(69a) Copper-Graphite Nanocomposite Electrodes for the Electrochemical Reduction of Carbon Dioxide to Methanol

One proposed solution to the energy problem is to capture carbon dioxide emitted from the combustion of fossil fuels and then convert carbon dioxide back to liquid fuels, using energy obtained from renewable sources.  In particular, the conversion of carbon dioxide to methanol via the electrochemical reduction of carbon dioxide is one of the high-potential processes that could produce liquid products that can be directly used as a fuel or easily converted to different types of fuels. The electrochemical reduction of carbon dioxide is thermodynamically possible and can produce different products, among which is methanol. One of the challenges that this nascent technology faces is the lack of stable electrode material that would offer long hours of operation before deactivation. Copper was found to be a good candidate for the production of methanol, but it is easily oxidized and its stability is limited.

To this end, the goal of our study is to synthesize copper-graphite nanocomposite material through powder technology techniques to be used as electrodes for the electrochemical reduction of carbon dioxide to methanol. Nano-copper, prepared via the electroless deposition technique, was mixed with 6 different graphite powder concentrations (2.5, 5, 7.5, 10, 20, 30 wt%) . The mixtures were uniaxially pressed at 700 MPa and sintered at 1000 ^oC. The synthesized electrodes were characterized via FE-SEM and XRD to ensure the homogeneity of the material. The electrodes were used in an electrochemical cell, which contained potassium hydrogen carbonate as the electrolyte. The open circuit voltages for the different electrodes in carbon dioxide and nitrogen atmospheres were measured.  Also, the applied voltage – current plots were made under the two atmospheres. Nernst plots were made for all six electrode-electrolyte pairs and were compared with that for the pure copper electrode. In addition, stability tests were performed on the different electrode compositions. The initial results are promising as they show equivalence of the nanocomposites with the pure copper electrodes in terms of carbon dioxide reduction potential. Yet, their stability is significantly improved.