Hetero-interface Enabled highly responsive acetone Gas sensor based on MOF-derived Co3O4/In2O3 composite

Metal-organic frameworks (MOF)-derived materials have been a research hotspot in the field of gas sensor. In this work, the MOF-derived spindle-like In 2 O 3 mixed with the ZIF-67 was calcined to obtain xCo-In (x = 0.03, 0.05, 0.07) sensing composite materials. Various characterization techniques, such as XRD, SEM, TEM, UV–vis and XPS were adopted to analyze their crystalline structures, detailed morphology structures, texture properties, bandgap width and element valence states. For In 2 O 3 /Co 3 O 4 composites, their sensing properties for acetone are greatly improved compared with pure In 2 O 3 , and the response of 0.05Co-In to 100 ppm acetone can reach 226.1 at an operating temperature of 175 °C with a response time of 1 s In 2 O 3 /Co 3 O 4 composites remained the morphologies of MOF templates, exhibiting large specific surface area. Combining the gas-sensitive behavior with characterization results, the effect of heterojunction between In 2 O 3 and Co 3 O 4 is discussed. Their interface interaction increases the ratio of Co 2+ /Co 3+ , content of oxygen vacancy/adsorbed oxygen, and material resistance, being important reasons for the improved sensing performance. The prominent interface effect may originate from Co 3 O 4 which has the variable valence ion. This work provides a strategy for constructing heterojunction to achieve a high-performance gas sensor.