The synergistic effects of oxygen vacancy engineering and surface gold decoration on commercial SnO2 for ppb-level DMMP sensing

The metal oxides-based chemiresitive gas sensors have attracted enormous interest because of their exellent sensing perforamcnes, which have emerged as very promising candidates for gas monitoring. However, from the view of organophosphorus compounds detection, a unique combination of low detection limit and fast respons/recovery rate remainschallenging. Herein, the synersgitic effects of oxygen vacancy engineering and surface gold decoration enabling excellent sensing performances for detection of dimethyl methyl phosphonate (DMMP, a typical organophosphorus) is reported. To demonstrate the proof of concept, Au nanoparticles (NPs) decorated oxygen vacancy-enriched SnO2 hybrids (designated as Au-O-SnO2) were designedas sensing materials, where the O-SnO2 samples were fabricated by introduction of oxygen vacancies onto commercial SnO2 through organometallic chemistry-assisted approach using (CH3)2SnCl2 as precursor, followed by deposition of Au NPs by an in-situ reduction routine. After optimizing Au NPs content in hybrids (1 wt%, 3 wt%, 5 wt% and 7 wt%), O-SnO2 decorated with 5 wt% Au NPs (designated as Au-O-SnO2-5) exhibits excellent DMMP sensing performances, such as, an enhanced recoverable response of 1.67 to 680 ppb DMMP, low detection limit of 4.8 ppb, shortresponse time of 26 s and recoverytime of 32 s, as well as good selectivity, which are much better than that of commercial SnO2 (C-SnO2) and O-SnO2, and Au NPs decorated C-SnO2. Based on the detailed investigation, the enhanced DMMP sensing performances of Au-O-SnO2 hybrids can be mainly ascribed to the synergistic effect of increasing surface active sites induced by oxygen vacancies, the chemical and electronic sensitization of Au NPs. As a result, Au-O-SnO2-5 hybrids display relatively low activation energy of 24.11 kJ/mol for DMMP oxidization, which is lower than that of O-SnO2 (35.54 kJ/mol). Our results provide a feasible method for boosting sensing performances for DMMP detection, paving new way for fabrication of metal oxides-based gas sensors for rapid detection of trace organic compounds with complexed structures.