: Formaldehyde is a ubiquitous and high toxicity gas. It is an essential task to efficient detect owing to their toxicity and diffusion. In this work, we studied on the detection of trace amount of formaldehyde based on hollow Co₃O₄ nanostructure. It is found that Co₃O₄ hollow spheres with different structures shows distinct sensing performance towards formaldehyde at room temperature, the response value of nanosheet modified

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... > towards 100 ppm formaldehyde will reach 35 in 18 second, and the nanoparticle modified Co₃O₄ hollow sphere will reach 2.1 in 18 second, 17 in 300 second. The nanosheet modified and nanoparticle modified Co₃O₄ hollow sphere will reach 4 and 20 in 10 second towards 100 ppm formaldehyde at room temperature. As room temperature, the sensors do not response towards NH₃, CO, etc. The sensing mechanism was proposed based on the theoretical and experimental results. The Co₃O₄ sensor shows that potential utility in CH₂O quick sensing at room temperature