Suryansh Singh, Hanna Lyle, Luca D'Amario, Elena Magnano, Ilya Vinogradov*, and Tanja Cuk*
J. Am. Chem. Soc., 2021, 143, 39, 15984, DOI:听
The oxygen evolution reaction (OER) from water requires the formation of metastable, reactive oxygen intermediates to enable oxygen鈥搊xygen bond formation. Conversely, such reactive intermediates could also structurally modify the catalyst. A descriptor for the overall catalytic activity, the first electron and proton transfer OER intermediate from water, (M鈥揙H*), has been associated with significant distortions of the metal鈥搊xygen bonds upon charge-trapping. Time-resolved spectroscopy of in situ, photodriven OER on transition metal oxide surfaces has characterized M鈥揙H* for the charge trapping and the symmetry of the lattice distortions by optical and vibrational transitions, respectively, but had yet to detect an interfacial strain field arising from a surface coverage of M鈥揙H*. Here, we utilize picosecond, coherent acoustic interferometry to detect the uniaxial strain normal to the SrTiO3/aqueous interface directly caused by Ti鈥揙H*. The spectral analysis applies a fairly general methodology for detecting a combination of the spatial extent, magnitude, and generation time of the interfacial strain through the coherent oscillations鈥� phase. For lightly n-doped SrTiO3, we identify the strain generation time (1.31 ps), which occurs simultaneously with Ti鈥揙H* formation, and a tensile strain of 0.06% (upper limit 0.6%). In addition to fully characterizing this intermediate across visible, mid-infrared, and now GHz-THz probes on SrTiO3, we show that strain fields occur with the creation of some M鈥揙H*, which modifies design strategies for tuning catalytic activity and provides insight into photo-induced degradation so prevalent for OER. To that end, the work put forth here provides a unique methodology to characterize intermediate-induced interfacial strain across OER catalysts.
听