High performance MnO2–Al2O3 nanocomposite as white light photocatalyst and bactericidal agent: Insights on photoluminescence and intrinsic mechanism

Abstract

Mn-based photocatalyst and antimicrobial agent was synthesized by ultrasonic-assisted co-precipitation method by keeping MnO2 as active compound and Al2O3 was adopted as catalyst support. XRD and HRTEM analysis verified the co-existence of MnO2 and Al2O3 and the crystalline nature of NCs. The XPS and EDAX revealed the chemical states of elements namely Mn2p, Al2p and O1s. The presence of Mn–O and Al–O–Al bonds were noted through FTIR. The photon absorption ability of NCs in visible region was favoured by the energy bandgap of 2.51 eV. Photoluminescence revealed that the charge carriers in NCs showed an improvement in life time. The NCs exhibited enhanced photocatalytic effect due to its synergetic effect and the photocatalytic performance can be ordered as MnO2/Al2O3 > MnO2 > Al2O3. The enhancement in photocatalysis rate in NCs was attributed by the formation of heterostructure and it prevent the recombination of charge carriers. The OH· radical was the dominant species in dye degradation. The NCs showed high photostability and recyclability, and almost same photocatalytic activity preserved even after sixth recycle. In addition to that, the antimicrobial activity of MnO2/Al2O3 was demonstrated to be efficient in their action against the strains of gram positive and gram negative bacteria than that of the individual MnO2 and Al2O3 NPs. Thus, this multifunctional MnO2/Al2O3 can be used as an efficient candidate for the photocatalytic degradation of toxic dyes and an antimicrobial agent.