PNNL

Abstract

Noble gases, notably xenon plays a pivotal role in diverse high-tech applications ranging from lighting, laser technology, space exploration to medical devices. The escalating demand for xenon necessitates an annually increasing production rate. However, manufacturing xenon is an inherently challenging task, not only due to its unique physical and chemical properties but also because of its trace abundance in the Earth's atmosphere. Consequently, there is a pressing need for the development of efficient methods for the separation of noble gases. Using mild fluographene chemistry we synthesized nitrogen-doped graphene (GN) materials with abundant aromatic regions and extensive nitrogen super doping within the vacancies and holes of the aromatic lattice. Due to organized interlayer 'nanochannels', nitrogen functional groups, and defects within the 2D structures, GNs exhibited effective storage for Kr and demonstrated superior selectivity for Xe/Kr performance at low pressure. The enhanced selectivity is attributed to stronger binding affinity of Xe over Kr to GN governed by London dispersion forces, as evidenced by theoretical calculations utilizing also symmetry-adapted perturbation theory (SAPT) analysis. Investigation of other nitrogen-doped graphene derivatives differing in nitrogen content, surface area, and pore sizes, underscores the significance of nitrogen functional groups, defects, and interlayer nanochannels over surface area in achieving the super selectivity. This work offers a new perspective on the design and fabrication of functionalized graphene derivatives, exhibiting superior noble gas storage and separation activity exploitable in gas production technologies.