Green Synthesis of MnO₂ Nanoparticles with Aqueous Extract of Star Apple Leaves (Chrysophyllum cainito L.)

Abstract

Nanomaterials are materials with a size of ≤100 nm and are important for technology in today’s digital era. MnO2 is one of the most studied metal oxides nowadays because of its abundance, low toxicity, and environmentally friendly. This material can be synthesized via redox reactions. The reagents commonly used in this reaction are typically toxic and environmentally unfriendly, such as H2SO4, HCl and HNO3. Therefore, through this research, the synthesis of MnO2 was carried out using an aqueous extract of star apple leaves. Because the aqueous extract of star apple leaves is known to contain secondary metabolites which have -OH, -C=O, and -C-N groups. These groups act as reducing and capping agents for the synthesis of MnO2 NPs. In addition, this study investigated the effect of the various synthesis methods on the formation of MnO2 NPs. Based on the results of LC-MS characterization, the aqueous extract of star apple leaves contains myricetin. Myricetin has -C=O and -OH groups which are reactive to MnO4- ions in aqueous solution, so that MnO4- is reduced to MnO4. This fact is supported by the results of the P-XRD characterization, which proves the presence of R-MnO2 and γ- MnO2 were obtained.