Switching from fossil based to renewable power generation requires the installation of large overcapacities of wind and solar due to their intermittency. Storage or conversion possibilities are essential due the volatility of electricity. Economic feasibility is difficult when considering the low fossil energy carrier prices and the physical efficiency limitations of the processes.  Therefore, we choose to focus on high volume chemical feedstock such as Ethylene or CO, where the chemical value exceeds by far its pure heating value.

Electrocatalyts facilitate the conversion of CO₂ to valuable base chemical feedstocks – for selectivity improvements substantial advances in electrode design are required. Depending on the electro catalytic system, CO₂ can be electrochemically reduced to carbon monoxide (CO), methane (CH₄), ethylene (C₂H₄) and various other hydrocarbons even in aqueous media. CO could be obtained with faradic efficiencies over 90% at current densities exceeding the industrial necessary level of 100 mA/cm² with a total energy efficiency approaching 50%. Ethylene is more challenging due the highly complex reduction process involving 12 electrons and 8 protons. Faradic efficiencies up to 57% for ethylene at current densities above 150 mA/cm² could be obtained using in-situ-deposited nano-structured copper based electrocatalysts. In many experiments we observed a large gap in the sum of the current efficiencies of gaseous products to 100% FE. It is well known, that the electro-reduction of CO₂ also yields liquid products. This gap could be fully closed by detailed analysis of the electrolyte revealing a strongly pronounced formation of ethanol (> 20% FE) accompanied by wide range of C₁-C₃ alcohols, carboxylates and ketones in yields up to ~ 5%. To the best of our knowledge, the here reported faradaic efficiencies for ethanol above 20% in a current density regime above 150mA/cm² have been unpresent in the literature so far.  In addition time resolved parallel analysis of the gaseous and liquid  product distribution revealed striking relationships between different species i.e. the parallel formation of ethylene and ethanol.