Sustainable synthesis of Ag and Cu nanoparticles using Quercus infectoria gall extract: A morphological perspective

This research employed Quercus infectoria gall (QIG) extract as a reducing agent to produce metal nanoparticles (MNPs: Ag and Cu) and unveiled the reaction composition - MNPs morphology relationship. MNPs were synthesized by varying the volume ratio of metal ion solutions to QIG extract (1:1, 2:1, 4:1, and 8:1). Maximum absorption at specific wavelengths (Ag: 406–415 nm, and Cu: 320–325 nm) indicated the optimum formation of the AgNPs 8:1, and CuNPs 2:1. AgNPs were elongated and ellipsoid-shaped, while CuNPs were elongated block-shaped. The average size of AgNPs and CuNPs was 108 nm and 197.6 nm, respectively. The difference in the morphology and particle size of MNPs could be correlated with the reducibility of the metal ions and the presence of reducing groups (-OH) in the QIG extract. Metal ions with higher reduction potentials (Ag) tend to form more spherical MNPs due to the rapid reduction and nucleation of the MNPs. The ions with lower reduction potential (Cu) require a longer reduction time. This provides sufficient time for crystal growth, resulting in elongated particle morphology. This work provides a facile and sustainable strategy for designing MNPs with different morphologies.