Overview
Sungkyunkwan University(SKKU) research team led by Professor Young Dok Kim from the Department of Chemistry has developed a novel bismuth-based nanosheet catalyst featuring abundant micro-scale "nano-defects" (oxygen vacancies) engineered using cerium (Ce x), a rare-earth metal. Utilizing this catalyst, the team successfully converted carbon dioxide (CO2)—a major greenhouse gas—into formate, a high-value chemical compound with extensive industrial applications, achieving exceptional conversion efficiency.

Background & Challenges
To address global warming, significant research worldwide has focused on CO2 electroreduction technology, which captures carbon dioxide from the air and uses renewable electricity to convert it into useful chemicals. Among various potential end-products, formate is particularly attractive due to its high energy-storage capacity and versatile applications across industries, including eco-friendly hydrogen fuel cells, pharmaceuticals, and chemical manufacturing. However, conventional catalysts have faced key limitations: slow reaction rates and difficulties in releasing products from the catalyst surface, leading to sharp efficiency drops under high-current conditions required for large-scale industrial production.

Key Innovation
Professor Young Dok Kim’s team resolved this bottleneck by designing a two-dimensional (2D) nanosheet catalyst structure rich in micro-pores and nano-scale defects, resembling a thin sheet of paper or a sponge. During the synthesis process, cerium oxide components migrate from the interior of the nanosheet toward the surface, inducing the creation of abundant, highly beneficial nano-defects across the surface.
The synergistic effect between these engineered nano-defects and cerium allows key reaction intermediates to bind to the catalyst surface with optimal strength, while facilitating the rapid release of the final formate product. This mechanism significantly accelerates the overall reaction rate and effectively suppresses hydrogen evolution—an unwanted side reaction that typically hinders CO2 reduction.

Experimental Results
• High Faraday Efficiency: The newly developed catalyst achieved a formate Faradayefficiency of 96.2% in standard laboratory setups (H-type cells).
• Industrial Flow Cell Performance: In flow cell configurations that replicate industrial high-current density demands, it demonstrated an outstanding 96.8% Faraday efficiency.
• Long-Term Operational Stability: Under high current density conditions, the catalyst maintained a high efficiency of over 85% for 115 hours without notable degradation, proving its robust long-term durability.

(Note: Faraday efficiency refers to the proportion of electrical charge consumed that goes directly into producing the targeted chemical product.)

Researcher Insights
"This study represents an innovative strategy that simultaneously achieves high efficiency and stability in turning carbon dioxide into a valuable resource by precisely controlling micro-defects within the catalyst," said Professor Young Dok Kim. "Building upon this technology, we plan to continue developing catalysts for converting CO2 into eco-friendly, higher-value multi-carbon compounds, contributing directly to realizing carbon neutrality."

Funding & Publication
This research was supported by the Basic Research Laboratory (BRL) Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT, as well as the University Key Research Institute Support Program funded by the Ministry of Education. The findings were published online on the 10th in the Chemical Engineering Journal, a world-renowned academic journal in chemical engineering.