Electrocatalyst Promises Higher Selectivity

March 27, 2014
Highly selective catalyst can electrochemically convert carbon dioxide (left) to carbon monoxide with 92% efficiency.

A highly selective nano-porous silver electrocatalyst converts carbon dioxide to carbon monoxide with 92% efficiency, and is 3,000 times more active than polycrystalline silver, say its developers at the University of Delaware, Newark, Del. The resulting CO can be used as an industry feedstock for producing synthetic fuels, while reducing industrial CO2 emissions by as much as 40%, the researchers add.


Figure 1. Highly selective catalyst can electrochemically convert carbon dioxide (left) to carbon monoxide with 92% efficiency. Source: University of Delaware.

"Our catalyst could help the chemical industry to convert the CO2 gas produced from their plants into CO, an important feedstock for many existing chemical processes. As CO2 emission becomes restricted, this technology could be important for many current chemical processes," says Feng Jiao, assistant professor of chemical and biomolecular engineering and the project's lead researcher.The electrocatalyst's exceptionally high activity likely is the result of its extremely large and highly curved internal surface, which is approximately 150 times larger and 20 times intrinsically more active than polycrystalline silver, he says.The active sites on the curved internal surface require only a small voltage to overcome the activation energy barrier needed to drive the reaction, adds Jiao. By optimizing the catalyst and operating conditions, he believes it's possible to achieve selectivity close to 100%. A recent Nature Communications article provides more details.A key challenge is integrating the catalyst into a full-scale device. Jiao says major hurdles include the fabrication and implementation of large electrodes for use in pilot testing and the interfacial issues dealing with depositing this catalyst on a current connector typically found in a flow electrolysis cell.He expects integrating the catalyst into a device suitable for long-term testing likely will take a year or two, and once completed, the researchers will begin testing on a pilot-plant scale.However, scaling up production could pose other challenges such as long-term stability and resistance to contaminants in the CO2 feed stream, Jiao admits.The team also is working on several potential approaches to enhance the catalyst's mechanical strength. "It is feasible to achieve a catalyst as robust and strong as the bulk polycrystalline silver," he believes.Jiao encourages those interested in this technology to contact him; a few companies already have expressed interest in cooperating on further development, he says."Selective conversion of CO2 to CO is a promising route for clean energy, but it is a technically difficult process to accomplish. We're hopeful that the catalyst we've developed can pave the way toward future advances in this area," Jiao concludes.

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