Converting　clean　solar　energy　into　chemical　energy　through　artificial　photosynthesis　is　an　effective　solution　to　solve　the　energy　and　environmental　issues.　Here,　we　report　a　Cs3Bi2Br9/Bi2WO6　(CBB/BWO)　Z-scheme　heterojunction　constructed　via　electrostatic　self-assembly,　which　facilitates　efficient　separation　of　photogenerated　carriers　and　ensures　the　corresponding　redox　capacity　of　both　components.　By　sharing　Bi　atoms,　a　Br-Bi-O　bond　is　established　between　CBB　and　BWO,　serving　as　an　＂electron　bridge＂.　The　electrons　generated　by　BWO　are　efficiently　channeled　to　CBB　through　the　heterojunction-formed　＂electron　bridge＂,　thereby　achieving　effective　photocatalytic　CO2　reduction.　Under　simulated　sunlight　conditions,　it　exhibits　the　highest　CO　yield　of　72.52　mu　mol　g(-1)　(without　the　addition　of　any　precious　metal,　photosensitizers　or　sacrifices),　which　is　approximately　7-fold　and　18-fold　greater　than　that　of　pure　CBB　and　BWO,　respectively.　This　work　provides　a　more　profound　comprehension　of　the　regulation　of　electron　transfer　through　interfacial　chemical　bonds,　thereby　proposing　a　promising　strategy　for　the　development　of　efficient　heterojunction　photocatalysts　for　CO2　photoreduction.