Coupling　two-dimention　carbon　materials　like　graphene　on　photodelectrode　can　achieve　high-efficiency　photoelectrochemical　cells.　Bottom-up　synthesis　of　carbon-based　two-dimensional　materials　in　green　media　from　simple　molecules　is　very　attractive　but　remains　a　challenge.　Carbohydrate　is　an　ideal　precursor　for　the　synthesis　but　previous　report　requires　pyrolysis　at　high　temperature　(＞　700　°C).　Herein,　starting　with　glucose,　we　develop　a　low　temperature　(210　°C)　synthesis　of　carbonaceous　nanosheets　in　aqueous　solution　of　glucose.　With　the　aid　of　ethylenediamine　and　Fe3+/Fe2+/Co2+/Ni2+　ions,　the　nanosheets　can　grow　on　hematite　nanorod　array　with　very　close　contact.　Importantly,　a　metallic　region　is　formed　at　the　interface　due　to　atom　distribution　distortion,　which　can　promote　the　charge　transfer.　The　activity　can　be　greatly　enhanced　by　about　500%　due　to　fast　charge　transfer.　This　is　much　better　than　that　prepared　by　physically　or　chemically　mixing　graphene　and　hematite　(　©　2021,　Tsinghua　University　Press　and　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.