FePc

Fig. 14. Relative resistivity of FePC as (----------) a glass, and (----------) in crystalline form.

Table 4. Influence of HMPA addition on cycle life of Li/Fe-phthalocyanine (FePc) cell ...

The first In situ MBS Investigation of molecules adsorbed on electrode surfaces was aimed primarily at assessing the feasibility of such measurements In systems of Interest to electrocatalysis (18). Iron phthalocyanlne, FePc, was chosen as a model system because of the availability of previous situ Mossbauer studies and Its Importance as a catalyst for O2 reduction. The results obtained have provided considerable Insight Into some of the factors which control the activity of FePc and perhaps other transition metal macrocycles for O2 reduction. These can be summarized as follows ... 

Significantly different ratios for the resonant absorption area. A, of the two doublets have been obtained for FePc preadsorbed at high loadings (> 15Z) upon changing the available surface area of the carbon. Specifically, a higher value of A2/Aj was found... 

Figure 6. situ Mossbauer spectra of 30% w/w FePc dispersed... 

These observations were regarded as providing evidence that doublet corresponds to FePc preadsorbed at monolayer coverages on Che carbon surface. 

The redox processes associated with the voltammetry for what was believed to be FePc adsorbed have been recently examined with In situ MBS In 1 M NaOH (19) Two strikingly different spectra... 

Figure 7. Cyclic voltammogram of 7% w/w FePc dispersed on Vulcan XC-72 carbon. The specimen was prepared by mixing the carbon with an FePc solution In pyridine and subsequently removing the solvent by boiling It off. The sample was then heat treated at 300°C In flowing He to remove coordinated pyridine. The cyclic voltammogram was obtained with the material In the form of a thin porous coating In 1 M NaOH at 25 C. Sweep rate 5 mV s (19).

Figure 8. Mossbauer spectrum of 7% w/w FePc dispersed on a high surface area carbon (XC-72). The specimen was prepared In the same fashion as described In the caption Fig. 6. The spectrum corresponds to the dry material (19).

Figure 10, In situ Mossbauer spectra for a Vulcan XC-72 carbon electrode containing FePc obtained at 0.0 V vs. Hg/Hg0,0H, (Figure k) and at -1.05 V vs. Hg/HgO,OH, (Figure B)(19).

For example, the a- and /3-phases of FePc, which correspond to co-facial structures of the macrocycles, were studied and compared. The stmcmre of MPcs (M = metal)... 

Figure 11.13 Linear cyclic voltammograms of different carbon-supported catalysts recorded in an 02-saturated electrolyte (0.5 M H2SO4) (1) Pt/C catalyst (2) Pt/C catalyst in the presence of 1.0 M methanol (3) FePc/C catalyst (4) FePc/C catalyst in the presence of 1.0 M methanol (temperature 20 °C, scan rate 5 mV s rotation speed 2500 rev min ).

Figure 11.14 E versus time curve recorded during the ORR on a FePc/C gas diffusion electrode j = —25 mAcm ). The FePc electrode was fed with ambient air without any convection (temperature 20 °C) [Baranton et al., 2005].

Figure 11.16 Schematic orientation of the planar FePc molecules in the crystallographic cell (a) a-FePc calculated from the data obtained by Ballirano and co-workers [Ballirano et al., 1998] (b) /3-FePc calculated from the data obtained by Kimer and co-workers [Kimer et al., 1976],...

For /3-FePc, only one Tafel slope could be observed, with a value close to — 63 mV/decade. 

These facts indicate that two mechanisms are involved, depending on the electrode potential in the case of a-FePc whereas only one mechanism seems to be involved in the case of /3-FePc. 

Figure 11.17 Linear cyclic voltammograms of a-FePc/C (-----) and /3-FePc (- - -)...

Baranton S, Coutanceau C, Gamier E, Leger JM. 2006. How does a-FePc catalysts dispersed onto high specific surface carbon support work towards oxygen reduction reaction (orr) J Electroanal Chem 590 100-110. 

The FePcY-PDMS supramolecular catalyst resembles the architecture of natural enzymes. In this system the PDMS membrane takes over the role of the phospholipid double layer likewise, the zeolite imitates the protein and the FePc complex the Fe-protoporphyrin. Zeolite-encaged Cu-histidine complexes were also studied as mimics of natural Cu-enzyme complexes.173... 

FepA FepB FepD, FepG FepC Enterochelin Earhart, 1996... 

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