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This tutorial-review describes a systematic framework for selecting suitable electrolytes to improve the efficiency of resulting non-aqueous redox flow batteries. 

Abstract Substitutional lability of the terminal methoxide ligand on a Zr(IV) substituted polyoxovanadate‐alkoxide (POV‐alkoxide) via protonolysis is presented. Addition of excess water or stoichiometric 2,2,2‐trifluoroethanol results in the exchange of the terminal methoxide ligand for a hydroxide or 2,2,2‐trifluoroethoxide ligand, respectively. The lability of the terminal methoxide ligand at zirconium is leveraged to access a relatively stable terminal peroxide bound to a POV‐alkoxide supported Zr(IV) center, via addition of hydrogen peroxide adducts compatible with organic solvent. Isolation of the terminal peroxide complex allows for investigation into the impact of the sterically protected, electron‐rich POV‐alkoxide support on the activation of hydrogen peroxide at Zr(IV). While the isolated peroxide complex is inactive towards the oxidation of thioethers, the methoxy terminated Zr(IV) functions as a precatalyst for the reaction. Mechanistic analysis reveals electrophilic oxidation conditions with hydrogen peroxide substrates, with a nucleophilic parameter () of 0.09±0.02. In thioether oxidation reactions, selectivity for sulfoxide products (95–99 %) in acetonitrile is observed, suggesting the use of a reduced POV‐alkoxide prevents over‐oxidation of substrate. 

The mechanism of proton-coupled electron transfer at the surface of titanium-substituted polyoxovanadate-alkoxide clusters can be tuned by judicious selection of substrate. 

Actinide doping enhances redox chemistry of polyoxomolybdate-alkoxide clusters; the first isolable U(v) polyoxometalate cluster is reported. 

“Goldilocks” affinity of K⁺for the POV surface stabilizes reduced form of assembly for improved cycling stability! 

We report the reduction of O₂to H₂O₂viaconcerted proton–electron transfer from the terminal V(iii)–OH₂moiety of a reduced polyoxovanadate-alkoxide cluster.