Investigations On The High Performance ORR Catalyst Used For Fuel Cell

The fuel cell is a kind of environmental protection chemical power supply with a high specific energy.The performance of the oxygen reduction reaction（ORR）catalyst plays an important role in the performance of the fuel cell.In this paper,the active sites of ORR catalyst were designed by DFT calculation.Given the designed five coordinated transition metal manganese/iron nitrogen carbon（Mn/Fe-N-C）ORR catalytic active site,Mn-N-C/G catalyst and Mn/Fe-N-C/G catalyst were synthesized on a monolayer graphene substrate by using the self-developed tailoring—self-assembly—reconstruction vapor deposition（TSRVD）technic with manganese phthalocyanine and iron phthalocyanine as the precursors.The TSRVD process parameters were studied systematically.The morphology and structure of Mn-N-C/G-30 catalyst were characterized by SEM,TEM,XRD,Raman,and XPS.The ORR activity of the catalyst was studied by CV,LSV,Tafel,EIS,and chronoamperometry.DFT calculation shows that the ORR catalytic performance of the five coordination Mn-N active site embedded in the carbon six-membered ring structure is better than that of Pt.The leaf-like Mn-N-C/G-30 catalyst with Mn-N5 active sites was synthesized by the TSRVD.The electrochemical test results showed that the ORR performance of the Mn-N-C/G-30 catalyst in 25℃and 0.1 MKOH solution was 0.97V（higher than that of commercial Pt/C,0.94 V）and the current density at 0.88 V was1.4 mA·cm^-2(higher than that of commercial Pt/C,1.3 mA·cm^-2).Meanwhile it had better stability.Mn/Fe-N-C/G catalyst was synthesized by the TSRVD process with the mixture of manganese phthalocyanine and iron phthalocyanine as the precursor.The effect of the TSRVD process parameters on the performance of the Mn/Fe-N-C/G catalyst was studied by the orthogonal experiment.The results show that the optimum synthesis parameters are:the heating temperature of the precursor is 450℃,the crystallization temperature of the catalyst is 110℃,and the mixing ratio of manganese phthalocyanine and iron phthalocyanine is 2:1.