Photocatalytic　water　splitting　with　simultaneous　degradation　of　organic　pollutants　is　an　effective　strategy　to　alleviate　the　increasingly　serious　energy　and　environmental　crisis.　However,　the　photocatalytic　activity　is　restricted　by　the　high　charge　recombination　rate　and　limited　sunlight　utilization.　Herein,　black　phosphorus　(BP)　with　a　broad　sunlight　response　range　was　utilized　as　a　photosensitizer　to　enhance　the　photocatalytic　performance　of　the　Au/carbon　nitride　(CN)　heterostructure.　The　as-prepared　BP/Au/CN　exhibited　a　significantly　enhanced　H2　generation　rate　of　1400.8　mu　mol　h(-1)　g(-1)　under　UV-vis　light　irradiation,　which　is　almost　70　times　higher　than　that　of　bare　CN　and　BP/CN　and　2　folds　higher　than　that　of　the　Au/CN　heterojunction.　Specifically,　the　optimal　BP/Au/CN　sample　presented　a　waste-to-hydrogen　pro-　duction　rate　of　195.8　mu　mol　h(-1)　g(-1)　with　the　degradation　of　bisphenol　A,　verifying　the　synergistic　effect　of　the　ternary　heterojunction.　The　photocatalytic　mechanism　was　systematically　studied　by　the　combination　of　experiments　and　theoretical　calculations.　The　improved　photocatalytic　performance　was　derived　from　the　overall　sunlight　absorption　ability　of　BP,　effective　electron　transfer　media　and　plasmonic　character　of　Au　nanoparticles,　as　well　as　the　matched　work　function　and　strong　interaction　of　the　three　components.　A　unidirectional　electron　transfer　from　BP　to　Au　and　then　to　CN　was　established,　which　effectively　improved　the　charge　transfer　capability,　resulting　from　the　appropriate　Ohmic　contact　of　Au　and　BP　and　the　Schottky　barrier　constructed　in　Au/CN　hybrid.