Rational structure design of sensing materials plays a crucial part in fabricating high performance gas sensors. In this work, three Co₃O₄ samples with different morphologies, including Co₃O₄-C (Cube-shaped Co₃O₄), Co₃O₄-R (Rod-shaped Co₃O₄) and Co₃O₄-S (Sheet-shaped Co₃O₄), were synthesized through a hydrothermal route. Hierarchical structures-dependent gas-sensing properties were further investigated. The toluene sensing performance of Co₃O₄-S hierarchical structure-based sensor outperforms the other two ones. It exhibited higher sensitivity, faster response-recovery speed and better selectivity to toluene at the working temperature of 180 °C. In addition, the Co₃O₄-S-based gas sensor can maintain its sensitivity to toluene after one month, suggesting it good reliability. Preliminary functional tests for the detection of toxic analytes indicated it can be considered as a promising candidate for applications in detecting toluene.

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