Photocatalytic　H2　evolution　has　been　regarded　as　a　promising　technology　to　alleviate　the　energy　crisis.　Designing　graphitic　carbon　nitride　materials　with　a　large　surface　area,　short　diffusion　paths　for　electrons,　and　more　exposed　reactive　sites　are　beneficial　for　hydrogen　evolution.　In　this　study,　a　facile　method　was　proposed　to　dope　P　into　a　graphitic　carbon　nitride　framework　by　calcining　melamine　with　2-aminoethylphosphonic　acid.　Meanwhile,　PCN　nanosheets　(PCNSs)　were　obtained　through　a　thermal　exfoliation　strategy.　Under　visible　light,　the　PCNS　sample　displayed　a　hydrogen　evolution　rate　of　700　μmol·g−1·h−1,　which　was　43.8-fold　higher　than　that　of　pure　g-C3N4.　In　addition,　the　PCNS　photocatalyst　also　displayed　good　photostability　for　four　consecutive　cycles,　with　a　total　reaction　time　of　12　h.　Its　outstanding　photocatalytic　performance　was　attributed　to　the　higher　surface　area　exposing　more　reactive　sites　and　the　enlarged　band　edge　for　photoreduction　potentials.　This　work　provides　a　facile　strategy　to　regulate　catalytic　structures,　which　may　attract　great　research　interest　in　the　field　of　catalysis.　©　2024　by　the　authors.