First　principles　calculation　is　performed　to　study　the　co-adsorption　behaviors　of　O2　and　CO2　on　δ-Pu(100)　surface　by　using　a　slab　model　within　the　framework　of　density　functional　theory　(DFT).　The　results　demonstrate　that　the　most　favorable　co-adsorption　configurations　are　Tv-C4O7　and　Tp1-C2O8,　with　adsorption　energy　of　-17.296　eV　and　-23.131　eV　for　CO2-based　and　O2-based　system,　respectively.　The　C　and　O　atoms　mainly　interact　with　the　Pu　surface　atoms.　Furthermore,　the　chemical　bonding　between　C/O　and　Pu　atom　is　mainly　of　ionic　state,　and　the　reaction　mechanism　is　that　C　2s,　C　2p,　O　2s,　and　O　2p　orbitals　overlap　and　hybridize　with　Pu　6p,　Pu　6d,　and　Pu　5f　orbital,　resulting　in　the　occurrence　of　new　band　structure.　The　adsorption　and　dissociation　of　CO2　molecule　are　obviously　promoted　by　preferentially　occupying　adsorbed　O　atoms,　therefore,　a　potential　CO2　protection　mechanism　for　plutonium-based　materials　is　that　in　CO2　molecule　there　occurs　complete　dissociation　of　CO2　→　C　+　O　+　O,　then　the　dissociated　C　atom　combines　with　O　atom　from　O2　dissociation　and　produces　CO,　which　will　inhibit　the　O2　from　further　oxidizing　Pu　surface,　and　slow　down　the　corrosion　rate　of　plutonium-based　materials.　©　2021　Chinese　Physical　Society　and　IOP　Publishing　Ltd.