Measuring Theoretical Descriptors of Water Oxidation: Free Energy Differences Between Intermediates Using Time-Resolved Optical Spectroscopy

Vinogradov, Ilya; Singh, Suryansh; Lyle, Hanna; Mandal, Aritra; Cuk, Tanja

doi:10.26434/chemrxiv.13003490.v2

“…2A, phonon removed) which we have studied in a previous publication. 36 In the next three sections, we will extract the frequency (3.1), amplitude (3.2), and phase (3.3) of these oscillations and use them to link the CAWs in CC to interfacial strain generated by hole-trapping to create Ti-OH * . The OC condition will be used as a foil, in which the CAWs derive instead from high photocarrier populations.…”

Section: Resultsmentioning

confidence: 99%

“…1 represent the growth of an emissive signal associated with hole trapping and the decay exponential is associated with the decay of the valance band hole population (described below). 8,9,12,36,39 For hole trapping, we found that the average fast growth timescale was 1.2 ± 0.3 ps (fig. S6).…”

Section: Caws Frequencymentioning

confidence: 89%

“…To maintain the fluence, we measured the pulse energy before each experiment using a pyroelectric energy sensor (919E-200U-8-25K) from Newport and took into account the window's and STO's reflectivity (~20% loss). 36 For fluence calculation, we assumed the beam had a flat-top intensity profile with a diameter of the 200 µm.…”

Section: Methodsmentioning

confidence: 99%

“…More detail is provided in the SI (section S9) and in previous publications. 36 Before proceeding, we will introduce the relevant differences between OC and CC conditions in our STO system, which are summarized in fig. S11.…”

Section: Caws Amplitudementioning

confidence: 99%

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Coherent Acoustic Interferometry During the Photo-Driven Oxygen Evolution Reaction Associates Strain Fields with the Reactive Oxygen Intermediate

Singh¹,

Lyle²,

D’Amario³

et al. 2021

Preprint

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The oxygen evolution reaction (OER) from water requires the formation of meta-stable, reactive oxygen intermediates to enable oxygen-oxygen bond formation. On the other hand, 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-OH*), has been associated with significant distortions of the metal-oxygen bonds upon charge-trapping. Time-resolved spectroscopy of in-situ, photo-driven OER on transition metal oxide surfaces has characterized M-OH* for the charge trapped 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 M-OH*. Here, we utilize picosecond, coherent acoustic interferometry to detect the uniaxial strain normal (100) to the SrTiO3/aqueous interface directly caused by Ti-OH*. 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’ phase. For lightly n-doped SrTiO3, we identify the strain generation time (1.31 ps), which occurs simultaneously with Ti-OH* 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, that strain fields occur with the creation of some M-OH* modifies design strategies for tuning material properties for 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.

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“…Measurements for the phonon amplitude correlation were performed with a similar in-situ sample cell (3 mm CaF2 with 1 cm between the sample and window) and TR setup used previously. 36 For the TR setup, the pump and probe beams were derived from a regeneratively amplified Ti:sapphire laser system (Coherent Legend; Coherent, Inc., Santa Clara, CA) producing pulses with a center wavelength of 800 nm and ~200 fs temporal width (fig. S4A) at a 1 kHz repetition rate.…”

Section: Methodsmentioning

confidence: 99%

Coherent Acoustic Interferometry During the Photo-Driven Oxygen Evolution Reaction Associates Strain Fields with the Reactive Oxygen Intermediate

Singh¹,

Lyle²,

D’Amario³

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

The oxygen evolution reaction (OER) from water requires the formation of meta-stable, reactive oxygen intermediates to enable oxygen-oxygen bond formation. On the other hand, 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-OH*), has been associated with significant distortions of the metal-oxygen bonds upon charge-trapping. Time-resolved spectroscopy of in-situ, photo-driven OER on transition metal oxide surfaces has characterized M-OH* for the charge trapped 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 M-OH*. Here, we utilize picosecond, coherent acoustic interferometry to detect the uniaxial strain normal (100) to the SrTiO3/aqueous interface directly caused by Ti-OH*. 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’ phase. For lightly n-doped SrTiO3, we identify the strain generation time (1.31 ps), which occurs simultaneously with Ti-OH* 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, that strain fields occur with the creation of some M-OH* modifies design strategies for tuning material properties for 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.

show abstract

Ultrafast electronic and vibrational spectroscopy of electrochemical transformations on a metal-oxide surface during oxygen evolution from water

Cuk,

Chen,

Singh

et al. 2024

Preprint

0

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The oxygen evolution reaction (OER) from water fuels the planet through photosynthesis and is a primary means for hydrogen storage in energy technologies. Yet the detection of intermediates of OER central to the catalytic mechanism has been an ongoing challenge. This review covers the relevance of ultrafast electronic and vibrational spectroscopy of the electrochemical transformations of a metal-oxide surface undergoing OER. The electron doped SrTiO3/electrolyte is the system under review because of its high photocurrent efficiency with an ultrafast light trigger and because it allowed for detection of intermediate forms across the electromagnetic spectrum. The first part covers how the efficient catalytic reaction is triggered by ultrafast light pulses, describing the Schottky diode, the depletion layer, and Helmholtz layer under operating conditions to the extent possible. The second part covers the detection of the surface bound intermediates by transient spectroscopy. These target ultrafast (ps-ns) electron transfer from (or hole-trapping to) bound surface water species that are associated with the reactive oxygen intermediates of OER (e.g. OH*, O*). Their detection via a broadband visible probe, a mid-infrared evanescent wave, and coherent acoustic waves is then described. These target, respectively, the electronic states, the vibrational levels, and the lattice strain associated with the intermediates. The review is primarily concerned with how the measurements are made and the intermediates’ experimental spectra. The theoretical descriptions are brought in as a needed to provide context to spectra that are difficult to interpret on their own. A concluding section summarizes the essential findings and methodologies.

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Measuring Theoretical Descriptors of Water Oxidation: Free Energy Differences Between Intermediates Using Time-Resolved Optical Spectroscopy

Cited by 3 publications

References 46 publications

Coherent Acoustic Interferometry During the Photo-Driven Oxygen Evolution Reaction Associates Strain Fields with the Reactive Oxygen Intermediate

Coherent Acoustic Interferometry During the Photo-Driven Oxygen Evolution Reaction Associates Strain Fields with the Reactive Oxygen Intermediate

Coherent Acoustic Interferometry During the Photo-Driven Oxygen Evolution Reaction Associates Strain Fields with the Reactive Oxygen Intermediate

Ultrafast electronic and vibrational spectroscopy of electrochemical transformations on a metal-oxide surface during oxygen evolution from water

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