Mn1-xCuxO2/ reduced graphene oxide nanocomposites: Synthesis, characterization, and evaluation of visible light mediated catalytic studies

Abstract

The narrow optical band gap, higher electrical conductivity, and wider-absorption range are three key features that a good photocatalyst must possess. Herein, we have fabricated Cu-doped MnO2 (Mn1-xCuxO2) nanostructure by facile wet chemical approach and formed its nanocomposite with r-GO (Mn1-xCuxO2/r-GO) via ultra-sonication approach. The successful replacement of host metal ions (Mn4+) with the dopant metal ions (Cu2+) was supported with the PXRD, FT-IR, and EDX characterizations. The effect of Cu-doping on the band gap and r-GO matrix on the conductivity of the fabricated nanocomposite was also evaluated via Tauc plots and I–V tests, respectively. The photocatalytic efficiency of the fabricated photocatalysts was tested and compared against the methylene blue (MB) under visible light irradiation. The photocatalytic experiments revealed that Mn1-xCuxO2/r-GO photocatalyst exhibited superior photocatalytic aptitude than that of pristine MnO2 and Mn1-xCuxO2 photocatalysts. More precisely, the Mn1-xCuxO2 photocatalysts degraded 86.89% MB dye at the rate of 0.021 min−1 after a 90-min exposure to the visible light. Observed superior catalytic activity of the nanocomposite can be attributed to the synergistic effects between the Cu doped MnO2 and r-GO nanosheets that resulted in its narrow band-gap (2.19 eV) and excellent conductivity (2.217 × 10−2 Scm−1).