Publication

Although the water oxidation cycle involves the critical step of O–O bond formation, the transition metal oxide radical thought to be the catalytic intermediate for this step has eluded direct observation. The radical represents the transformation of charge into a nascent catalytic intermediate, which lacks a newly formed bond and is therefore inherently difficult to detect.

While charge transport and surface reactivity have thus far been treated as independent phenomena, the interfacial carrier mobility could be highly dependent on reaction intermediates that carry localized charge and can hop from site to site along the surface.

Facile and reversible deposition of metal layers would enhance power and energy densities of hybrid batteries. Here, we investigate Cu2+/Cu(0) deposition on a RuO2anode and soluble Fe2+/Fe3+ oxidation on a symmetric RuO2 cathode in aqueous electrolyte.

The excited state dynamics of a d0 vanadium(V) oxido ligand-to-metal charge transfer (LMCT) complex, VOLF, were investigated via a combination of static optical and X-ray absorption (XAS) spectroscopy, transient optical absorption spectroscopy, and time-dependent density functional theory (TD-DFT). Upon excitation of the LMCT in the visible region, transient absorption data reveal that internal conversion traps the excited carrier population into a long-lived charge transfer state of 3dxy electron character, S1(dxy).

We have performed cobalt L-edge X-ray absorption spectroscopy (XAS) on important materials for photoactive catalysis, namely nanoscale cobalt polyoxometalates (Co POM) and a Co3O4 thin film. A set of Co POM analogues were studied that vary according to the position and number of cobalts within the POM structure, metal valence state, oxygen ligand coordination geometry and heteroatom identity.

Interfacial hole transfer between n-SrTiO3 and OH– was investigated by surface sensitive transient optical spectroscopy of an in situ photoelectrochemical cell during water oxidation. The kinetics reveal a single rate constant with an exponential dependence on the surface hole potential, spanning time scales from 3 ns to 8 ps over a ≈1 V increase.

The spectrum and dynamics of excited carriers in a spinel-ordered transition metal oxide, Co3O4, were investigated by both selective photoexcitation of all major optical transitions and selectively filling electronic states through an applied voltage.

We use time- and angle-resolved photoemission spectroscopy in the extreme ultraviolet to measure the time and momentum-dependent electronic structures of photoexcited K0.3MoO3.

Diamond anvil cell techniques are now well established and powerful methods for measuring materials properties to very high pressure. However, high pressure resistivity measurements are challenging because the electrical contacts attached to the sample have to survive to extreme stress conditions.