Redox-driven synthesis of stable copper nanoparticles via metal displacement and their application in organic dye degradation

Abstract

This study uses a novel approach to synthesize copper nanoparticles (Cu NPs) using tartaric acid as a reducing and capping agent via a metal displacement method. The uniqueness of this approach lies in its clean and efficient synthesis route that enables the formation of metallic copper nanoparticles under mild conditions by employing tartaric acid as a dual-functioning complexing and capping agent, and utilizing a spontaneous metal displacement reaction with aluminum. The quality of the synthesized Cu NPs is clearly reflected in the characterization results, which show an average size of 3 nm, sharp crystallinity (crystallite size around 32 nm), the absence of oxide phases, and strong surface functionalization, confirming the successful formation of stable, oxidation-resistant metallic copper. This approach stands out for producing structurally pure and chemically intact Cu⁰ nanoparticles without relying on toxic chemicals or inert environments. Evaluation of the photocatalytic activity of the Cu NPs by monitoring the degradation of sample pollutants under visible light irradiation revealed their exceptional efficiency in the removal of organic contaminants from wastewater. The localized surface plasmon resonance (LSPR) effect is a unique property of copper nanoparticles that enables them to absorb visible light, further making them an auspicious material for photocatalytic applications. The synthesized Cu nanoparticle photocatalyst exhibited excellent visible-light-driven degradation efficiencies of 97.9% for rose bengal (k = 0.043 min⁻¹) and 88.0% for methylene blue (k = 0.026 min⁻¹). These results highlight its strong photocatalytic performance and favorable reaction kinetics. This synthesis strategy offers a sustainable route to producing high-quality copper nanomaterials with promising applications in environmental remediation and advanced photocatalytic systems.