Synergistic photocatalytic performance through Z-Scheme charge transfer in organic dye degradation using α-MnO2 nanorods and Co3O4 nanoparticles combined with eggshell derived hydroxyapatite

Abstract

HAp-α-MnO2-Co3O4 nanocomposite was prepared by the wet impregnation technique. Various analytical techniques were used to study the structural, morphology and photophysical characteristics. In the present study, the degradation of MB dye under the visible light irradiation in existence of HAp-α-MnO2-Co3O4 nanocomposite has been examined and the detailed mechanism for the photocatalytic degradation was discussed. The improved photocatalytic degradation activity over the HAp-α-MnO2-Co3O4 nanocomposite can be ascribed to the efficient high generation and low recombination rate of charge carriers under the UV-Visible light. Also, the key features for HAp-α-MnO2-Co3O4 nanocomposite including enhancement of light absorbance, recombination rate of photogenerated charge carriers have also been found for the nanocomposites. Based on photocatalytic degradation, it was found that the HAp-α-MnO2-Co3O4 nanocomposite has the highest photocatalytic activity among all freshly prepared samples. In particular, the MB dye was almost completely degraded (95.5 %) by exposure to UV–visible light in 60 min of irradiation, the observed degradation result was relatively higher than that of pristine HAp, α-MnO2 and Co3O4, respectively. HAp-α-MnO2-Co3O4 nanocomposite efficiently degraded 94.42 % colorless phenol, demonstrating its dual ability to break down hazardous dyes and organic compounds under the same conditions. In addition, the HAp-α-MnO2-Co3O4 nanocomposite has a good recyclability of 90.25 % after five successive cycles. These observed results show that the HAp-α-MnO2-Co3O4 nanocomposite is an environmentally friendly material for environmental remediation.