Building block-tunable synthesis of self-assembled ZnO quasi-microspheres via a facile liquid process

Abstract

Self-assembled ZnO quasi-microspheres constructed of tunable building blocks have been grown directly through a facile liquid process. The effects of preparation parameters, such as the amounts of triethanolamine (TEA) and types of zinc counterions (SO 4 2−, CH 3COO −), on the morphology of building blocks (BLs) have been examined. Experimental data show that TEA has played a dual key function in the self-assembly process; namely, one is to regulate the morphology of BLs, and the other is to induce the oriented attachment of these particles. A rational formation mechanism is proposed on the basis of detailed results of FESEM, TEM and zeta potentials tests. The overall formation of 3-D self-assembled ZnO quasi-microspheres can be summarized as: (a) growth of ZnO building blocks; (b) preassembly of these BLs into small aggregates; (c) further assembly of these aggregates to form special 3-D architectures. XRD and Raman spectra show that the self-assembled quasi-microspheres have wurtzite structures. Room-temperature PL spectra indicate that they have a potential application as ultraviolet emitters. This work presents a simple route using common organic molecules, TEA, as “growth modifiers”, to the fabrication of novel 3-D self-assembled ZnO superstructures.