Theoretical and Experimental Co {\it K}-edge XAS of Layered Cobalt Oxides Catalysts

The efficient water oxidation for fuel production from sunlight, with the use of earth-abundant catalysts, is of high importance to photo-fuel cell research. Recent experimental investigations of Co-oxide based catalysts under active conditions of water oxidation show evidence for layered cobalt-oxide structures with possible cation intercalation from electrolyte. To gain insight into our experimentally measured Co {\it K}-edge x-ray absorption spectra of Co-oxide anodes compared to spectra of powder standards such as CoOOH, Co(OH)$_2$ and Co$_3$3O$_4$, we perform theoretical investigations of these spectra. We employ density functional theory plus U (DFT+U) calculations of {\it K}-edge x-ray absorption spectra using core-hole approach which has been shown to accurately capture the pre-edge features of similar $\alpha$-LiCoO$_2$ [1]. We consider $\beta$-CoOOH, $\alpha$-KCoO$_2$, $\gamma$-K$_{0.5}$CoO$_2$ structures as possible candidates.