ACS Energy Letters which describes the technique. “These protons were exactly what we needed to convert the carbonate back into CO2 gas.” Their electrolyzer also contains a silver-based catalyst that immediately converts the CO2 produced into a gas mixture known as syngas. Syngas is a common chemical feedstock for the well-established Fischer-Tropsch process, and can be readily turned into a wide variety of products, including jet fuel and plastic precursors. “This is the first known process that can go all the way from carbonate to syngas in a single step,” says Sargent. While many types of electrolyzers have been used to convert CO2 into chemical building blocks, none of them can deal effectively with carbonate. Furthermore, the fact that CO2 dissolved in liquid turns into carbonate so readily is a major problem for existing technologies. “Once the CO2 turns into carbonate, it becomes inaccessible to traditional electrolyzers,” says Li. “That’s part of the reason why they have low yields and low efficiencies. Our system is unique in that it achieves 100% carbon utilization: no carbon is wasted. It also generates syngas as a single product at the outlet, minimizing the cost of product purification.” In the lab, the team demonstrated the ability to convert carbonate to syngas at an overall energy efficiency of 35%, and the electrolyzer remained stable for more than six days of operation. Sargent says that more work will be needed to scale up the process to the levels needed for industrial application, but that the proof-of-concept study demonstrates a viable alternative path for direct-air carbon capture and utilization. “It goes a long way toward answering the question of whether it will ever be possible to use air-captured CO2 in a commercially compelling way,” he says. “This is a key step toward closing the carbon loop.” This article appeared on the EurekaAlert website at https://eurekalert.org/pub_releases/2019-05/uotf-foo052719.php]]>