Abstract
In situ electrochemical infrared spectroscopy and Raman spectroscopy are powerful tools for probing potential-dependent adstructures at solid/liquid electrochemical interfaces. However, it is very difficult to quantitatively interpret the observed spectral features including potential-dependent vibrational frequency and spectral intensity, even from model systems such as single-crystal electrode/liquid interfaces. The clear understanding of electrochemical vibrational spectra has remained as a fundamental issue for four decades. Here, we have developed a method to combine computational vibrational spectroscopy tools with interfacial electrochemical models to accurately calculate the infrared and Raman spectra. We found that the solvation model and high precision level in the self-consistent-field convergence are critical elements to realize quantitative spectral predictions. This method's predictive power is verified by analysis of a classic spectroelectrochemical system, saturated CO molecules electro-adsorbed on a Pt(111) electrode. We expect that this method will pave the way to precisely reveal the physicochemical mechanism in some electrochemical processes such as electrocatalytic reactions.
Highlights
The determination of adstructures at electrochemical (EC) solid/liquid interfaces is a fundamental issue in fuel cells, metal/alloy plating and corrosion, etc.[1,2,3] Vibrational spectroscopies can be utilized to provide ngerprint information about adstructures with high spectral resolution and have been developed for the characterization of EC interfacial adstructures by infrared (IR) spectroscopy since the mid-1960s4 and by Raman spectroscopy since the mid-1970s.5 the vibrational frequencies and the intensities of EC-IR and ECRaman spectra strongly depend on the applied potential, electrode materials, coverage of adsorbates and coadsorbed species, and are too complicated to be clearly interpreted in most of cases.[6,7] For instance, with the Stark tuning slope (STS), the slope of the vibrational frequency as a function of the applied potential, it is difficult to precisely quantify potential-dependent behaviours of electroadsorption
One was Pt(111)(2 Â 2)-3CO a1 with one carbon monoxide (CO) molecule adsorbed at an atop site (COL) and two CO molecules at hollow sites (COM) in the unit cell (Fig. 1a)
A theoretical method combining the computational tools of vibrational spectroscopy and interfacial-EC models was developed for quantitatively predicting EC-IR and EC-Raman spectra, 1428 | Chem
Summary
The determination of adstructures at electrochemical (EC) solid/liquid interfaces is a fundamental issue in fuel cells, metal/alloy plating and corrosion, etc.[1,2,3] Vibrational spectroscopies can be utilized to provide ngerprint information about adstructures with high spectral resolution and have been developed for the characterization of EC interfacial adstructures by infrared (IR) spectroscopy since the mid-1960s4 and by Raman spectroscopy since the mid-1970s.5 the vibrational frequencies and the intensities of EC-IR and ECRaman spectra strongly depend on the applied potential, electrode materials, coverage of adsorbates and coadsorbed species, and are too complicated to be clearly interpreted in most of cases.[6,7] For instance, with the Stark tuning slope (STS), the slope of the vibrational frequency as a function of the applied potential, it is difficult to precisely quantify potential-dependent behaviours of electroadsorption. It is very difficult to quantitatively interpret the observed spectral features including potential-dependent vibrational frequency and spectral intensity, even from model systems such as single-crystal electrode/liquid interfaces. We have developed a method to combine computational vibrational spectroscopy tools with interfacial electrochemical models to accurately calculate the infrared and Raman spectra.
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