Detection of ppb-Level SO₂ at Room Temperature Based on Bi₂O₂Se Nanosheets

Monitoring sulfur dioxide (SO₂) is crucial for protecting human health as exposure to this pollutant can cause respiratory and cardiovascular illnesses, particularly in vulnerable populations. The primary materials currently used for detecting SO₂ are metal oxides. However, it is still a challenge to detect SO₂ at the parts per billion (ppb) level via these materials even when operated at high temperatures. Herein, we propose a highly sensitive SO₂ sensor that operates at room temperature (RT). The sensing material employed is the hydrothermally synthesized bismuth oxyselenide (Bi₂O₂Se) nanosheets. The Bi₂O₂Se sensor exhibits a response value of 34% to 1 ppm SO₂ and a detection limit of 20 ppb, which surpasses most SO₂ sensors reported to date. The superior sensitivity and selectivity of Bi₂O₂Se nanoppbsheets toward SO₂ are attributed to their strong adsorption energy (-0.76 eV) and significant electron transfer (2.205 e) between Bi₂O₂Se and SO₂ molecules, as confirmed by density functional theory (DFT) calculations. Finally, a wireless SO₂ sensing system is designed and implemented based on the SO₂ sensor, enabling the detection of trace-level SO₂ in indoor environments such as factories and laboratories, thereby protecting the well-being of personal further.