Artificial　photosynthesis　employing　solar　energy　is　one　of　the　best　means　of　reaching　a　sustainable　energy　cycle,　in　which　water　is　oxidized　to　oxygen　and　supplies　electrons　for　fuel　generation.　The　development　of　suitable　oxygen　evolution　materials　driven　by　sunlight　is　hence　the　most　challenging　research　topic　in　the　field　of　photocatalysis.　Herein,　photocatalytic　O2　production　from　water　at　a　rate　of　22.6　μmol　h−1　was　performed　by　using　a　pyrene-based　organic　molecule　constructed　through　the　Ullmann　coupling　reaction.　Its　significantly　improved　light-harvesting　ability　and　notably　accelerated　separation　and　transfer　of　photogenerated　charges　enhanced　the　O2　evolution　efficiency.　This　study　highlights　the　structural　design　of　organic　molecules　applied　to　photocatalytic　water　splitting.　©　2019　Wiley-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim