Z-scheme Au@TiO2/Bi2WO6 heterojunction as efficient visible-light photocatalyst for degradation of antibiotics

•Au@TiO2/Bi2WO6 was synthesized by reverse micelle sol–gel method plus hydrothermal process.•Remarkable photocatalytic performance for degradation of antibiotics was achieved.•The Z-scheme charge transfer mechanism for Au@TiO2/Bi2WO6 was verified.•The nanocomposite photocatalyst exhibited superior reusability. Semiconductor photocatalysis can be regarded as one of effective strategies to overcome the great challenges encountered with conventional technologies for environmental remediation. In this research, Z-scheme heterostructure composed of core–shell Au@TiO2 nanoparticles and flower-like Bi2WO6 nanosheets has been successfully prepared through the reverse micelle sol–gel method followed by a hydrothermal process. The structural characteristics, chemical compositions and photoelectrochemical properties of this ternary composite photocatalyst (Au@TiO2/Bi2WO6) were further investigated in detail. Benefitted from the synergy of the heterojunction construction and metallic surface plasmon resonance effect, the Au@TiO2/Bi2WO6 with an optimal mass ratio of Au@TiO2 to Bi2WO6 exhibited the significantly enhanced photocatalytic activity for degradation of antibiotics under visible-light irradiation, in which the degradation efficiency of sulfamethoxazole (SMX) and tetracycline hydrochloride (TC) could be up to 96.9% and 95.0% within 75 min, respectively. The reaction rate constant for SMX and TC degradation was calculated to be around 0.0425 min−1 and 0.0314 min−1, which has 7.2 times and 1.9 times enhancement compared with single Bi2WO6, respectively. In addition, the cyclic stability and photocatalytic mechanism of Au@TiO2/Bi2WO6 were further verified. Our primary results provide a feasible strategy to develop core–shell heterostructured photocatalysts with superior performance for the efficient removal of low-concentration antibiotics in water.