<p>This work presents a hierarchical yolk-shell NiZn-Co₃O₄ sphere with abundant oxygen vacancy by utilizing structure optimization and composition regulation for efficient detection of triethylamine (TEA) gas. A comparative exploration of TEA gas sensing characterization for different Co₃O₄-based sensors is conducted systematically. The result shows that the sensor based on the NiZn–Co₃O₄ HCSS displays the highest sensing response of 42.5 at a working temperature of 180&#xa0;°C. In particular, the NiZn–Co₃O₄ HCSS device possesses a fast response-recovery speed, excellent anti-humidity and outstanding long-term stability of up to 40&#xa0;days to TEA gas. The improved TEA gas sensing property can be attributed to the intriguing hierarchical core–shell architecture and abundant oxygen vacancy induced by NiZn co-doping. Moreover, to study the sensing mechanism in detail, the adsorption behavior and charge transfer phenomenon between O_V–NiZn–Co₃O₄ (110) and TEA molecule is carried out by the density functional theory (DFT). This work demonstrates an outstanding performance of Ni and Zn co-doped hierarchical core–shell Co₃O₄ in TEA detection by combining theoretical and experimental investigations into mechanisms for optimized TEA gas molecule sensing.</p> Graphical abstract <p></p>