Microwave hydrothermal synthesis of K+ doped ZnO nanoparticles with enhanced photocatalytic properties under visible-light

• K+ doped ZnO photocatalyst prepared by microwave hydrothermal method.
• K+ doping changes the ZnO crystallites morphology.
• K+ doping may form defect to improve the photocatalytic activity of ZnO crystallites.

Potassium doped ZnO crystallites were successfully synthesized via a microwave hydrothermal method with Zn(NO3)2·6H2O and KNO3 used as source materials. The phase and microstructure of the as-prepared Zn1−xKxO crystallites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ultraviolet–visible (UV–vis) spectrum and photochemical reaction instrument were used to analyze the photocatalytic properties of the particles. Results show that the diffraction peaks of the K+ doped ZnO crystallites shifted slightly toward higher angle when increasing K+ doping concentration was increased from 0% to 0.5%. Moreover, morphology of these ZnO crystallites transforms from lamellar structure to small granules with higher absorption in UV region and narrower band gaps (Eg). Finally, comparing the products to pure ZnO particles exhibits obviously improved photocatalytic properties of the K+ doped ZnO crystallites.

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