Enhanced visible-light photocatalytic activity of samarium-doped zinc oxide nanostructures

Abstract

In the present work, we have synthesized samarium doped zinc oxide nanostructures (Zn1–xSmxO; x = 0.00, 0.02, 0.04 and 0.06) via chemical precipitation method and studied their structural, morphological, optical and photocatalytic properties. X-ray diffraction (XRD) patterns, PL and Raman spectra results indicate that the undoped and Sm-doped ZnO nanostructures are crystallized in a hexagonal wurtzite structure. FESEM images show that the morphology of the sample changes from cubical to hexagonal nanostructures with increase in Sm3+ doping concentration. The EDX spectra confirm the incorporation of Sm3+ ion in ZnO. The influence of Sm3+ doping on the structure, morphology, absorption, emission and photocatalytic activity of ZnO nanostructures were investigated systematically. The addition of Sm3+ ion leads to a red shift in the optical energy band gap from 3.19 to 2.67 eV and hence, increases the visible light absorption ability. The presence of E2 (H) and E1 (LO) modes in micro-Raman spectra confirms the crystallinity and defects in the samples. The detailed photocatalytic experiments reveal that Sm-doped ZnO nanostructures show the maximum photodegradation efficiency for Methylene blue (MB) dye for x = 0.04, i.e., 94.94%, under visible light irradiation. The photocatalytic efficiency improves by 6.98 times when ZnO is doped with rare earth metal ion (Sm3+) and is a potential candidate for practical applications. The investigation demonstrates that as-synthesized nano-sized photocatalysts act as an efficient photocatalyst for the degradation of MB dye.