Development　of　graphene-like　nanocarbons　with　a　3D　interlinked　porous　structure　has　gained　much　interest　due　to　their　synergetic　merits　combining　2D　morphology　with　porous　architectures.　Herein,　a　novel　kind　of　graphene-like　nanocarbon　is　prepared　via　a　simple,　relatively　cost-efficient　and　scalable　strategy,　by　using　the　biomolecule　guanine　as　the　precursor　combined　with　a　facile　CO2　activation　procedure.　The　as-prepared　materials　not　only　have　in　situ　high-level　nitrogen　doping　and　defect-enriched　properties,　but　also　possess　a　unique　3D　architecture　constituted　by　the　interconnection　of　ultrathin　and　curly　carbon　nanosheets.　These　synergistic　advantages　of　a　3D　hierarchically　porous　structure,　a　large　surface　area,　a　high　content　of　active　nitrogen　species,　abundant　defect　sites　and　a　unique　graphene-like　architecture,　thus　endow　the　materials　with　excellent　catalytic　activity,　methanol　immunity　and　long-term　stability　for　the　ORR　under　both　acidic　and　alkaline　conditions,　very　comparable　and　even　superior　to　those　of　a　Pt/C　catalyst.　This　work　is　expected　to　provide　a　facile　but　efficient　strategy　for　large-scale　preparation　of　graphene-based　materials,　and　meanwhile　inspire　an　idea　for　developing　more　efficient　electrocatalysts.　©　2019　The　Royal　Society　of　Chemistry.