Synthesis, characterization, and water oxidation by a molecular chromophore-catalyst assembly prepared by atomic layer deposition. The “mummy” strategy

A new strategy for preparing spatially-controlled, multi-component films consisting of molecular light absorbing chromophores and water oxidation catalysts on high surface area, mesoporous metal oxide surfaces is described. Atomic layer deposition (ALD) is used to embed a surface-bound chromophore in a thin layer of inert Al2O3, followed by catalyst binding to the new oxide surface. In a final step, catalyst surface-binding is stabilized by a subsequent ALD overlayer of Al2O3. The ALD assembly procedure bypasses synthetic difficulties arising from the preparation of phosphonic acid derivatized, covalentlylinked assemblies. An ALD mummy-based assembly has been used to demonstrate photoelectrochemical dehydrogenation of hydroquinone. Electrocatalytic water oxidation at pH 8.8 is observed over a 2 hour electrolysis period and light-assisted water oxidation over a 6 hour photolysis period with O2 detected with a generator–collector electrode configuration.