In-situ spectroscopies of mixed-metal nanosheet water oxidation catalysts made by pulsed laser ablation in liquids

Abstract

Our ability to utilize sustainable resources will be crit. in meeting the ever-increasing global energy demand in an eco-friendly manner. The most reliable and available source of sustainable energy is the sun. The biggest challenges to its practical utilization are its intermittency on earth and unequal local energy needs. As a consequence, we must find a way to convert solar energy into storable, transportable fuels. We envision a solar water splitting device that produces hydrogen fuel. Subsequent functionalization with carbon dioxide will produce liq. fuels that are carbon neutral upon combustion. Water oxidn., the more demanding half-reaction in the water splitting process, is a key component to such a working device. Earth-abundant, efficient, and robust water oxidn. catalysts need to be rationally designed based on their catalytic mechanisms. We have employed novel in-situ spectroelectrochem. techniques to identify short-lived catalytic intermediates under turnover conditions. We recently reported [NiFe]-LDH (layered double hydroxide) nanocatalyst materials that are highly active for water oxidn. [Hunter, Blakemore, Deimund, Gray, Winkler, M.ovrddot.uller, J. Soc.2014, 136, 13118] . Our in-situ IR, Raman, and UV-visible spectroscopic data in non-aq. solvents suggest that the LDH framework may support high-valent metal species. Strategic injection of substrate indicates that this transient species is quenched by water. Our isotope labeling expts. have shed light on the structure of catalytic intermediates.