摘要
In recent years,Fe-N-C catalyst is particularly attractive due to its high oxygen reduction reaction(ORR)activity and low cost for proton exchange membrane fuel cells(PEMFCs).However,the durability problems still pose challenge to the application of Fe-N-C catalyst.Although considerable work has been done to investigate the degradation mechanisms of Fe-N-C catalyst,most of them are simply focused on the active-site decay,the carbon oxidation,and the demetalation problems.In fact,the 2e−pathway in the ORR process of Fe-N-C catalyst would result in the formation of H2O2,which is proved to be a key degradation source.In this paper,a new insight into the effect of potential on degradation of Fe-N-C catalyst was provided by quantifying the H2O2 intermediate.In this case,stability tests were conducted by the potential-static method in O2 saturated 0.1 mol/L HClO4.During the tests,H2O2 was quantified by rotating ring disk electrode(RRDE).The results show that compared with the loading voltage of 0.4 V,0.8 V,and 1.0 V,the catalysts being kept at 0.6 V exhibit a highest H2O2 yield.It is found that it is the combined effect of electrochemical oxidation and chemical oxidation(by aggressive radicals like H2O2/radicals)that triggered the highest H2O2 release rate,with the latter as the major cause.
基金
The work was supported by the Thirteenth National Key Point Research and Invention Program(No.2016YFB0101302)。
