Single‐Monolayer Na₂S Film on Metal Surfaces

Na 2 S is a key material in sodium‐sulfur batteries and its single‐monolayer film may also be a new 2D material. Herein, the results are first reported by STM, XPS, and DFT simulation that the Na 2 S single‐monolayer film shows different atomic structures depending on the underlying metals, and these structures can be changed by thermal annealing. All structures are well supported by DFT simulation on corresponding Na 2 S up, down, and standing models, as well as the NaS in‐plane model. Further, a wide bandgap of Na 2 S single‐monolayer film is measured, which decreases from Au(111) to Ag(111) and Cu(111) due to the different Na 2 S interactions with metal substrates. Finally, it is demonstrated that dibenzo 18‐crown‐6‐ether molecules can grow on phase VI of Na 2 S film at room temperature, as compared with preferred metal surfaces and Na 2 S phase III structure.