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Title: Stabilization of Hydroxide Ions at the Interface of a Hydrophobic Monolayer on Water via Reduced Proton Transfer

Journal Article · · Physical Review Letters

We report a joint study using surface-specific sum-frequency vibrational spectroscopy and ab initio molecular dynamics simulations, respectively, on a pristine hydrophobic (sub)monolayer hexane-water interface, namely, the hexane/water interface with varied vapor pressures of hexane and different pHs in water. We show clear evidence that hexane on water revises the interfacial water structure in a way that stabilizes the hypercoordinated solvation structure and slows down the migration of hydroxide ion (OH) relative to that in bulk water. Furthermore, this mechanism effectively attracts the OH to the water-hydrophobic interface with respect to its counterion. The result illustrates the striking difference of proton transfer of hydrated OH at the interface and in the bulk, which is responsible for the intrinsic charging effect at the hydrophobic interface.

Research Organization:
Princeton Univ., NJ (United States); Univ. of California, Oakland, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC); National Natural Science Foundation of China (NSFC)
Grant/Contract Number:
SC0019394; AC02-05CH11231; 11874123
OSTI ID:
1853199
Journal Information:
Physical Review Letters, Vol. 125, Issue 15; ISSN 0031-9007
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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