Teethlike　homojunctions　BiOCl　(001)　nanosheets　with　tunable　photoresponse　were　constructed　by　selective　etching　with　triethanolamine　and　allowed　fast　charge　separation　across　the　interfaces　to　facilitate　photocatalysis.　The　unique　microstructure　exhibits　a　superior　photocatalytic　activity　that　can　be　ascribed　to　the　combined　interaction　of　the　high　UV/vis　light　harvest,　high　photogenerated　charge　separation　efficiency,　and　the　fast　interfacial　charge-transfer　rate　based　on　the　unique　homogeneous　topotactic　structure.　We　believe　that　the　creation　of　this　new　model　junction　may　be　a　great　aid　in　the　design　and　preparation　of　efficient　semiconductor　based　photocatalysts　and　a　new　understanding　of　the　essential　relation　between　the　junction　and　the　photocatalytic　activity.