Green Synthesis of Bimetallic Cu-Ag Nanoparticles Using Aqueous Leaf Extract of Azadirachta indica and Catalytic Reduction of 4-Nitrophenol

International Journal of Chemistry | Vol. 5, No. 8, August 2014 | pp. 57–64

DOI: 10.46882/2014/IJC/000071

Article Type: Original Research Paper

Title: Green Synthesis of Bimetallic Cu-Ag Nanoparticles Using Aqueous Leaf Extract of Azadirachta indica and Catalytic Reduction of 4-Nitrophenol

Names of Authors: S. I. Musa¹, T. A. Al-Shehri²*

Authors’ Affiliations:
¹Department of Chemistry, University of Jos, Jos, Nigeria.
²Department of Chemistry, King Abdulaziz University, Jeddah, Saudi Arabia.

Abstract: The fabrication of bimetallic nanoparticles using plant extracts represents an active frontier in sustainable heterogeneous catalysis due to synergistic electronic interactions at the nano-interface. This study details the green synthesis of stable copper-silver (Cu-Ag) core-shell nanoparticles utilizing the aqueous leaf extract of Azadirachta indica as a co-reducing and capping agent. The bioreduction process was monitored via UV-Vis spectrophotometry, which revealed a broad surface plasmon resonance peak at 495 nm, indicating alloyed structure formations. Transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) showed spherical particles with an average diameter of 22 nm and uniform copper-silver atomic distributions. X-ray diffraction (XRD) confirmed the highly crystalline nature of the bimetallic system. Fourier-transform infrared (FT-IR) spectroscopy showed that plant polyphenols and flavonoids actively capped the metallic surfaces, preventing structural agglomeration. The catalytic efficiency of the synthesized Cu-Ag nanoparticles was evaluated by tracking the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride (NaBH₄). The bimetallic nanocatalyst accelerated the reaction, achieving 98.6% conversion within 6 minutes, outperforming monometallic equivalents. Kinetic modeling conformed to the pseudo-first-order model with a rate constant of 0.384 min⁻¹, confirming high efficacy for nitro-aromatic wastewater remediation.

Keywords: Bimetallic nanoparticles; Green synthesis; Azadirachta indica; Core-shell structure; Heterogeneous catalysis; 4-Nitrophenol

Manuscript Timeline: Received: January 12, 2014; Revised: February 20, 2014; Accepted: March 15, 2014; Published: August 03, 2014.

Citation: Musa, S. I., & Al-Shehri, T. A. (2014). Green Synthesis of Bimetallic Cu-Ag Nanoparticles Using Aqueous Leaf Extract of Azadirachta indica and Catalytic Reduction of 4-Nitrophenol. International Journal of Chemistry, 5(8), 57–64.

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