Polyphthalocyanines Conductivity

Polymeric dyes, such as the polymeric phthalocyanines, become more conducting as the degree of polymerization increases. This is demonstrated in Fig. 5 for polymeric Fe- and Co-polyphthalocyanines 65>. 

Fig. 5. Relationship between thermal activation energy and dark conductivity AEn=f (log od).------ Fe-polyphthalocyanine .Co-polyphthalocyanine...

Table 10. Relation between catalytic activity of H2O2 decomposition (given in time 50 [min] necessary for a decomposition of 50% H202) and dark conductivity of Co-polyphthalocyanines (from Ref. 5))...

Moreover, the conductivity, and hence the catalytic decomposition of hydrogen peroxide, has been observed to influence the stability of the oxygen electrode. The stability of phthalocyanine catalysts is a decisive factor for the practical applicability of organic catalysts in fuel cells operating in an acid medium. This is therefore a very important observation. The observed disturbance of the delocalization of the n electrons (rubiconjugation) in Fe-polyphthalocyanines, in addition to the correlation between conductivity on the one hand, and electrocatalysis and catalytic decomposition of hydrogen peroxide on the other, leads to a special model of the electroreduction of oxygen on phthalocyanines. The model... 

Table 11. Relation between electrocatalytic activity (given in the potential 20 measured at a current density of 20 mA/cm2) and conductivity in Fe-polyphthalocyanine samples (from Ref. e5>)...

Fe-polyphthalocyanine [sample No] Electrocatalytic activity y>20 [mV] Dark conductivity ctd [ohm-tcm-1]... 

Yet it will be necessary to look for systems having higher conductivities, since a Peltier refrigerator, for example, would become competitive in its power consumption only above an effectivity of Gx = 6 x 10-3 deg-1. It is probable that this aim will be reached. Table 12 shows a Cu-polyphthalocyanine sample with a remarkably favorable Gx value of about 5 x 10 4 deg-1. 

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