The electric double layers at oxide aqueous interfaces are responsible for an enormous variety of interfacial phenomena. Yet because of our limited means to access and control the double layers, many possible functionalities have been beyond our reach, and much remains unclear at the molecular level. Here we show that electrical gating can be an effective tuning knob of double layer properties independent from the usual means of adjusting bulk electrolyte composition. Combined with the sum-frequency vibrational spectroscopy, the scheme allows us to directly probe the microscopic structure of the bonded interfacial layer at a charged oxide/water interface. Using the gated silica/water as a model system, we extracted information about how the vicinal water bonding structure varies with surface charge density. More generally, the scheme may open up opportunities to study such interfaces over a range that cannot be reached before.

Bonding structure of electrically gated oxide/water interfaces

2019 Fall National Meeting

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