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In a solid polymer fuel cell series, various circumstances can result in a fuel cell being driven into voltage reversal by other cells in the series stack. For instance, cell voltage reversal can occur if that cell receives an inadequate supply of fuel (for example, fuel starvation). In order to pas

In a solid polymer fuel cell series, various circumstances can result in a fuel cell being driven into voltage reversal by other cells in the series stack. For instance, cell voltage reversal can occur if that cell receives an inadequate supply of fuel (for example, fuel starvation). In order to pass current during fuel starvation, reactions other than fuel oxidation may take place at the fuel cell anode, including water electrolysis and oxidation of anode components. The latter may result in significant degradation of the anode. Such fuel cells can be made more tolerant to cell reversal by promoting water electrolysis over anode component oxidation at the anode. This can be accomplished by enhancing the presence of water in the anode catalyst layer through modifications to the anode structure or anode composition near or in the catalyst layer. For instance, water electrolysis during voltage reversal is promoted through the use of different or additional ionomer, polytetrafluoroethylene, or graphite in the anode catalyst layer, or through the use of certain sublayers between the anode catalyst layer and the anode substrate.

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In a solid polymer fuel cell series, various circumstances can result in a fuel cell being driven into voltage reversal by other cells in the series stack. For instance, cell voltage reversal can occur if that cell receives an inadequate supply of fuel (for example, fuel starvation). In order to pas

In a solid polymer fuel cell series, various circumstances can result in a fuel cell being driven into voltage reversal by other cells in the series stack. For instance, cell voltage reversal can occur if that cell receives an inadequate supply of fuel (for example, fuel starvation). In order to pass current during fuel starvation, reactions other than fuel oxidation may take place at the fuel cell anode, including water electrolysis and oxidation of anode components. The latter may result in significant degradation of the anode. Such fuel cells can be made more tolerant to cell reversal by promoting water electrolysis over anode component oxidation at the anode. This can be accomplished by enhancing the presence of water in the anode catalyst layer through modifications to the anode structure or anode composition near or in the catalyst layer. For instance, water electrolysis during voltage reversal is promoted through the use of different or additional ionomer, polytetrafluoroethylene, or graphite in the anode catalyst layer, or through the use of certain sublayers between the anode catalyst layer and the anode substrate. aim 1, wherein X in general formula (1), (4) or (5) is substituted by a halogen, an alkyl group, an alkoxyl group, an aralkyl group, a nitro group, a cyano group, an amino group, an aryl group, or a heterocyclic group. 3. An electroluminescent device comprising a pair of electrodes and an organic compound layer interposed between said electrodes, said organic compound layer comprising an organic compound represented by the following general formula (1), (4) or (5): wherein X is fluorenone or a heterocyclic group, said heterocyclic group being selected from divalent moieties of compounds selected from the group consisting of carbazole, dibenzofuran, dibenzothiophene, oxazole, oxadiazole and thiadiazole, wherein three groups among Ar1,Ar2,Ar3,and Ar4are each a substituted or unsubstituted fluorenyl group having one sp3fluorene ring carbon, and the remainder is a substituted or unsubstituted aryl group wherein X is fluorenone or a heterocyclic group, said heterocyclic group being selected from divalent moieties of compounds selected from the group consisting of carbazole, dibenzofuran, dibenzothiophene, oxazole, oxadiazole and thiadiazole; Ar1and Ar2are each a substituted or unsubstituted aryl group; R1,R2,R3and R4are each independently a hydrogen or halogen atom, or a substituted or unsubstituted alkyl, alkoxyl, or aryl group; and R5and R6are each independently a hydrogen or halogen atom, a nitro or cyano group, or a substituted or unsubstituted alkyl, alkoxyl, aryl, or carbonyl group; wherein X is fluorenone or a heterocyclic group, said heterocyclic group being selected from divalent moieties of compounds selected from the group consisting of carbazole, dibenzofuran, dibenzothiophene, oxazole, oxadiazole and thiadiazole; R7,R8,R9,R10,R11,R12,R13,and R14are each independently a hydrogen or halogen atom, or a substituted or unsubstituted alkyl, alkoxyl, or aryl group; each of R15,R16,R17and R18is independently a hydrogen or halogen, nitro or cyano, or a substituted or unsubstituted alkyl, alkoxyl, aryl, amino or carbonyl group. 4. An electro-luminescent device according to claim 3, wherein X in general formula (1), (4) or (5) is substituted by a halogen, an alkyl group, an alkoxyl group, an aralkyl group, a nitro group, a cyano group, an amino group, an aryl group, or a heterocyclic group.