Electrochemical　reduction　of　CO2　is　still　far　away　from　the　practical　application　because　of　the　stability　of　CO2　and　the　diversity　of　reduction　products.　It　is　thus　of　great　importance　to　further　explore　catalysts　with　high　efficiency　for　CO2　reduction　to　targeting　products.　Herein,　for　the　first　time,　a　hybrid　of　BiO,　decorated　with　carbon　thin　layer　is　developed　as　high　active　electrocatalyst　for　CO2　conversion,　which　is　synthesized　by　pyrolysis　using　Bi　MOF　as　precursor　and　sacrificial　template.　It　is　found　that　the　asprepared　BiO,　catalyst　is　enriched　with　oxygen　vacancies　stabilized　by　the　decorated　carbon　thin　layer.　The　oxygen　vacancies　enriched　BiOx　catalyst　exhibits　superior　performance　for　CO2　reduction　to　formate,　achieving　a　maximum　Faradaic　efficiency　of　89.3%　and　a　maximum　current　density　of　37.8　mA　cm(-2).　The　thin　carbon　layer　and　oxygen　vacancies　improve　the　charge　transfer　of　the　catalyst　and　hence　in　favor　of　the　high　formate　current　density.　The　defects　of　oxygen　vacancies　play　a　vital　role　in　CO2　adsorption　and　activation　and　thereby　further　enhancing　the　electrocatalytic　ability　for　formate　production.　(C)　2020　Elsevier　Ltd.　All　rights　reserved.