Download Abstract: Enhanced photoelectrochemical CO2 reduction at

Abstract: Enhanced photoelectrochemical CO2 reduction at nanostructured electrodes
With the aim of reducing greenhouse gas concentrations while simultaneously generating
usable fuel supplies, recycling of carbon dioxide by catalytic conversion to gaseous or liquid
fuels with low over potential has received increasing interest in the past years. Similar to water
splitting, several studies have examined electro and photo catalysts for CO2 splitting. CO2 is
the highest oxidized form of carbon, therefore reduction of CO2 usually requires a high
potential, i.e. -1,9 V vs. NHE for a one electron activation. Therefore, catalysts that favour a
two electron reduction are preferable.
Metal complexes with bipyridine ligands are one of the most promising catalysts in terms of
activities and lifetimes. Up to now mainly Rhenium and Ruthenium metal catalysts have been
reported for their ability to electrochemically and photochemically catalyze the reduction of
CO2 to CO. Especially the complex Re(2,2’bipyridyl)(CO)3Cl which was reported by Lehn et
al. in 1984, demonstrated high Faradaic efficiency and no significant loss of performance from
catalyst degradation over several hours. However, up to now there exists no known catalyst that
demonstrates sufficient turn over frequencies to reduce CO2 at a rate comparable to energy
income provided by solar radiation. Nanostructured materials for the electrode-catalyst-CO2
interface could help to overcome this challenge.
Engelbert PORTENKIRCHNER
e-mail: [email protected]