Enhanced Photocatalytic Removal of Tetrabromobisphenol A by Magnetic CoO@graphene Nanocomposites under Visible-Light Irradiation

A modified, facile, and ultrasonic-assisted approach was developed to synthesize CoO@graphene nanocomposites. The chemical, electronic, and structural characteristics of CoO nanoparticles grown on graphene nanosheets were investigated by scanning transmission X-ray microscopy through spatially resolved X-ray absorption near edge structure spectroscopy and other techniques. Enhanced octahedral Co2+ (Oh) structures of CoO nanoparticles were successfully loaded on the surface of graphene nanosheets, and the photocurrent of CoO@graphene nano-composites was 10.6 times higher than that of CoO nanoparticles. The removal efficiency of recyclable magnetic CoO@graphene nanocomposites reached up to 73.4% for tetrabromobisphenol A (TBBPA) degradation under visible-light irradiation. Free radical trapping experiments revealed that center dot OH radicals were the photogenerated radical species driving the high catalytic activity. Moreover, beta scission and debromination are suggested as two possible pathways of TBBPA degradation under visible light. CoO@graphene nanocomposites maintained high photocatalytic activity after reuse over four cycles, which suggests that the synthesized materials have a promising application for TBBPA removal from wastewater.