Effect of type and amount of alumina as dopant over the densification and the electrical properties of zinc oxide ceramic electrodes

Abstract

Aluminum-doped zinc oxide (AZO) electrodes can be a good alternative to replace the expensive electrodes (Ti, ITO, FTO, etc.), which are used in the electrooxidation process to remove refractory and emergent contaminants from industrial wastewaters. AZO electrodes have been prepared by the traditional ceramic method using ZnO as the main raw material and different precursors of Al2O3 as dopant sources. Densification, microstructure and electric resistivity of AZO electrodes are a function of precursor's nature and sintering thermal treatment. The higher the number of precursor's particles and the smaller their size, the sintering temperature needed to attain high densifications and low resistivities shifted to higher values. Micrometric and colloidal alumina were the precursors which allowed to equilibrate an affordable sintering temperature interval (1200–1300°C) with acceptable densification and resistivity values (around 95% and 5×10−3Ωcm, respectively). However, colloidal alumina made it possible to obtain slightly lower values of resistivity at the cost of having a narrower working interval.