Au/ZnO hollow spheres with different mass ratios were synthesized by a simple two-step method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) were used to characterize the as-prepared Au/ZnO hollow spheres. The photocatalytic activity of the Au/ZnO composites was evaluated by the degradation of rhodamine B (RhB) dye under white light. Compared with pure ZnO hollow spheres, the degradation rate of RhB was enhanced by 73%with the appropriate amount of Au in the modified ZnO photocatalysts. The influence of Au decoration on the surface photo-induced charge-transfer behaviour of ZnO was investigated by surface photovoltage spectroscopy (SPS) and transient photovoltage (TPV). The results showed that the improved photodegradation by Au/ZnO hollow spheres was mostly caused by the strong electronic interactions between ZnO and the Au nanoparticles. The appropriate load of Au nanoparticles in ZnO promoted the separation of photogenerated charges, thus extending the transmission time of the charge carrier and increasing the lifetime of the photogenerated charges, resulting in highly efficient photocatalysis.
Received: 20 January 2016
Published: 22 April 2016
Fig 6 UV-Vis DRS spectra of the as-prepared ZnO and Au/ZnO hollow sphere photocatalysts
Fig 7 SPS of the as-prepared ZnO and Au/ZnO hollow sphere photocatalysts
Fig 8 TPV spectra of the as-prepared ZnO and Au/ZnO hollow sphere photocatalysts under ultraviolet light The samples excited with a laser radiation pulse with a power of 50μJ, wavelength of 355 nm and pulse width of 5 ns.
Fig 9 Kinetics curves of photodegradation of RhB using the as-prepared ZnO and Au/ZnO hollow spheres under white light (UV + visible light)
Fig 10 Kinetics curves of photodegradation of RhB using 1.5% (w) Au/ZnO hollow spheres under white light and visible light (λ > 420 nm)
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