The UV-Vis electronic absorption spectra of all three samples displayed in Figure , Supporting Information, indicate that all samples exhibit nearly identical electronic absorption properties with an optical absorption edge at ~530 nm. Therefore, we conclude that there is a negligible influence of either CoPOM-doping or the deposition of the CoPOM co-catalyst on the fundamental optical properties of our photoanodes, and all differences in photoelectrocatalytic behavior should be rather ascribed to changes in the electronic conductivity and surface catalytic properties.