Biomass　derived　carbons　via　hydrothermal　carbonization　(HTC)　are　critically　important　for　different　applications　due　to　their　low　cost,　eco-friendly　properties,　light　weight　and　potential　for　the　catalysis　research　field.　However,　standard　HTC　carbons　commonly　present　amorphous　and　spherical　morphology　with　low　surface　areas　and　large　particle　size.　Here　we　report　a　2D　morphology　of　crystalline　carbons　via　a　HTC　method　by　employing　the　biomolecule　guanine　and　diverse　carbohydrates　(glucose,　fructose　and　cellulose)　as　carbon　precursors.　Importantly,　the　addition　of　guanine　to　the　HTC　process　plays　a　significant　role　in　producing　the　2D-morphology　of　carbon　materials　from　the　diverse　carbohydrates.　Hierarchical　porous　nitrogen-doped　carbons　with　high　surface　areas　up　to　974　m2　g-1　and　nitrogen　contents　as　high　as　2.39　at%　are　made　by　further　high　temperature　carbonization.　The　current　2D　carbons　are　found　to　be　highly　active　toward　the　oxygen　reduction　reaction　(ORR)　with　a　rather　positive　half-wave　potential　of　0.87　V　(vs.　the　RHE)　and　a　large　limiting　current　density　of　5.9　mA　cm-2.　These　catalysts　outperform　most　other　equivalent　benchmarks　as　well　as　Pt-based　electrocatalysts,　meanwhile　being　efficient　for　the　hydrogen　evolution　reaction　(HER)　with　a　very　low　overpotential　of　0.35　V　to　achieve　10　mA　cm-2　in　alkaline　medium.　It　is　expected　that　our　synthetic　protocol　can　be　extended　to　various　bio-nucleobases,　yielding　all-sustainable　bio-based　electrocatalysts　with　a　tunable　structure,　elemental　composition,　porosity　and　electronic　properties.　©　2017　The　Royal　Society　of　Chemistry.