The　mechanism　of　Pt-M　(3d-metal)-enhanced　performance　compared　to　that　of　pure　platinum　as　the　cathode　catalyst　in　fuel　cells　is　not　entirely　clear.　In　this　paper,　a　DFT　calculation　is　applied　to　study　the　electronic　structures　of　Pt-Fe　alloys　and　ORR　(Oxygen　Reduced　Reaction)　on　Pt(1　1　1),　Pt-skinned　Pt3Fe(1　1　1)　and　Pt-skinned　PtFe3(1　1　1)　surfaces.　With　the　charge　transfer　between　Pt　and　Fe,　the　electronic　structure　thoroughly　differs　from　that　of　pure　Pt.　Consequently,　a　further　change　in　interaction　between　the　surface　and　adsorbates,　which　are　produced　during　the　ORR　process,　primarily　causes　the　improvement　in　ORR　performance.　When　used　as　a　catalyst,　the　Pt-skinned　Pt-Fe　alloy　surface　is　superior　to　the　Pt　surface　and　has　three　main　advantages:　(i)　a　more　appropriate　potential　for　each　electron　step　(closer　to　the　stand　reversible　potential),　(ii)　a　smaller　O-2　adsorption　energy,　and　(iii)　a　smaller　H2O　desorption　energy.　The　theoretical　results　also　show　that　the　Pt-skinned　PtFe3(1　1　1)　surface　has　obviously　higher　activity　than　the　Pt-skinned　Pt3Fe(1　1　1),　which　implies　that　activity　is　improved　with　the　increase　in　Fe　content.　This　work　provides　a　new　approach　to　understand　the　excellent　ORR　performance　of　Pt-M　alloys　and　design　other　non-noble　metal　catalysts.　(C)　2016　Elsevier　B.V.　All　rights　reserved.