Dynamic nanoscale imaging of enriched CO adlayer on Pt(111) confined under h-BN monolayer in ambient pressure atmospheres

Fundamental understanding of chemistry confined to nanospace remains a challenge since molecules encapsulated in confined microenvironments are difficult to be characterized. Here, we show that CO adsorption on Pt(111) confined under monolayer hexagonal boron nitride (h-BN) can be dynamically imaged using near ambient pressure scanning tunneling microscope (NAP-STM) and thanks to tunneling transparency of the top h-BN layer. The observed CO superstructures on Pt(111) in different CO atmospheres allow to derive surface coverages of CO adlayers, which are higher in the confined nanospace between h-BN and Pt(111) than those on the open Pt surface under the same conditions. Dynamic NAP-STM imaging data together with theoretical calculations confirm confinement-induced molecule enrichment effect within the 2D nanospace, which reveals new chemistry aroused by the confined nanoreactor.