(001)-Exposed mesoporous SnO2 nanosheets for room temperature trace chlorine monitoring.

SnO2 mesoporous nanosheets with dominant the (001) crystal planes were synthesized via a mesoporous template-confined strategy. The cetyltrimethylammonium chloride used was both the mesoporous template and structure-directing agent, which enables the SnO2 nanosheets to have a rich mesoporous structure and effectively promote the rapid diffusion of gaseous chlorine (Cl2). Meanwhile, the abundant Sn unsaturated coordination sites on the (001) planes significantly enhance Cl2 adsorption. The SnO2-(001) sensor achieved highly sensitive detection of Cl2 at room temperature. It exhibited a high response of 408 toward 5 ppm Cl2, low practical detection limit (10 ppb), excellent selectivity and long-term stability. This breakthrough not only overcomes the high-temperature working limitation of traditional SnO2-based Cl2 sensors. In addition, the sensor was employed to monitor Cl2 emissions during the use of chlorine-containing disinfectants. Test results indicated that the Cl2 concentration surpassed the safety threshold within 7-14 min of disinfectant application. It demonstrated its strong potential for practical applications. Furthermore, it lays the solid foundation for optimizing other metal oxide-based room temperature gas sensors.