Limited volume heating method: a simple low cost approach to synthesize additive free long nanowires.

A new type of limited volume heating system (LVH) is designed for the enhancement of the efficiency of conventional hydrothermal method to obtain additive free long nanowires (NWs). In LVH system, the period of chemical reaction is enhanced due to the supply of fresh chemicals by the convection of precursors between different temperature zones. In this work, the performance of the LVH system is investigated by synthesizing an array of long zinc oxide (ZnO) NWs as a case study. Morphological characterizations revealed the formation of long NWs of different dimension with growth temperatures, precursor concentrations and growth durations. The length of the NWs is greatly influenced by the variation in growth time and temperature, whereas their diameter was controlled by changing precursor concentration. The growth of NWs is along (002) direction as revealed by X-ray diffraction and transmission electron microscopy studies. In this technique, the length of the NWs is increased upto five times in comparison to those grown by conventional global heating (CGH) method and thereby proving an enhanced performance of LVH system without any additives. Further, photoresponse behavior of the LVH grown long ZnO NWs is evaluated for ultraviolet detection, where photoresponse of 1.7 s and recovery time of 0.8 s is observed. [ABSTRACT FROM AUTHOR]