Biogenic Synthesis of High-Performance α-MoO3 Nanoparticles from Tryptophan Derivatives for Antimicrobial Agents and Electrode Materials of Supercapacitors

Abstract

Molybdenum trioxide nanoparticles (MoO3 NPs) are recognized for their applications in novel multifunctional devices. Here, a biogenic, environmentally friendly method using Lepidagathis cristata leaf extract was employed to synthesize MoO3 NPs. The as-obtained MoO3 NPs exhibited a predominant (0 k0) orientation, representing an α-MoO3 structure. The absorption band at 984 cm-1 observed in the Fourier-transform infrared spectrum corresponded to the terminal Mo = O bond, thereby confirming that the prepared MoO3 NPs were in the orthorhombic phase. Scanning and transmission electron microscopy data revealed that the MoO3 NPs were well crystallized and uniformly distributed with grain sizes in the 70-100 nm range. The biogenic MoO3 NPs demonstrated an excellent zone of inhibition against the selected Gram -ve and Gram +ve bacterial strains, thus providing an alternative to standard antibacterial agents. During electrochemical experiments conducted in a 1 M aqueous Na2SO4 solution, cyclic voltammetry (CV) curves of the MoO3 NPs showed a pseudocapacitive nature, with a high discharge specific capacitance of 294 F/g and good cyclability. These results suggest the feasibility of the proposed biogenic, environmentally friendly method for preparing MoO3 NPs for application in multifunctional devices.