Sensing mechanisms of gases on solid structures are predominantly surface-dominated. Benign surface features in terms of small grain size, high aspect ratio, large surface area and open and connected porosity, are required to realize a successful sensor material. Such morphological artifacts are a function of the fabrication and processing techniques employed. In this paper, we describe the fabrication of monoshaped and monosized zinc oxide (ZnO) particles by a homogeneous precipitation method, using urea and/or hexmethyltetraamine as the reductant. The effect of operating conditions and experimental variables, such as the relative concentration of the precursors, temperature, and the aging time on the morphology of the resulting particles was studied systematically. These experimental parameters were optimized in order to achieve particles of uniform morphology and of narrow size distribution. Some of these particles were employed for the detection of ammonia gas at room temperature.
Keywords: gas sensor; hexamethyltetraamine; homogeneous precipitation; monodispersion; monosized particles; urea; zinc oxide.