Effect of Co-doping on the performance of nanosheet-like ZnO ethanol gas sensor

In this paper, a hydrothermal method was applied to synthesize the nanosheet-like pure ZnO and 0.5%, 1 and 3% Co-doped ZnO (Co-ZnO). The pristine and Co-doped ZnO flower-like particles were assembled by porous nanosheets, with the uniform diameter about 18 μm. The N2-BET test found that Co doping significantly increased the specific surface area of the material which was conducive to gas diffusion and adsorption. HRTEM presented that 1% Co-ZnO nanosheets were composed of coral-like nanoparticles. The lattice distances 0.259 nm and 0.276 nm correspond to (002) and (100) crystal plane of ZnO. The gas sensing properties reveal that the 1% Co-doped ZnO present an outstanding enhanced sensitive performance comparing with pure ZnO to ethanol. To 100 ppm target gas, the response increased from 103 to 279.8 and the optimal operating temperature decreased from 369 to 348 °C, and the recovery time decreased from 40 to 18 s. The increased surface carrier concentration which promoted oxygen adsorption by Co was considered to be the key factor to improve the performance.