Facile synthesis of Mn₃O₄-ZnO composite for photocatalytic dye removal and capacitive applications

Researchers are focusing on the designing a material's chemistry with novel composition to enhance the efficiency of wastewater treatment and energy storage applications with sufficient stability. Current manuscript presents a detailed comparative study of Mn3O4-ZnO composite for photocatalytic and capacitive applications. The composite samples were prepared through chemical precipitation route to understand the effect of concentration of each component (Mn3O4 and ZnO) on structural and optical characteristics. X-ray diffraction (XRD) and Fourier Transformed Infra-Red spectroscopy (FTIR) confirmed the successful development of both phases with structural modifications in composite sample. Optical absorbance spectroscopy supported the structural amendments with variation in optical band gap (2.71-2.92 eV). Further, the equal concentration (1:1) of Mn3O4 and ZnO exhibited similar to 98 % removal of methylene blue dye under UV-visible lamp (Hg lamp) with highest rate of removal (0.037 min(-1)) among all the prepared samples. Here, the degradation efficiency has been reduced significantly (to 30 %) in alkaline dye solution at pH = 11. Further, the capacitive measurements revealed the highest total capacitance (0.97 F/g) among all the mixed compositions.