Bismuth　oxychloride　micro-sheets　with　rich　oxygen　vacancies　(BiOCl-OV)　are　firstly　prepared　through　a　surfactant　assisted　solvothermal　method.　Due　to　the　selective　surfactant　adsorption,　the　as-prepared　BiOCl-OV　exposes　high　percentage　{0　0　1}　facets.　Moreover,　the　ion-exchange　process　not　only　introduces　Br　atoms　but　also　creates　cavities　in　crystal　structure　of　the　Br　doped　BiOCl-OV　(Br-BiOCl-OV).　When　used　as　photocatalyst　for　N2　photo-fixation,　the　optimized　Br-BiOCl-OV　demonstrates　an　ammonia　producing　rate　of　6.3　μmol　h−1　under　visible　light　irradiation,　which　is　greatly　enhanced　than　that　of　pristine　BiOCl-OV　(4.1　μmol　h−1).　The　density　functional　theory　(DFT)　calculation　suggests　that　because　of　the　introduced　Br　atoms　and　the　oxygen　vacancies,　the　adsorbed　N2　on　Br-BiOCl-OV　exhibits　greater　N[sbnd]N　bond　length　than　that　adsorbed　on　pristine　BiOCl-OV,　attributing　to　the　effective　activation　of　the　inert　N[sbnd]N　bonds.　Photocurrent　response,　state/transient　PL　spectra　and　electrochemical　impedance　spectroscopy　indicate　that　the　Br-BiOCl-OV　possesses　promoted　charge　separation　and　suppressed　charge　recombination,　which　finally　leads　to　the　high　N2　photo-fixation　performances.　©　2019　Elsevier　Inc.