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.