Synthesis and application of nickel compound quantum dots by electrochemical process

Abstract In this work, nickel compound quantum dots (Ni-QDs) are synthesized by the electrochemical process. The electrochemical process known as a facile method is used to prepare Ni-QDs colloid solution. Ni-QDs are synthesized using nickel-metal rods dipped into an electrolyte solution of potassium chloride and citric acid at 0.4M and 0.1M concentrations, respectively, then applied voltages at 1, 3, and 6 V at various synthesis times for the synthesis process. As a result, Ni-QDs are characterized for size by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The absorption spectra of Ni-QDs are indicated via ultraviolet-visible spectroscopy (UV-vis) at 390, 655, and 731 nm of wavelengths, which can be assigned to absorption peaks of Ni (OH)2 and NiCl2, respectively. The crystalline structure and photoluminescence properties of Ni-QDs are examined with selected area electron diffraction (SAED) and photoluminescence spectroscopy. It is found that the Ni-QDs growth rate can be controlled by the various voltages applied in the synthesis process. The smallest size of Ni-QDs is achieved with the low voltage applied (1V) at 6 hrs, while the higher voltage process produced a strong chemical reaction resulting in the lower yield of Ni-QDs due to the large particles of the obtained products. Thus, the Ni-QDs at 1V condition is considered the optimum condition, indicating the smallest hydrodynamic size (187±1.43 nm) and revealing the high stability of Ni-QDs dispersed in solution, as shown in the homogeneous solution compared to Ni- QDs in other conditions. Consequently, the influence of voltage and synthesis time in the synthesis of Ni-QDs is important to optimize the quality of Ni-QDs.