x 10-7 cm s-1 whereas the pristine electrode has values of 4.81 x 10-11 cm 2 s-1 and 2.68 x 10-7 cm s-1 for D and k s , respectively. Similar trend is observed in the results obtained from electrochemical impedance spectroscopy.

Research paper thumbnail of Recent advances in analytical electrochemistry

Research paper thumbnail of Determination of 2′,3′‐Dideoxyinosine Using Iron (II) Phthalocyanine Modified Carbon Paste Electrode

Analytical Letters, 2004

Abstract An amperometric sensor, based on carbon paste impregnated with iron (II) phthalocyanine ... more Abstract An amperometric sensor, based on carbon paste impregnated with iron (II) phthalocyanine complex (FePc), has been constructed for the assay of anti‐HIV agent dideoxyinosine (didanosine, DDI). Using chronoamperometry (E=+ 1.04 V versus Ag/AgCl ...

Research paper thumbnail of Utilization of Maltodextrin‐Based Enantioselective, Potentiometric Membrane Electrodes for the Enantioselective Assay of S‐Flurbiprofen

Http Dx Doi Org 10 1080 00032710600620401, Oct 25, 2011

ABSTRACT

Research paper thumbnail of Graphitic carbon anchored sulphonated and transition metal oxide doped polyaniline nanocomposite materials for supercapacitor electrodes