Nanostructured Materials for the Electroreforming of Alcohols in Alkaline Media

The diffusion of hydrogen production by electrolytic water splitting is limited by the thermodynamic barrier of water oxidation. Hence, useful levels of hydrogen production can only be obtained with an electrical energy consumption exceeding 45 kWh kg-1H2. Electrochemical reforming overcomes such thermodynamic limitations by replacing oxygen evolution with the facile oxidation of an alternative substrate. Electrical energy savings of up to 26.5 kWh kg-1H2 can be obtained using alcohols such as ethanol, ethylene glycol, glycerol and 1,2-propandiol as compared to state of the art proton exchange membrane water electrolysis. This technology, first demonstrated using acidic membranes in adapted PEM cells was limited to MeOH as substrate. Under alkaline conditions using anion exchange membranes a much larger range of alcohols may be employed for electrochemical reforming. Because of this, electrochemical reforming under alkaline conditions can be used to exploit the partial oxidation of various polyalcohols to valuable intermediates of industrial interest. In this way, the production of hydrogen at low energy cost is combined with the bio-refinery concept for the combined production of hydrogen and fine chemicals. This is a relatively new area of research with most reports in the literature appearing over the last decade or so. On the other hand, electrochemical reforming is an exciting and growing field with potential for significant commercial development in the renewable energy and green chemistry sectors.