Presented　here　is　a　facile,　sustainable　and　green　method　for　the　synthesis　of　N-doped　carbon　microspheres/nanosheets　via　hydrothermal　carbonization　(HTC)　of　the　selected　bioprecursor　guanosine.　The　morphology　of　such　carbons　presents　a　hierarchical　microstructure　consisting　of　carbon　microspheres　and　carbon　nanosheets　with　a　relatively　disordered　but　mainly　sp2　hybridized　graphitic　structure.　Control　experiments　indicate　that　the　formation　of　carbon　microspheres　was　mainly　related　to　the　HTC　process　of　the　ribose　component　in　guanosine,　while　the　carbon　nanosheets　likely　originated　because　of　the　self-templating　effect　of　the　guanine　component　in　guanosine.　This　kind　of　HTC　product　(Go-HTC-1000)　properly　compensates　for　the　disadvantages　of　the　ribose-based　counterpart　(such　as　a　monotonously　microporous　structure　and　non-nitrogen　doped　nature)　and　the　guanine-based　counterpart　(such　as　a　low　specific　surface　area　and　low　HTC　carbon　yield),　leading　to　the　formation　of　a　completely　new　carbon　with　in　situ　high-level　nitrogen　doping,　moderately　defective　structure　and　developed　hierarchically　porous　texture.　Owing　to　such　unique　morphological　and　structural　features,　it　is　expected　to　be　superior　in　several　catalytic　reactions.　When　representatively　used　as　an　electrocatalyst　for　the　oxygen　reduction　reaction　(ORR),　it　exhibits　superior　performance　with　a　very　positive　half-wave　potential　of　0.850　V　(vs.　RHE)　comparable　to　that　of　the　Pt/C　catalyst　(0.855　V)　and　excellent　stability.　When　serving　as　an　electrode　material　for　vanadium　redox　reflow　batteries　(VRFBs),　it　shows　significantly　improved　performances　in　both　positive　and　negative　reactions　compared　to　pristine　graphite　felt　(GF),　performing　well　at　various　current　densities　ranging　from　100　mA　cm-2　to　500　mA　cm-2　and　achieving　high　energy　efficiency　and　good　rate　performance.　The　work　is　believed　to　inspire　a　new　perspective　for　the　facile　but　efficient　fabrication　of　novel　carbon-based　materials　with　high　added　values.　This　journal　is　©　The　Royal　Society　of　Chemistry.