Electrocatalyst concentration charge

Electrochemical NO sensors based on platinized or electrocatalyst-modified electrodes often in combination with a permselective and charged membrane for interference elimination were proposed. Although the catalytic mechanism is still unknown, it can be assumed that NO is co or dinative ly bound to the metal center of porphyrin or phthalocyanine moieties immobilized at the electrode surface. The coordinative binding obviously stabilizes the transition state for NO oxidation under formation of NO+. Typically, sub-pM concentrations of NO can be quantified using NO sensors enabling the detection of NO release from individual cells. 

The CT by oxidation of phthalocyanine zinc(II) (Zn Pc) in a Nafion film was also studied using a potential-step chronocoulospectrometry (PSCCS) technique [34]. Absorption spectra of Zn Pc/Nafion indicated the formation of the Zn Pc dimer, and the equilibrium constant between its monomer and dimer in the Nafion film was 75 M . The plots of bulk CT rate vs. total Zn Pc concentration gave a downwardly deviating curve, and the process was analyzed considering the equilibrium between the monomer and the dimer. The analysis result showed that CT takes place by physical displacement of the Zn Pc monomer with kp = 3.3 x 10 s and not by charge hopping, and that the contribution of the dimer to the CT is neghgible. The macrocyclic complexes such as [Co TTP]" " and Zn Pc are known to be an active electrocatalyst. The obtained CTs by [Co TPP] and Zn Pc should be taken into... 

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