Metal　organic　frameworks　(MOFs)　have　emerged　as　a　new　class　of　multifunctional　porous　materials,　and　more　particularly　the　family　of　zeolitic　imidazolate　frameworks　(ZIFs)　have　shown　great　promise　in　the　applications　of　carbon　dioxide　capture　and　storage.　The　CO2　photoreduction　system　was　established　by　employing　CdS　semiconductor　and　Co-ZIF-9　to　act　as　a　catalyst　and　a　cocatalyst,　respectively.　This　hybrid　system　cooperating　with　bipyridine　and　triethanolamine　exhibits　high　catalytic　activity　in　the　deoxygenative　conversion　of　CO2　to　CO　under　visible　light　irradiation　at　mild　reaction　conditions.　13CO2　isotopic　experiment　validated　that　the　produced　CO　was　from　the　photoreduction　of　CO2,　instead　of　organics　in　the　system.　The　effect　of　parameters　such　as　cocatalyst　concentration,　reaction　temperature,　solvent　properties,　and　water　effect　were　investigated　in　details.　Under　the　optimized　reaction　conditions,　a　high　apparent　quantum　yield　of　1.93%　was　achieved　under　monochromatic　irradiation　of　420nm.　The　uniqueness　of　Co-ZIF-9　in　supporting　CdS　for　CO2　reduction　reaction　was　explored　by　comparing　its　catalytic　functions　with　other　MOFs.　In-situ　photoluminescence　and　photocurrent　generation　measurements　demonstrated　the　function　of　Co-ZIF-9　for　promoting　electron　transfers.　At　last,　a　possible　reaction　mechanism　of　the　photoreduction　reaction　was　proposed.　©　2014　Elsevier　B.V.