MOF-derived Co₃O₄/ZnSnO₃ hollow composite gas sensor with superior response and selectivity toward ethanol

Ethanol is widely used in the chemical and food industries, and its accurate and efficient detection is essential for safety and process control. In this study, ZnSnO₃ hollow microspheres decorated with MOF-derived Co₃O₄ hollow polyhedrons were synthesized via co-precipitation and calcination method. The structure, morphology, surface chemistry, and ethanol-sensing properties of the Co₃O₄/ZnSnO₃ composites were systematically investigated. Compared with pure ZnSnO₃, the composites exhibited significantly increased specific surface area and oxygen vacancy concentration, leading to superior gas-sensing performance. The optimized CZSO-2 composite (15 % Co₃O₄) sensor achieved a high response of 160.6 toward 100 ppm ethanol at 240°C, with rapid response/recovery times of 6/56 s and a low detection limit of 0.21 ppm. Furthermore, the composites demonstrated enhanced selectivity, repeatability, and long-term stability. Mechanistic analysis revealed that the synergistic effects of abundant oxygen vacancies, the large specific area arising from the hollow structure, and the formation of p-n heterojunction between Co₃O₄ and ZnSnO₃ were responsible for the improved performance. Therefore, the MOF-derived Co₃O₄/ZnSnO₃ hollow composites present a promising sensing material for high-performance ethanol detection.