Facile synthesis of monodispersed yolk-shelled molybdenum disulfide microspheres with enhanced photocatalytic properties

The controllable preparation and development of a practical photocatalytic material with yolk-shelled structure remains a great challenge. Herein, monodispersed yolk-shelled molybdenum disulfide microspheres have been synthesized via a facile and economical hydrothermal method with the assistance of a surfactant (polyethylene-polypropylene glycol (P123)). Ostwald ripening is the main formation mechanism for the yolk-shelled structure. The photocatalytic activity of the sample is evaluated by monitoring the photodegradation of rhodamine B (RhB) under white light illumination (500 W xenon lamp) with the assistance of hydrogen peroxide (H₂O₂). The results indicate that the yolk-shelled microspheres display excellent photocatalytic activity and recycling stability. The photocatalytic degradation rate of yolk-shelled MoS₂ microspheres is 97.6% after only 30 min, which is much higher than those of MoS₂ particles synthesized without P123, MoS₂ solid microspheres and commercial MoS₂ (Experimental section) (54.7%, 4.6% and 9.6% at 30 min, respectively). The reaction rate constant (k) of the yolk-shelled microspheres for the photodegradation of RhB is 1.19 × 10^-1 min^-1, which is 1.58, 92.97 and 107.21 times faster than those of MoS₂ particles (k₂ = 7.51 × 10^-2), MoS₂ solid microspheres (k₃ = 1.28 × 10^-3) and commercial MoS₂ (k₄ = 1.11 × 10^-3), respectively. Such a highly desired yolk-shelled structure enables higher multiple light reflections and scattering between the outer spherical shell and the interior core compared with MoS₂ particles, MoS₂ solid microspheres and commercial MoS₂ to provide a more efficient way of enhancing light-harvesting efficiency.