Biomass-derived porous ZnO hierarchical microtubules for conductometric detection of n-butanol vapor

Abstract

Rapidly conductometric detection of widely used n-butanol vapor has been really desirable owing to its inflammable and explosive hazards. To this end, porous ZnO hierarchical microtubules were simply prepared by a zinc nitrate impregnation and air calcination method using waste rose stem as bio-template, and the effects of different calcination temperatures on the microstructure and gas-sensing performance were also investigated. The ZnO-500 hierarchical structure after calcining at 500 °C is formed by the cross-linkage of small-sized nanoparticles, and has multistage porous distribution and microtubule arrays that facilitate rapid diffusion of n-butanol vapor. The ZnO-500 sensor exhibits short response time (Tres = 2 s), high response (S = 143.0) and low detection limit (10 ppb) to 50 ppm n-butanol vapor at an operating temperature of 252 °C. These gas-sensing indexes are obviously better than those of reported ZnO-based n-butanol sensors. Such excellent gas-sensing performance is mainly derived from the synergism of inherent characteristics of porous ZnO hierarchical microtubules, surface adsorbed oxygen and bio-template imprinting. Therefore, porous ZnO-500 microtubules can be utilized as a candidate sensing material for the detection of trace n-butanol vapor. Moreover, the gas-sensing mechanism is discussed in detail.