NETL researchers focused on developing carbon dioxide (CO₂) conversion technologies recently demonstrated that the material on which a catalyst is affixed, called a support, can have a dramatic impact on its performance. The discovery could lead to improved energy efficiency, boosted catalyst performance and a reduction the amount of expensive metallic catalyst materials needed for these systems, which will be crucial for meeting the nation’s decarbonization goals.

The team leveraged NETL’s unique surface science equipment and computational modeling capabilities to carefully grow, analyze and quantify interactions between small silver particles and carbon catalyst supports. The results of the research have been published in the high-impact journal ACS Catalysis as a freely available, open access article.

“By tuning the catalyst-support interactions, we were able to ‘turn-off’ competing reactions and boost CO₂ conversion selectivity to nearly 100%,” said NETL’s lead author Xingyi Deng. “These catalyst supports were previously thought be inert and to have little effect on performance. This research has opened a new avenue for creating active and selective nanocatalysts.”

When they made their discovery, the multi-disciplinary NETL team was investigating how to overcome problems associated with a decrease in selectivity as the particle size of catalysts based on gold, copper and silver (coinage metals) decreases.

“Typically, when designing a nanocatalyst, we can reduce the particle size to achieve higher surface area to maximize catalyst utilization,” said co-authors Dominic Alfonso and Douglas Kauffman. “However, this is not the case for electrochemical CO₂ reduction using catalysts based on coinage metals. In this case, very small particles tend to lose product selectivity below a diameter less than three nanometers. So, we started looking at carbon catalyst supports to see if they could enhance electrocatalytic reactions, thus breaking the size-dependent selectivity trend.”

Because carbon is often used as a catalyst support, there has been considerable interest in establishing electronic metal support interactions (EMSIs) between carbon-based supports and metal/oxide nanostructures to enhance interactions.

In this research, the NETL team found that by creating defects in the carbon supports, which exposes more surface area, the metal-carbon interactions between the supports and small-diameter (less than two nanometers) silver particles improved catalytic activity. The team further demonstrated the importance of EMSIs by growing small silver nanoparticles at the defect sites of a commonly used carbon black (CB) support. The CB-supported silver nanoparticles also exhibited EMSIs and demonstrated high selectivity during six hours of electrolysis.

“Knowing how integral EMSIs are to designing a highly active and selective silver nanocatalyst on a carbon-based support, we believe that this insight could be used as justification for investigating how EMSIs might impact other catalysts used for carbon conversion such as tin, bismuth and copper,” Deng said.

NETL is a U.S. Department of Energy national laboratory that drives innovation and delivers technological solutions for an environmentally sustainable and prosperous energy future. By its world-class talent and research facilities, NETL is ensuring affordable, abundant and reliable energy that drives a robust economy and national security, while developing technologies to manage carbon across the full life cycle, enabling environmental sustainability for all Americans.