Electrochemical and fuel cell evaluation of Co based catalyst for oxygen reduction in anion exchange polymer membrane fuel cells

Abstract: Co based catalyst were evaluated for oxygen reduction (ORR) in liquid KOH and alkaline anion exchange membrane fuel cells (AAEMFCs). In liquid KOH solution the catalyst exhibited good performance with an onset potential 120mV more negative than platinum and a Tafel slope of ca. 120mVdec−1. The hydrogen peroxide generated, increased from 5 to 50% as the electrode potential decreased from 175 to −300mV vs. SHE. In an AAEMFC environment, one catalyst (GP2) showed promising performance for ORR, i.e. at 50mAcm−2 the differences in cell potential between the stable performance for platinum (more positive) and cobalt cathodes with air and oxygen, were only 45 and 67mV respectively. The second catalyst (GP4) achieved the same stable power density as with platinum, of 200 and 145mWcm−2, with air at 1bar (gauge) pressure and air (atm) cathode feed (60°C), respectively. However the efficiency was lower (i.e. cell voltage was lower) i.e. 40% in comparison to platinum 47.5%. [Copyright &y& Elsevier]