Fabrication of Co3O4 nanowires assembled on the surface of hollow carbon spheres for acetone gas sensing

Sensitive analysis of specific volatile organic compounds from exhaled breath from human body can provide useful information for early diagnosis of diseases, and therefore, design and fabrication of sensitive gas sensing materials with low working temperature have attracted extensive attention. In this study, Co3O4 nanowires assembled on the surface of hollow carbon spheres (Co3O4 NWs-HCSs) is successfully realized. Cobalt carbonate hydroxide nanowires assembled on hollow carbon spheres (CoCH NWs-HCSs) were first synthesized by hydrothermal method and the Co3O4 NWs-HCSs were then obtained through the post-annealing treatment (350 degrees C). It was found that without annealing treatment, the prepared CoCH NWs-HCSs are unstable for the acetone sensing at low temperature, with the optimum operation temperature of 200 degrees C and the highest response intensity of 3.71 toward 200 ppm acetone. Differently, the Co3O4 NWs-HCSs are stable for the acetone sensing at low temperature with the optimum operation temperature decreasing to 150 degrees C and the response intensity increases to 23 which is 6 times as high as that of CoCH NWs-HCSs. In addition, the annealed hybrid structure showed high sensitivity to acetone at much lower working temperature of 75 degrees C, indicating the promising application of such Co3O4 NWs-HCSs for low-temperature acetone gas sensors and a step forward to develop new devices.