The development of new energy storage technologies is central to solving the
challenges facing the widespread use of renewable energies. An option is the
reduction of carbon dioxide (CO2) into carbon-based products which can be
achieved within an electrochemical cell. Future developments of such processes
depend on the availability of cheap and selective catalysts at the electrode.
Here we show that a unique well-characterized active electrode material can be
simply prepared via electrodeposition from a molecular copper complex
precursor. The best performances, namely activity (150 mV onset overpotential
and 1 mA cm−2 current density at 540 mV overpotential), selectivity (90%
faradaic yield) and stability for electrocatalytic reduction of CO2 into
formic acid in DMF/H2O (97 : 3 v/v) have been obtained with the
[Cu(cyclam)](ClO4)2 complex (cyclam = 1,4,8,11-tetraazacyclotetradecane) as
the precursor. Remarkably the organic ligand of the Cu precursor remains part
of the composite material and the electrocatalytic activity is greatly
dependent on the nature of that organic component.