UC Davis

Electrocatalytic water oxidation is a key transformation in many strategies designed to harness solar energy and store it as chemical fuels. Half of the overall water-splitting reaction, it is kinetically slow and requires significant overpotentials to match the current efficiency of hydrogen electrodes. Understanding the mechanisms of the best electrocatalysts for water oxidation has been a fundamental chemical challenge for decades, and progress has been made using in situ methodologies. Here, we quantitate evolved dioxygen isotopologue composition via gas-phase EPR spectroscopy to elucidate the mechanisms of water oxidation on metal oxide electrocatalysts with high precision. Isotope fractionation is paired with computational and kinetic modelling, showing that this technique is sensitive enough to differentiate O-O bond forming steps. Strong agreement between experiment and theory indicates that for the layered double hydroxide—one of the best earth-abundant electrocatalysts to be studied—water oxidation proceeds via a dioxo coupling mechanism rather than a hydroxide attack. EPR detection of O2 provides new information about perhaps the most important chemical reaction for sustaining a liveable planet.In addition to the work with water oxidation and O2 EPR, I have worked on multiple collaborations by assisting various research groups with CW EPR and pulsed EPR. I herein present published work done with T. Don Tilley’s group at UC Berkeley, characterizing an intermediate in a silicide compound transformation. I also present unpublished work done with Elizabeth Nolan’s group at MIT, studying the effects of adding Ca to a Cu centered calprotectin and how it affects the number of His ligands coordinating to the Cu center. I also present submitted work done with Chris Chang’s group at UC Berkeley, characterizing Cu uptake in RAD23B.