Hierarchical　Bi2MoO6　spheres　in　situ　assembled　by　monolayer　nanosheets　were　successfully　prepared　via　a　cetyltrimethylammonium　bromide　(CTAB)-assisted　assembled　strategy　under　different　prepared　conditions.　The　structure,　morphology　and　surface　chemical　state　of　the　prepared　samples　were　well　characterized.　The　AFM　images　(Atomic　force　microscopy)　present　that　the　average　thickness　of　the　nanosheets　for　two　typical　samples　are　about　0.81　and　0.84　nm,　respectively.　The　analysis　results　of　O　1s　XPS　and　in-situ　ESR　indicate　that　there　are　different　concentration　oxygen　vacancies　(OVs)　in　two　prepared　samples　(denoted　as　Vo-rich　and　Vo-poor).　Time-resolved　fluorescence　emission　decay　spectra　show　that　the　carriers　lifetime　of　Vo-rich　and　Vo-poor　are　5.18　and　1.59　ns,　respectively.　Moreover,　in-situ　FTIR　of　benzyl　alcohol　(BA)　absorption　results　suggest　that　rich　oxygen　vacancies　could　facilitate　BA　coordination.　Vo-rich　and　Vo-poor　present　38.2%　and　7.1%　of　conversion　with　high　selectivity　for　benzyl　alcohol　oxidation　under　visible　light　irradiation,　respectively.　The　higher　performance　for　Vo-rich　was　attributed　to　rich　oxygen　vacancies　which　act　as　the　sites　for　the　reactant　activation.　Finally,　a　feasible　reaction　mechanism　was　proposed　to　elucidate　that　enhanced　photocatalytic　activity　over　the　Vo-rich.　©　2018　Elsevier　B.V.