Synergically engineering defect and interlayer in SnS2 for enhanced room-temperature NO2 sensing

Defect and interlayer engineering are considered as two promising strategies to alter the electronic structures of sensing materials for improved gas sensing properties. Herein, ethylene glycol intercalated Al-doped SnS2 (EG-Al-SnS2) featuring Al doping, sulfur (S) vacancies, and an expanded interlayer spacing was prepared and developed as an active NO2 sensing material. Compared to the pristine SnS2 with failure in detecting NO2 at room temperature, the developed EG-Al-SnS2 exhibited a better conductivity, which was beneficial for realizing the room-temperature NO2 sensing. As a result, a high sensing response of 410% toward 2 ppm NO2 was achieved at room temperature by using the 3% EG-Al-SnS2 as the sensing material. Such outstanding sensing performance was attributed to the enhanced electronic interaction of NO2 on the surface of SnS2 induced by the synergistic effect of Al doping, S vacancies, and the expanded interlayer spacing, which is directly revealed by the in-suit measurement based on near-ambient pressure X-ray photoelectronic spectroscopy (NAP-XPS). Furthermore, to identify the role of Al doping, S vacancies, and the expanded interlayer spacing in enhancing the NO2 sensing properties, a series of comparative experiments and theoretical calculations were performed.