Design of highly sensitive and selective xylene gas sensor based on Ni-doped MoO3 nano-pompon

MoO3 gas-sensing materials with different Ni2+ doping concentration were prepared by a simple one-step sol-vothermal method. The phase structure, micro-structure and morphology of the as-prepared samples were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM) and the transmission electron microscope (TEM) etc., respectively. The morphology can be changed by adjusting the doping concentration of Ni2+. Among them, the 5 mol% Ni-doped MoO3 sample with a pompon-like morphology improved gas accessibility significantly. Prominently, the response of the sensors on xylene was increased 18 times from 3.48 to 62.6, the response time was about 1 s and the best selectivity was obtained at the optimum temperature of 250 degrees C. These breakthroughs are attributed to the increase of surface-active sites and the improvement of micro-morphology caused by Ni2+ doping.