Effect and design of Mn 2+ doped ZnO nanostructures for photodegradation and energy storage devices

This paper studies the synthesis of Zn 1-x Mn x O ( x = 0.00, 0.03, 0.06) nanoparticles using the co-precipitation method. The structural, morphological and optical properties were characterized by XRD, FTIR, SEM, HR-TEM and UV–Visible DRS analysis. The structural analysis indicated a hexagonal shape with good crystallinity of the samples. The FTIR absorption peaks confirmed the formation of Zn–O bonding. The surface morphology and particle size were observed by SEM and HR-TEM analysis. The EDS spectra determined the presence of elements Zn, Mn, and O in the samples. The optical band-gap of Mn-doped nanoparticles decreased with increasing concentration from 3.27 eV to 3.09 eV. The photocatalytic activity has been observed with methylene blue (MB) dye under solar irradiation. The Zn 0.94 Mn 0.06 O (Mn = 0.06) nanoparticles photocatalyst has the highest degradation efficiency at 94.08% within 180 min. This result shows that the Mn-doped ZnO enhanced the performance of the photocatalytic activity. In electrochemical performance analysis, undoped and Mn-doped electrodes have been studied 10 mV/s to 100 mV/s scan rate. Mn-doped electrodes decrease the specific capacitance due to low surface area. However, all the undoped and Mn-doped electrodes possess reduction and oxidation peaks, which is considerable for suitable electrode materials for energy storage devices.