Ga-Doped ZnO Microbelts Based Resistive-type Sensor for Detection of Acetylene Gas

Structural materials with shorter gas diffusion pathways, lower electrical resistance, and crystal size play a vital role in resistive-type gas sensors. In the present work, ZnO was doped with Ga to lower its electrical resistance and inhibit crystal growth for acetylene sensing. Ga-doped ZnO microbelts were synthesized by electrospinning a solution containing metal precursors and quillaja saponin as a template for the evolution of the belt structure, followed by calcination to achieve microbelts with a BET surface area of 68.5 m2 g-1, an average pore size of 4.6 nm, and ZnO crystals as small as 16.5 nm. The Ga-doped ZnO microbelts exhibited a response (Ra/Rg) of up to 21.0, and a fast response (7.6 s) to 20 ppm acetylene at 400 degrees C in dry conditions. The materials also showed outstanding repeatability of response of 10.04 +/- 0.04 against 10 cycles of 5-ppm acetylene, a response of 2.0 to acetylene as low as 0.2 ppm, and excellent selectivity against 5 ppm of hydrogen, pentane, toluene, carbon monoxide, and methane. The results suggested that Ga doping could effectively improve the electrical conductivity and acetylene sensing performance of ZnO-based sensors.