The hydration of halogens has been widely researched because of its close relation with the water desalination and biochemical reactions. In this work, by a combination of scanning tunneling microscopy and X-ray photoelectron spectroscopy, we have explored the hydration process of iodine via the Eley-Rideal process on the Au(111) surface. Moreover, the hydration process of iodine with the presence of the NiPc self-assembled network as a template has also been investigated, where the stepwise hydration of iodine at room temperature can be visualized on Au(111).

Salt dissolution is generally encountered in widespread phenomena in nature. As a typical case, the dissolution of NaCl has been widely investigated in aqueous environment, while the process and mechanism of the on-surface dissolution may differ from that in solution and remain to be explored. Herein, we model a NaCl dissolution process on the Au(111) surface with confined water at room temperature (RT) and above. With the assistance of adenine molecules as water reservoir and carrier, the dissolution of NaCl is achieved above RT via the Langmuir-Hinshelwood mechanism rather than the Eley-Rideal one, along with the selective formation of stable Cl- hydrates, which desorb from the surface in the next step. To explore the generality, such a strategy has been extended to other sodium halide systems ( e. g., NaBr and NaI), and expectedly, the dissolution of sodium halides is also achieved by forming stable Br- and I- hydrates via the Langmuir-Hinshelwood process.