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In this work, theoretical calculations were firstly carried out for the rational design of a heterojunction photocatalyst. As predicted, the photogenerated electron of WS2 transfers to the conduction band of β-Bi2O3, while the photogenerated hole of β-Bi2O3 transfers to the valence band of WS2, thus efficiently separating the photogenerated electron–hole pair. Solid structural characterization proved that WS2 nanosheets were well loaded on the surface of β-Bi2O3 hollow spheres. The formation of a heterojunction significantly improves both the intensity and range of visible-light harvesting, along with the charge separation ability of the photogenerated carriers, as confirmed by UV-vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, photocurrent density measurements and electrochemical impedance spectroscopy. Moreover, the photocatalytic degradation of fluoroquinolones (FQs) (ofloxacin (OFL), ciprofloxacin (CIP), and norfloxacin (NOR)) by the obtained photocatalyst was measured under visible-light irradiation. The 8 wt% WS2-coated β-Bi2O3 photocatalyst exhibited superior removal rates for OFL, CIP and NOR, which were 2.32, 2.01 and 1.71 times greater than those of β-Bi2O3 under the same conditions, respectively. The enhanced photocatalytic performance was attributed to the synergistic effect derived from the p–n junction structure and the core/shell morphology, which enhance the visible-light harvesting capacity, accelerate the separation and transfer of photogenerated charge carriers, and enlarge the specific surface area. The removal efficiency was optimized by modifying a series of parameters including contaminant concentration, photocatalyst dosage, and additive species. In general, this work presents a facile approach for the rational design of p–n core/shell heterojunction photocatalysts, with potential applications in environmental remediation.

The dual defect mediated Z-scheme MoS2/g-C3N4 photocatalyst was fabricated via a simple ultrasonic dispersion and annealing method. The structural, optical and electronic property was systematically characterized. X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the MoS2 was anchored on the g-C3N4 through strong interface electrostatic interaction, which led to the formation of built-in electric field at the contact interface. The optimized MoS2/g-C3N4 heterojunction achieved a superior photoefficiency towards bisphenol A (BPA) degradation and exhibited the reaction rate normalized to specific surface area of 3.22 × 10−4 g·min−1 m−2, approximately 10.0 and 6.7 times larger than these of g-C3N4 and MoS2, respectively. The origin of the enhanced photocatalytic activity of MoS2/g-C3N4 was attributed to the formation of intimate Z-scheme surface heterostructure between MoS2 and g-C3N4, thus improved the light-harvesting ability, facilitated fast charge separation and created more active sites. The impact of anionic towards degradation efficiency was investigated. The degradation activity and degree of BPA were investigated by three-dimensional excitation-emission matrix (3D EEM) fluorescence technique. The Z-scheme charge transfer mechanism and the significant contribution of holes (h+) and superoxide radicals ( O2−) were demonstrated by electron spinning resonance (EPR), radical scavenger experiment and spectral quantification technology. This work could offer a new protocol for the design of highly efficient heterostructure photocatalysts towards environmental remediation.