Abstract: The interaction among units favors the separation of the photogenerated electron /hole pairs, which is an effect method to improve its photocatalytic performance .Layered double hydroxides ( LDHs) sheets grew vertically on the surface of Fe 3 O4 introducing Cu , which exhibited good visible-light photocalytic property .The morphology , particle size , crystallinity , magnetic property and compositions were characterized by X-ray diffraction, scanning electron microscopic analysis , X-ray photoelectron spectroscopy , infrared spectrum and alternating gradient magnetometer .The photocalytic property of the single materials, the mixture of Fe3 O4 and Cu-Mg-Al-LDHs powders, and Fe3 O4/Cu-Mg-Al-LDHs were investigated.The experimental results show that Fe 3 O4/Cu-Mg-Al-LDHs composites exhibited better visible-light photocalytic property in the degradation of methyl orange .In addition , Fe3 O4/Cu-Mg-Al-LDHs composites can be separated by applying an appropriate magnetic field .

Key words: The interaction among units favors the separation of the photogenerated electron /hole pairs, which is an effect method to improve its photocatalytic performance .Layered double hydroxides ( LDHs) sheets grew vertically on the surface of Fe 3 O4 introducing Cu , which exhibited good visible-light photocalytic property .The morphology , particle size , crystallinity , magnetic property and compositions were characterized by X-ray diffraction, scanning electron microscopic analysis , X-ray photoelectron spectroscopy , infrared spectrum and alternating gradient magnetometer .The photocalytic property of the single materials, the mixture of Fe3 O4 and Cu-Mg-Al-LDHs powders, and Fe3 O4/Cu-Mg-Al-LDHs were investigated.The experimental results show that Fe 3 O4/Cu-Mg-Al-LDHs composites exhibited better visible-light photocalytic property in the degradation of methyl orange .In addition , Fe3 O4/Cu-Mg-Al-LDHs composites can be separated by applying an appropriate magnetic field .