Coupling　molybdenum-based　materials　with　carbon　is　an　effective　strategy　to　improve　the　hydrogen　evolution　reaction　(HER)　performance.　However,　achieving　the　desired　surface-active　sites　by　regulating　the　catalyst＇s　morphology　presents　a　challenge.　Here,　we　present　a　novel　approach　using　guanosine　as　an　assisting　agent　to　synthesize　core-shell　Mo2N/Mo2C/C　composites.　By　utilizing　guanosine　in　combination　with　ammonium　heptamolybdate,　we　induce　the　formation　of　new　hierarchical　Mo-based　structures　through　intrinsic　self-regulating　mechanisms.　The　presence　of　rich　interactions　between　guanosine　molecules,　such　as　hydrogen　bonding　and　pi-pi　stacking,　plays　a　pivotal　role　in　achieving　this　successful　outcome.　Notably,　a　core-shell　spherical　MoO2/CN　polymer　was　formed　when　using　an　optimal　amount　of　guanosine.　By　pyrolysis　at　800　degrees　C,　this　was　transformed　into　the　core-shell　Mo2N/Mo2C/C　composite.　The　unexpected　core-shell　structure　was　elucidated　through　ex　situ　XRD　and　SEM　characterization,　highlighting　the　dominance　of　carbon　in　the　outer　shells　and　molybdenum-rich　phases　in　the　core.　The　synthesized　Mo2N/Mo2C/C　composites　exhibit　a　low　overpotential　of　only　79　mV　under　alkaline　conditions,　which　is　comparable　to　that　of　commercially　available　Pt/C　catalysts.　Our　study　offers　a　promising　route　for　developing　noble-metal-free　catalysts　with　enhanced　HER　performance,　contributing　to　the　advancement　of　green　hydrogen　generation　technologies.