“…Although Co 3 O 4 nanostructures with various morphologies have been synthesized [23][24][25][26][27], very little work has been directed towards fabricating gas sensors based on these nanostructures, and there are no reports on the gas-sensing properties of Co 3 O 4 hollow nanospheres. It is well known that the surfactant-assisted solvothermal route is very effective to synthesize various nanostructured materials [28][29][30]. Herein, we report the solvothermal synthesis of p-type Co 3 O 4 hollow spheres and their gas-sensing properties towards the vapors of a variety of typical organic solvents and fuels, including acetone, ethanol, toluene, butanol, propanol, and gasoline.…”