Published: April 19, 2021

Ilya Vinogradov, Suryansh Singh, Hanna Lyle, Michael Paolino, Aritra Mandal*, Jan Rossmeisl, and Tanja Cuk*

Nature Materials, 2022, 21, 88. DOI: 10.1038/s41563-021-01118-9 

News Article:

Theoretical descriptors differentiate the catalytic activity of materials for the oxygen evolution reaction (OER) by the strength of oxygen binding in the reactive intermediate created upon electron transfer.  Recently time-resolved spectroscopy of (photo)-electrochemically driven OER followed the vibrational and optical spectra of this intermediate, denoted M-OH*.  However, these inherently kinetic experiments have not been connected to the relevant thermodynamic quantities.  Here, we discover that picosecond optical spectra of the Ti-OH* population on lightly doped SrTiO3 are ordered by the surface hydroxylation.  A Langmuir isotherm as a function of pH extracts an effective equilibrium constant relatable to the free energy difference of the first OER reaction step.  Thus, time-resolved spectroscopy of the catalytic surface reveals both kinetic and energetic information of elementary reaction steps, which provides a critical new connection between theory and experiment by which to tailor the pathway of water oxidation and other surface reactions.