ZnIn2S4 Nanosheets for Efficient NO2 Detection at Room Temperature: Insights into the Role of Sulfur Vacancies

Engineering atomic vacancies in metal sulfide semiconductors allows for the efficient tuning of their electronic and chemical properties. In this work, we synthesized hollow tubular structures constructed by bimetallic ZnIn₂S₄ using a metal–organic framework (MOF) as the template. We found that the sulfur vacancies in ZnIn₂S₄ enabled extremely fast NO₂ detection with high response at room temperature (RT), and the material with high sulfur vacancy content delivers a 2 times higher response to 10 ppm NO₂ than the device with low sulfur vacancy content. To unveil the crucial role played by sulfur vacancies, DFT calculations were conducted to reveal that sulfur vacancies greatly enhance the interaction and electron transfer between ZnIn₂S₄ and NO₂. This study will provide hints for the engineering of bimetallic sulfide materials for low-power gas sensors at RT.