Experimental investigation on the effect of ligands on copper(I)oxide/copper(II)oxide nanocrystal growth

Abstract

Nano-scale copper oxide play an important role in optoelectronics, photovoltaic, and catalytic applications due to its unique properties. The controlled synthesis of nanoparticles (NPs) has been attributed to the use of capping ligands which binds to NP surface, thus limiting NP size growth and resisting oxidation. In this report, two different experimental methods: polyol reduction and thermal decomposition was employed for the synthesis of Cu/Cu2O/CuO NPs and the surface binding effect of various ligands: oleylamine, oleic acid, trioctylamine, onto the NP surface was investigated using these two methods.

In polyol reduction, mixture of oleylamine and oleic acid in 1:1 ratio was found to enhance oxidation via the proposed cooperative-controlled crystallization mechanism. Additionally, oleic acid has better impedance of particle growth than oleylamine. The size and shape of the NPs were also found to depend on the reaction temperature. In thermal decomposition, it was found that oleic acid used prevents aggregation, whereas on the other hand, oleylamine and a mixture of oleylamine and oleic acid in 1:1 ratio is unable to prevent aggregation of NPs, forming aggregates of shapeless particles.