Impedance study of electropolymerized films of polyNi(II)-macrocycles

Unveiling the structure of polytetraruthenated nickel porphyrin by Raman spectroelectrochemistry

The structure of polytetraruthenated nickel porphyrin was unveiled for the first time by electrochemistry, Raman spectroelectrochemistry, and a hydroxyl radical trapping assay. The electrocatalytic active material, precipitated on the electrode surface after successive cycling of [NiTPyP{Ru(bipy)2Cl}4](4+) species in strong aqueous alkaline solution (pH 13), was found to be a peroxo-bridged coordination polymer. The electropolymerization process involves hydroxyl radicals (as confirmed by the characteristic set of DMPO/(•)OH adduct EPR peaks) as reaction intermediates, electrocatalytically generated in the 0.80-1.10 V range, that induce the formation of Ni-O-O-Ni coordination polymers, as evidenced by Raman spectroelectrochemistry and molecular modeling studies. The film growth is halted above 1.10 V due to the formation of oxygen gas bubbles.

The influence of gold nanoparticles on the electroactivity of nickel tetrasulfonated phthalocyanine

We report on the electrodeposition of gold nanoparticles ( AuNPs ) on a glassy carbon electrode (GCE) followed by deposition of nickel tetrasulfonated phthalocyanine ( NiTSPc ) film by electropolymerization (poly- NiTSPc -GCE) to form Poly- NiTSPc / AuNPs -GCE. The presence of the gold nanoparticles caused a lowering of the anodic and cathodic peak separation (ΔE p ) of ferricyanide from 126 mV on poly- NiTSPc to 110 mV on poly- NiTSPc / AuNPs . The electrooxidation of nitrite improved on modified electrodes compared to GCE, with the latter giving E p = 0.78 V and the modified electrodes gave E p = 0.62 V or 0.61 V. Poly- NiTSPc / AuNPs -GCE had higher currents compared to poly- NiTSPc -GCE. This indicates the enhancement effect caused by the AuNPs . Electrochemical impedance spectroscopy and chronoamperometric studies also showed that poly- NiTSPc / AuNPs -GCE was a better electrocatalyst than poly- NiTSPc -GCE or AuNPs -GCE.

Single walled carbon nanotubes functionalized with nickel phthalocyanines: effects of point of substitution and nature of functionalization on the electro-oxidation of 4-chlorophenol

In this work we report on electrochemical behavior of nickel phthalocyanine derivatives tetrasubstituted peripherally and non-peripherally with hydroxy and used to modify single walled carbon nanotubes. Nickel phthalocyanine complex octasubstituted at the peripheral positions with hydroxy groups was also used to modify single walled carbon nanotubes. Nickel phthalocyanine complex tetrasubstituted with amino groups at peripheral position was covalently and non-covalently linked to single walled carbon nanotubes. All the conjugates of nickel phthalocyanine derivatives with single walled carbon nanotubes were used for the electro oxidation of 4-chlorophenol. The nickel phthalocyanine octabsubstituted with hydroxy groups at the non-peripheral positions gave the best current response and the best resistance against electrode fouling for the oxidation of 4-chlorophenol.

CHARACTERIZATION OF QUANTUM DOTS, SINGLE WALLED CARBON NANOTUBES AND NICKEL OCTADECYLPHTHALOCYANINE CONJUGATES

In this work nickel octadecylphthalocyanine (NiPc(C10H21)8) and cadmium telluride quantum dots (QDs) capped with thioglycolic acid (TGA) are adsorbed on single walled carbon nanotubes (SWCNT) to form NiPc(C10H21)8 -SWCNT-QDs conjugate. X-ray photoelectron, ultra violet/visible and Raman spectroscopies are used to characterize the conjugate. SWCNT, poly- Ni(O)Pc(C10H21)8 , NiPc(C10H21)8 -SWCNT and NiPc(C10H21)8 -SWCNT-QDs complexes are used to modify glassy carbon electrode (GCE) and used for the electro-oxidation of pentachlorophenol as a test molecule. NiPc(C10H21)8 -SWCNT-QDs electrode gave the best detection current for pentachlorophenol.