Hydrogen　peroxide　(H2O2)　electrosynthesis　using　metal-free　carbon　materials　via　the　2e(-)　oxygen　reduction　pathway　has　sparked　considerable　research　interest.　However,　the　scalable　preparation　of　carbon　electrocatalysts　to　achieve　satisfactory　H2O2　yield　in　acidic　media　remains　a　grand　challenge.　Here,　we　present　the　design　of　a　carbon　nanoreactor　series　that　integrates　precise　O/N　codoping　alongside　well-regulated　geometric　structures　targeting　high-efficiency　electrosynthesis　of　H2O2.　Theoretical　computations　reveal　that　strategic　N/O　codoping　facilitates　partial　electron　transfer　from　C　sites　to　O　sites,　realizing　electronic　rearrangement　that　optimizes　C-site　adsorption　of　*OOH.　Concurrently,　the　O-O　bond　in　*OOH　is　strengthened　by　charge　transfer　from　antibonding　to　pi-orbitals,　stabilizing　the　O-O　bond　and　preventing　its　dissociation.　The　carbon　nanoreactor　with　a　hollow　bowl　geometry　also　facilitates　the　mass　transport　of　O-2　and　H2O2,　achieving　an　H2O2　selectivity　of　96%　in　acidic　media.　Furthermore,　a　flow　cell　integrated　with　the　refined　nanoreactor　catalyst　achieves　an　impressive　H2O2　production　rate　of　2942.4　mg　L-1　h(-1),　coupled　with　stable　operation　of　nearly　80　h,　surpassing　the　state-of-the-art　metal-free　analogs.　The　feasibility　of　the　electro-synthesized　H2O2　is　further　demonstrated　to　be　highly　efficient　in　wastewater　remediation.