Cu2O　is　a　p-type　direct　bandgap　semiconductor　with　a　band　gap　of　2~2.2　eV,　which　has　excellent　visible　light　absorption　and　utilization.　However,　slow　charge　transfer　and　poor　stability　hinder　its　practical　application.　In　this　paper,　a　facile　electrodeposition　approach　successfully　synthesized　the　heterostructure　of　p-Cu2O　and　n-Cu2O.　The　protective　layer　of　n-Cu2O　on　the　surface　of　p-Cu2O　nanoparticles　forms　a　p/n　heterojunction.　Due　to　the　p/n　heterojunction,　the　PEC　performance　of　p/n-Cu2O　is　enhanced　significantly.　The　charge　separation　efficiency　of　photogenerated　electron/hole　pairs　in　p/n-Cu2O　is　greatly　improved.　Therefore,　p/n-Cu2O　shows　superior　photoelectrochemical　(PEC)　CO2　reduction　reaction　(CO2RR)　efficiency　when　used　as　a　photocathode.