Atomic layer deposition of SnO2 on In2O3 enables ultrasensitive NO2 detection at room temperature and DFT mechanism research

The unique electronic and chemical properties of metal oxide heterostructures are critical to the development of room temperature (RT) sensors. In this work, we report the design of In2O3/SnO2 heterostructures based on atomic layer deposition (ALD), which regulates the energy band structure of the material and promotes the electron transfer, thus enhancing the adsorption of target gases. The sensor based on In2O3/SnO2 demonstrates outstanding sensing performance at RT with an extreme response of 2900 to 10 ppm NO2, which to our knowledge outperforms the reported metal oxide sensors, as well as a detection limit of 61 ppb. Density functional theory (DFT) calculations show that the charge transfer (0.494 e) and interaction energy (2.19 eV) between In2O3/SnO2 and NO2 are significantly enhanced. This work highlights the critical function of heterostructured materials in enhancing the sensing capabilities of semiconductors, providing some hints for the design of ultrasensitive NO2 sensors.