ENG

Author: 공과대학 교학팀

2023. 07. 18

Electrochemical catalyst for CO2 conversion to Produce valuable chemicals for Carbon Neutrality

Electrochemical CO2 reduction reaction for sustainable chemical cycle   Yun Jeong Hwang 1*   1Department of Chemistry, Seoul National University (SNU), Republic of Korea E-mail address: yjhwang1@snu.ac.kr       Electrochemical CO2 reduction (CO2R) can be integrated with renewable energy sources and water can be utilized as a direct proton source which is promising to provide a sustainable net-zero carbon cycle. However, using water as the proton source causes undesired competitive hydrogen evolution reaction (HER), and thus it is crucial to control selectivity for CO2R. Various metal-based electrocatalysts have been investigated to convert CO2 to CO, formate, ethylene, ethanol, or other C2+ chemicals. Multiple reaction pathways and reaction intermediates are shared and thus product distribution is sensitively affected by nanostructured active sites both in a conventional H-cell as well as a membrane electrode assembly (MEA) electrolyzer. Understanding intrinsic and extrinsic factors are important to achieve selective CO2R to target product. In this talk, I will discuss efforts to understand the morphology changes of the nanocatalyst. Cu-based catalysts can experience morphology changes during the pre-treatment step and reduction reaction conditions, and increasing the domain boundaries can contribute to enhanced activity for CO2R over HER. In the GDE-based membrane-electrode-assembly (MEA) electrolyzer, increasing the surface roughness and grain boundaries have shown high selectivity for C2+ chemicals similar to the conventional H-Cell type electrolyzer. Meanwhile, from a practical point of view, researchers also propose direct conversion of the captured CO2 by the electrochemical process. We demonstrate that a Ni-N-C catalyst has high selectivity for electrochemical CO2 conversion to CO production due to the relatively high activation energy for HER compared to that of the CO2R-to-CO reaction. This contributes to increasing CO2 conversion efficiency even under low concentrations of available CO2 gas. In addition, the Ni-N-C was found to have low sensitivity to the type of alkali metal cation or the type of amine. Modulation of the catalyst-electrolyte interface can provide new opportunities to promote challenging catalytic reactions....

2023. 05. 24

The future of mobility materials

With the recent emergence of future mobility developments such as Urban Air Mobility (UAM), there has been an increasing interest in the development of materials suitable for these advancements. What might the specific requirements be for materials used in future mobility? Firstly, lightweight materials will be...

2023. 03. 13

Electro-Mechanically Responsive Ionoelastomer Heterojunctions

Electro-Mechanically Responsive Ionoelastomer Heterojunctions   Hyeong Jun Kim   Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, South Korea     Soft solids capable of conducting ions offer promise for the design of entirely new classes of highly deformable and bio-inspired devices. While resistive and capacitive ionic circuit elements are...

2023. 05. 18

Applications of CFD in designing engineering objects

When shape optimization of engineering objects is conducted in the aerodynamic prospective, it is necessary to examine objects’ performance at various designs. One of the most widely used shape design methods in this purpose is to parameterize the given shape (frequently called the baseline design or...

2023. 07. 09

Electrocatalysis on Atom-Precise Metal Nanoclusters

  Electrocatalysis on Atom-Precise Metal Nanoclusters   Dongil Lee   Yonsei University, Seoul 03722, Republic of Korea  dongil@yonsei.ac.kr   Accurate identification of active sites is critical for elucidating catalytic reaction mechanisms and developing highly efficient and selective electrocatalysts. In the first part of my presentation, I will talk about atomic-level identification of active sites for the electrochemical CO2 reduction reaction (CO2RR) using atomically well-defined metal nanoclusters (NCs) Au25(SR)18 and Ag25(SR)18 (SR = thiolate). While both NCs produced CO as a main CO2RR product, the Au25 NC exhibited a significantly higher CO2RR activity than the Ag25 NC. Theoretical and operando studies revealed that the CO2RR limiting potential for the Au25 NC was significantly smaller than that for the Ag25 NC, while both NCs contained the partially dethiolated metal sites as the active sites. Active-site engineering was performed by replacing the Ag12(SR)18 shell of the Ag25(SR)18 NC with the Au12(SR)18 shell to generate a core-shell AuAg12@Au12(SR)18 NC, which exhibited stable CO2-to-CO electroreduction at a commercially relevant current density of 200 mA/cm2 and a full-cell potential of 2.1 V in a zero-gap CO2 electrolyzer. In the second part, I will discuss the effects of metal doping and ligand engineering on the hydrogen evolution reaction (HER) activities of gold and silver NCs. Studies of electrocatalysis by the rationally engineered NCs provide many important design principles for the development of electrocatalysts with tailored structure and adsorption energy. These principles are illustrated with NC-based electrocatalysts for water splitting and CO2 conversion.  ...