Size Refinement of Copper Nanoparticles: A Perspective from Electrochemical Nucleation and Growth Mechanism

In this paper, isotropic copper nanoparticles (CuNPs) were successfully sythesized by using Cu(CH3COO)(2) and ascorbic acid in absolute ethanol solution. With the addition of polyvinylpyrrolidone (PVP) protective additive, the size distribution range of the synthesized CuNPs was significantly reduced from 650 +/- 415 nm to 51 +/- 12 nm. Electrodeposition analysis revealed that PVP could greatly suppress the reduction of Cu but had no prominent effects on the deposition mechanism. Based on the potentiostatic deposition results, a growth model was proposed to improve the applicability of the Scharifker-Hills model by considering both the surface inhibition effect and the mass diffusion during the growth process of Cu nuclei. The experimental data fitted well with the prediction results from the proposed model, indicating that the electrodeposition of Cu followed the progressive nucleation process. The PVP additive could inhibit the deposition and growth of Cu by increasing the surface inhibition for cation incorporation on the nuclei, which was probably the main reason for the refinement of the sythesized CuNPs. Our findings can provide insights for the preparation of metallic nanoparticles and the understanding of their deposition mechanism.