Electrocatalytic water oxidation by a molecular catalyst incorporated into a metal–organic framework thin film
A molecular water oxidation catalyst, [Ru(tpy)(dcbpy)(OH2)](ClO4)2 (tpy = 2,2′:6′,2′′-terpyridine, dcbpy = 2,2′-bipyridine-5,5′-dicarboxylic acid) , has been incorporated into FTO-grown thin films of UiO-67 (UiO = University of Oslo), by post-synthetic ligand exchange. Cyclic voltammograms (0.1 M borate buffer at pH = 8.4) of the resulting UiO67-[RuOH2]@FTO show a reversible wave associated with the RuIII/II couple in the anodic scan, followed by a large current response that arises from electrocatalytic water oxidation beyond 1.1 V vs. Ag/AgCl. Water oxidation can be observed at an applied potential of 1.5 V over the timescale of hours with a current density of 11.5 μA cm−2. Oxygen evolution was quantified in situ over the course of the experiment, and the Faradaic efficiency was calculated as 82%. Importantly, the molecular integrity of  during electrocatalytic water oxidation is maintained even on the timescale of hours under turnover conditions and applied voltage, as evidenced by the persistence of the wave associated with the RuIII/II couple in the CV. This experiment highlights the capability of metal organic frameworks like UiO-67 to stabilize the molecular structure of catalysts that are prone to form higher clusters in homogenous phase.
- This article is part of the themed collection: Dalton Transactions Inorganic Symposia