Energy and chemicals from the selective electrooxidation of renewable diols by organometallic fuel cells

The OrganoMetallic Fuel Cell (OMFC) is a Direct Alcohol Fuel Cell (DAFC) which employs a rhodium complex supported on carbon black as anodic electrocatalyst: Rh[(trop2NH)PPh3]OTf/KtjBk (trop2N=bis(5-H-dibenzo[a,d] cyclohepten-5-yl)-amide; KtjBk = Ketjen Black EC 600 JD) [1]. In contrast to established DAFCs technologies based on metal nanoparticles, in OMFCs every single metal atom is catalytically active and thereby reduces the metal loading of fuel cell electrodes by several orders of magnitude. Because the performance of the metal complexes can be optimized based on established methods of synthetic organometallic and coordination chemistry, the approach via OMFC's - though in its infancies - should allow to truly design electrodes which in principle can operate with earth-abundant, inexpensive metals. The [Rh(OTf)(trop2NH)(PPh3)]/KtjBk based OMFC catalyses the selective electrooxidation of renewable diols, such as ethylene glycol and 1,2-propanediol, to their corresponding monocarboxylic compounds, simultaneously providing high power densities and chemicals of industrial importance. Therefore the OMFCs can achieve cogeneration of electricity and valuable chemicals in a highly selective electrooxidation from diol precursors