The effects of oxygen-catalysed and heat treatment on the precipitation synthesised ZnO nanoparticles

Abstract

Nanocrystalline ZnO particles prepared by precipitation method from Zn and I 2 reaction with oxygen as catalyst were investigated. The addition of diethanolamine (DEA) as capping agent and fast pyrolysis treatment at 550, 700 and 850 C were also characterised and elaborated. Compact and small spherical particles were observed for ZnO synthesised with O 2 catalysed whilst, uneven surface, fewer dense packing particles and macropore structures were observed for ZnO prepared without excess of O 2 . It was shown that diffusion of O 2 has improved the structural and photoluminescence behaviour of the prepared ZnO nanoparticles. ZnO synthesised with O 2 -catalysed exhibited better crystalline and leaned towards a pure state as shown by shifting of PL peak to higher energy of pure ZnO while, sample prepared without excess of O 2 exhibits poor crystalline and decreasing of the energy band gap with respect to increment of calcination temperatures. Single violet emission was observed in all samples synthesised with excess of O 2 whereby the highest intensity was obtained by calcining at 850 C with photon energy at 2.95 eV. In contrast to sample with excess of O 2 , ZnO calcined without excess of O 2 at 850 C displays violet and green emission with energy at 2.93 eV and 2.35 eV, respectively.