A Million Turnover Molecular Anode for Catalytic Water Oxidation

Molecular ruthenium‐based water oxidation catalyst precursors of general formula [Ru(tda)(Li)2] (tda2− is [2,2′:6′,2′′‐terpyridine]‐6,6′′‐dicarboxylato; L1=4‐(pyren‐1‐yl)‐N‐(pyridin‐4‐ylmethyl)butanamide, 1 b; L2=4‐(pyren‐1‐yl)pyridine), 1 c), have been prepared and thoroughly characterized. Both complexes contain a pyrene group allowing ready and efficiently anchoring via π interactions on multi‐walled carbon nanotubes (MWCNT). These hybrid solid state materials are exceptionally stable molecular water‐oxidation anodes capable of carrying out more than a million turnover numbers (TNs) at pH 7 with an Eapp=1.45 V vs. NHE without any sign of degradation. XAS spectroscopy analysis before, during, and after catalysis together with electrochemical techniques allow their unprecedented oxidative ruggedness to be monitored and verified. A million TONs: Oxidatively stable molecular water oxidation anodes reaching more than a million turnover numbers with no molecular degradation are achieved by using a ruthenium‐based molecular catalyst anchored on a multi‐walled carbon nanotube.