Physical and chemical properties of interfacial water affect processes such as heterogeneous catalysis, electrochemistry, atmospheric, environmental chemistry, and biological self-assembly. Our understanding of water as a dielectric medium is based on the linear response theory, which explicitly implies that any response to a weak perturbation, such as electric field near a charged surface, is of the same magnitude and opposite sign for positive vs. negative applied field of a given strength. Vibrational sum frequency generation spectroscopy was used to study interfacial water at graphene electrode, which allows us to continuously tune the applied voltage from positive to negative through the potential of zero charge. The VSFG spectra show pronounced asymmetry with respect to positive vs. negative electrode potential. The results imply that the interfacial water does not follow linear response for the external DC fields of the order of 0.1 V/A.

Asymmetry of the interfacial water response to positive vs. negative electric field

2019 Fall National Meeting

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