Edge-enriched CeO₂/MoS₂ heterostructure with coupled interface for enabling selective room-temperature NO₂ detection

Endowed with abundant oxygen vacancy and excellent redox properties, CeO₂ has attracted extensive attention for potential application in gas sensing, while it suffers from high working temperature and low sensing response. Herein, the MoS₂ nanoflowers with abundant edges are coupled with CeO₂ nanoparticles and the edge-enriched heterostructure is formed at interface. Owing to the synergistic effects of strong adsorption, abundant adsorption sites, and coupled interface, the CeO₂/MoS₂ compounds behave excellent room-temperature NO₂ sensing performance. The 5 ppm NO₂-sensing response of compounds is enhanced by 1033 % and 450 % in company with pure CeO₂ and MoS₂, respectively and the low detection limit of 1 ppm, high recovery rate, excellent long-term stability and selectivity are also obtained at room temperature. According to first-principles calculation, the binding energy of CeO₂ for NO₂ is much more negative than that of MoS₂. Functionalization of MoS₂ with CeO₂ substantially improves NO₂ adsorption. The Fermi level of MoS₂ is nearer to the vacuum level than that of CeO₂. The electrons are transferred from MoS₂ to CeO₂ at interface to create an electric field and an electron accumulation layer is formed on CeO₂ to promote electron exchange between NO₂ and the sensor and the NO₂-sensing response. The results promote the application of two-dimensional materials to gas sensing boding well for the wireless sensing systems development in environmental and safety monitoring.