Quantum dot of copper (Cu) and nanoparticles of copper and copper oxide (Cu2O, 6CuOCu2O, Cu3O4) were synthesized by electrochemical route using the tri-sodium citrate (TSC) and ascorbic acid as a capping and reducing agent. The synthesis was done at 3.2 V, 311 K and 15 V, 373 K using copper rod as a working electrode and platinum wire as a reference electrode. The electrochemical set up was kept under inert nitrogen-purged conditions. Cu nanoparticles were synthesized in large-scale for the first time by direct dissolution of Cu 2+ into the solution of capping agent from copper electrode in the electrochemical cell. Nanoparticles were characterized by using UV–visible absorption spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques. High resolution TEM pictures showed the formation of different shapes of nanostructures such as spherical, dendrites and leaf-shape respectively. The copper nanoparticles in presence of 200 mM of ascorbic acid were obtained with sizes of 2.10 - 4.81 nm in spherical shape and 24.5 - 49.4 nm with 2.88 mM of ascorbic acid. At lower concentration, the particles were also obtained in leaf-shape with ascorbic acid. The leaf shape was also obtained with 250 mM of TSC. This new kind of synthesis method shows the excellent stability compared with that of another chemical method of copper nanoparticles. These particles were used for degradation of methyl orange. The kinetic study of methyl orange with leaf shape particle capping via TSC shows complete degradation of methyl orange in 120 min.