A new approach was developed that utilizes a series of catalytic reactions to electrochemically reduce carbon dioxide to methane — the main ingredient in natural gas — eliminating an intermediate step usually needed in the reduction process.
To convert carbon dioxide into valuable fuels, one has to start with a surface made of copper, which can be used to reduce carbon dioxide into carbon monoxide. It can then be further transformed into substances such as methane. This process is relatively simple but requires two reactors and costly separation and purification steps. The new approach is a one-pot catalysis system — by adding carbon dioxide, a series of chemical reactions will happen without the need to stop and add more chemicals.
Special nanostructured silver surfaces were added to the copper surfaces. The silver portion attracts carbon monoxide molecules, which then migrate to the copper portion and reduce to methane. The system yields a higher concentration of methane than copper-only systems. The approach enables several steps of the reaction to occur in one system. Researchers systematically modified the composition — the silver-to-copper ratio — in the structure.
Previous attempts to combine copper with precious metal in this way have failed; instead, the researchers developed a special type of electrode structure that enabled the system.