Polymeric binuclear ruthenium complex as efficient electrocatalyst for oxygen evolution reaction

A robust polymeric material constituted by chains of binuclear aqua ruthenium terpyridylphenanthroline complexes connected through benzene ring meta-positions, exhibiting an unusual two electrons and two protons PCET (proton-coupled electron transfer) process and enhanced oxygen evolution reaction (OER) activity, is described. The catalytic active [RuVO] species is generated at potentials more positive than +1.5 V (NHE) in the poly-[{Ru(H2O)(phen)}2(tpy2ph)] film, as confirmed by the rise of the ruthenyl (RuVO) stretching band at 810 cm−1 in the Raman spectrum, and the clear change to a higher activity regime as confirmed by EIS. Faradaic efficiency for OER as high as 39% was achieved at +1.8 V, indicating that poly-[{Ru(H2O)(phen)}2(tpy2ph)] is one of the most active ruthenium terpyridine complexes ever prepared. The synthesis and characterization of the monomeric binuclear [{RuCl(Clphen)}2(tpy2ph)]2+ and its respective [{Ru(H2O)(Clphen)}2(tpy2ph)]4+ aqua complex are also fully described.