Comparative characteristics of cathodes with different catalytic systems in hydrogen–oxygen and hydrogen–air fuel cells with proton-conducting polymer electrolyte

Resumo

The characteristics of low-temperature hydrogen–oxygen (air) fuel cell (FC) with cathodes based on the 50 wt % PtCoCr/C and 40 wt % Pt/CNT catalysts synthesized on XC72 carbon black and carbon nanotubes (CNT) are compared with the characteristics of commercial monoplatinum systems 9100 60 wt % Pt/C and 13100 70% Pt/C HiSPEC. It is shown that the synthesized catalysts exhibit a high mass activity, which is not lower than that of commercial Pt/C catalysts, a high selectivity with respect to the oxygen reduction to water, and a significantly higher stability. The characteristics of PtCoCr/C and Pt/CNT were confirmed by testing in the hydrogen—oxygen FCs. However, when air was used at the cathode, especially in the absence of excessive pressure, a voltage of FC with the cathode based on PtCoCr/XC72 is lower as compared with the commercial systems. Probably, this is associated with the transport limitations in the structure of trimetallic catalyst synthesized on XC72 carbon black due to the absence of mesopores. This drawback was eliminated to a large extent by raising the volume of mesopores as a result of application of mixed support (XC72 + CNT) and the use of only CNT for the synthesis of the monoplatinum catalyst. However, this did not eliminate another drawback, namely, a low platinum utilization coefficient in the cathode active layer as compared with that measured under the model conditions in the 0.5 M Н₂SO₄ solution. Therefore, further research is required to improve the structure of the catalytic systems, which are synthesized both on carbon black and nanotubes, while maintaining their high stability and selectivity.