Heterometallic Lanthanide–Titanium Oxo Clusters: A New Family of Water Oxidation Catalysts

We report the synthesis and photoelectrochemical activity of three lanthanide–titanium oxo clusters (LTOCs), formulated as [Ln 8 Ti 10 (μ 3 -O) 14 (tbba) 34 (Ac) 2 (H 2 O) 4 (THF) 2 ]·2Htbba [Ln = Eu ( 1 ), Sm ( 2 ), and Gd ( 3 ); Htbba = 4- tert -butylbenzoic acid; Ac – = acetate]. These stable compounds are efficient catalysts of photoelectrochemical water oxidation with high turnover numbers (7581.0 for 1, 5172.4 for 2, and 5413.0 for 3 ) and high turnover frequencies (2527.0 for 1, 1724.1 for 2, and 1804.0 for 3 ). The differences in the photoelectrochemical activity among these three compounds may be related to the differences in their band gaps. This work shows that the heterometallic LTOCs provide a tunable platform for the design of highly effective water oxidation catalysts.