Structural, photoluminescent and electrochemical properties of self-assembled Co3[Co(CN)6]2/ZnO nanocomposite

Abstract

Advanced functional nanocomposites designed for multiple applications can be developed using supramolecular chemistry. In this work, we report the synthesis and characterization of nanosized composite material (Co3[Co(CN)6]2/ZnO) formed by cobalt Prussian blue analogue (Co3[Co(CN)6]2) and zinc oxide nanoparticles (ZnO NPs). Structural, morphological and optical characterization, supramolecular arrangement, and electrochemical properties of the materials were investigated. Based on TEM results, Co3[Co(CN)6]2/ZnO predominantly presented a size-polydisperse cube-shaped morphology. A decrease of the nanocomposite mean particle diameter relative to Co3[Co(CN)6]2 was observed. Similar behavior was confirmed by dynamic light scattering with decrease of hydrodynamic diameter value after nanocomposite formation. The Co3[Co(CN)6]2 and Co3[Co(CN)6]2/ZnO exhibited potential zeta values at −69.5 and −59.6 mV respectively suggesting superficial negative character and excellent colloidal stability, even after ZnO NPs incorporation. The electronic spectral of UV–Vis region exhibited semiconductor properties of the nanocomposite despite the presence of the cobalt complex. Interesting that Co3[Co(CN)6]2/ZnO showed a voltammetric profile with two redox pair with E1/2 values of 0.46 and 0.54 V attributed to the Co+/Co2+ and Co2+/Co3+, respectively, and an irreversible reduction process at −0.74 V attributed to Zn2+/Zn0 species, which differ from the electrochemical processes observed for individual componentes, Co3[Co(CN)6]2 (E1/2 = 0.40 V) and ZnO species (Epc = −0.74 V). The electron transport study of the nanocomposite indicated that the both electrochemical redox processes were controlled by diffusion and adsorption.