Meso- and macroporous Co₃O₄ nanorods for effective VOC gas sensors

The synthesis of crystalline nanorod metal oxides with porous structure is an important issue in gas sensor technology, which aims to increase their sensitivity and stability. In addition, the development of a facile method to synthesize large yields of nanorods is a key factor in reducing the cost of products in thick film gas sensor technology. Large yields of crystalline meso-/macroporous Co₃O₄ nanorods are fabricated using facile hydrothermal method from CoCl₂ and urea precursors, without using any surfactants or template-directing agents. The gas-sensing properties of synthesized nanorods are tested to volatile organic compounds (VOCs) such as benzene, acetone, and ethanol. Results reveal that crystalline meso- and macroporous Co₃O₄ nanorods have the highest sensitivity to acetone with a fast response and a recovery time of one minute. Moreover, the sensing properties of crystalline meso-/macroporous Co₃O₄ nanorods depend strongly on carrier (reference) gases, whereas preadsorbed oxygen plays an important role in the sensing mechanism of Co₃O ₄-based nanorod sensors for VOCs.