Photoelectrochemical　water　splitting　fulfils　sustainable　goal　in　the　renewable　H2　fuel　production　by　storage　of　solar　energy　through　chemical　bonds.　In　the　system,　a　rational　design　of　a　photoanode　is　the　key　to　achieve　an　efficient　solar　water　splitting,　since　the　sluggish　kinetic　of　oxygen　evolution.　Herein,　polymeric　carbon　nitride　based　visible-light　sensitive　photoanodes　are　achieved　with　the　gradient　sulfur　doping　along　the　films.　Subsequently,　a　gradual　variation　of　the　bandgap　is　formed.　Therefore,　on　one　hand,　visible　light　absorption　of　the　films　is　increased　up　to　2.55　eV.　On　the　other　hand,　charge　separation　and　transfer　are　promoted　by　virtue　of　the　gradually　varied　electronic　properties.　As　a　result,　the　architecture　of　photoanode　profits　for　water　oxidation　and　leads　the　optimal　photocurrent　density　ca.　110　μA/cm2　at　1.23　V　vs　reversible　hydrogen　electrode.　©　2019　Elsevier　B.V.