Fe(III)/Fe(II) — ligand systems for use as negative half-cells in redox-flow cells

Cyclic voltammetric and controlled-potential electrolysis studies of Fe(III)/Fe(II) complexes with diethylenetriaminepentaacetic, nitrilotriacetic and ethylenediaminetetraacetic acids show that the formal potential of the iron redox couple shifts markedly to negative values. The stability and heterogeneous rate constants appear to favour the application of such systems as the negative half-cell on an all-iron flow cell.