Abstract
Pt3M (M = 3d transition metals) supported on oxygen-doped graphene as an electrocatalyst for oxygen reduction was investigated using the periodic density functional theory-based computational method. The results show that oxygen prefers to adsorb on supported Pt3M in a bridging di-oxygen configuration. Upon reduction, the O–O bond breaks spontaneously and the oxygen adatom next to the metal–graphene interface is hydrogenated, resulting in co-adsorbed O* and OH* species. Water formation was found to be the potential-limiting step on all catalysts. The activity for the oxygen reduction reaction was evaluated against the difference of the oxygen adsorption energy on the Pt site and the M site of Pt3M and the results indicate that the oxygen adsorption energy difference offers an improved prediction of the oxygen reduction activity on these catalysts. Based on the analysis, Pt3Ni supported on oxygen-doped graphene exhibits an enhanced catalytic performance for oxygen reduction over Pt4.
Highlights
Proton-exchange membrane fuel cells (PEMFCs) can directly convert the chemical energy stored in hydrogen and oxygen into electricity [1,2,3], but their adoption for practical application as electrocatalysts is hindered by the high price and limited supply of platinum [4,5,6]
Among difference of O*, O* adsorbed on the interfacial site became less stable, resulting in a similar trend to all the O-doped graphene (OG)–Pt3 Ms, Ni exhibited the largest decrease in the reaction free energy, and thereby, the limiting that of the OH* species
The present analysis demonstrated that oxygen adsorption energy alone is not effective in predicting oxygen reduction reaction (ORR) reactivity
Summary
Proton-exchange membrane fuel cells (PEMFCs) can directly convert the chemical energy stored in hydrogen and oxygen into electricity [1,2,3], but their adoption for practical application as electrocatalysts is hindered by the high price and limited supply of platinum [4,5,6]. Graphene-supported Pt and metal alloy catalysts have been studied for the oxygen reduction process [24,25,26]. Catalyst and/or work synergistically thegraphene active components to graphene materials. These oxygen-derived defectwith sites in may form the promote the reactions. The use of graphene oxides either alone or as a support in the anchor sites for the active catalyst and/or work synergistically with the active components to promote electrode has attracted extensive attention [6,33,34,35]. We compared the effect of transition metals on the ORR mechanism and activity. O , OH,Ni and adsorption energies, as well as the ORR mechanism, we identified Ni as the most effective modifier
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