A new Ru oligomer
of formula {[Ru
II
(bda-κ-N
2
O
2
)(4,4′-bpy)]
10
(4,4′-bpy)},
10
(bda is [2,2′-bipyridine]-6,6′-dicarboxylate
and 4,4′-bpy is 4,4′-bipyridine), was synthesized and
thoroughly characterized with spectroscopic, X-ray, and electrochemical
techniques. This oligomer exhibits strong affinity for graphitic materials
through CH−π interactions and thus easily anchors on
multiwalled carbon nanotubes (CNT), generating the molecular hybrid
material
10@CNT
. The latter acts as a water oxidation
catalyst and converts to a new species,
10′(H
2
O)
2
@CNT
, during the electrochemical oxygen evolution process
involving solvation and ligand reorganization facilitated by the interactions
of molecular Ru catalyst and the surface. This heterogeneous system
has been shown to be a powerful and robust molecular hybrid anode
for electrocatalytic water oxidation into molecular oxygen, achieving
current densities in the range of 200 mA/cm
2
at pH 7 under
an applied potential of 1.45 V vs NHE. The remarkable long-term stability
of this hybrid material during turnover is rationalized based on the
supramolecular interaction of the catalyst with the graphitic surface.