First-principles simulations of vibrational spectra of electrified Si/water interfaces*

Probing electrified interfaces is critical to understanding many phenomena relevant to transient electronics, photoelectrochemical modulation of biological cells and tissues, and photoelectrocatalysis. However, it remains challenging to devise atomistic models of electrified interfaces that can be used to predict electrochemical processes at the microscopic scale. We investigated an electrified hydrogenated silicon/water interface using first-principles molecular dynamics simulations (FPMD) and the Qbox code (http://qboxcode.org/), and we predicted capacitive and Faradaic currents, consistent with experimental results [1]. We then used FPMD to study the vibrational properties of the interface, including Raman spectra. Our analysis in terms of effective polarizabilities reveals differences in hydrogen bonding between the pristine and electrified interface, as well as differences in molecular orientation. Work is in progress to compare simulation results with experiments.

[1] Z. Ye, A. Prominski, B. Tian, and G. Galli, Proceedings of the National Academy of Sciences 118, (2021).