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 I2 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 O2 catalysed whilst, uneven surface, fewer dense packing particles and macropore structures were observed for ZnO prepared without excess of O2. It was shown that diffusion of O2 has improved the structural and photoluminescence behaviour of the prepared ZnO nanoparticles. ZnO synthesised with O2-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 O2 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 O2 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 O2, ZnO calcined without excess of O2 at 850 °C displays violet and green emission with energy at 2.93 eV and 2.35 eV, respectively.