Electrochemical reduction of carbon dioxide to potential carbon sources has attracted a huge attention as an ideal reaction to reduce carbon dioxide and produce new energy resources. To enhance the electrochemical reduction, metal nanoparticles are one of the best catalysts due to their large surface area. Major challenges in this field are overcoming the large overpotential and controlling the selectivity among various products. One potential approach is using alloy nanoparticles, which change binding energies of intermediates on the catalyst surface and enhance the reaction kinetics for $CO_2$ reduction.
In Chapter 1, the electrochemical $CO_2$ reduction reaction using metal catalyst, is introduced. Major products and thermodynamic reduction potentials of electrochemical $CO_2$ reduction are introduced.
In Chapter 2, the reaction system for electrochemical $CO_2$ reduction with metal nanoparticles is demonstrated. Ag nanoparticles with the average diameter of 5 nm on carbon supports were used as a standard catalyst for this system. The catalyst, 5 nm Ag/C, was employed for the electrochemical $CO_2$ reduction. We confirmed that the catalytic efficiency of the 5 nm Ag/C was reproduced in the new system.
In Chapter 3, new designed nanocatalyst are introduced to the electrochemical $CO_2$ reduction system. Silver-palladium nanoalloys having various ratios on carbon supports (AgPd/C) were synthesized through a one-pot method. The resulting AgPd/C was used as a catalyst for $CO_2$ reduction. The catalytic activity was highly dependent upon the catalyst composition.
As a result, we successfully established reaction system for the accurate measurement of electrochemical $CO_2$ reduction. We synthesized the AgPd/C nanoalloy by the new one-pot method, and proposed the different insight of AgPd alloying effect for $CO_2$ electro-reduction.
이산화탄소를 환원시켜 탄소 화합물을 만드는 전기화학반응은 새로운 에너지 생산에 대한 연구로 각광받고 있다. 반응성을 높이기 위해, 넓은 표면적을 가진 금속 나노 입자는 좋은 촉매로, 큰 과전압 줄이기와 생산물의 선택성 조절이 중요한 과제이다. 나노 합금을 이용하게 되면, 표면 촉매와 반응 중간체와의 결합 에너지를 조절하여 반응 속도를 증진시킬 수 있다. 1장에서는 기존에 알려진, 금속 촉매를 이용한 이산화탄소 환원 전기화학반응에 대한 연구가 소개되어 있다. 2장에서는 전기화학반응을 위한 체계를 구축하는 것과 은 나노 촉매를 이용한 재현 실험이 있다. 3장에서는 은-팔라듐 나노 합금을 탄소 지지체에 직접 성장시키는 방식으로 합성하여, 이산화탄소 전기화학반응을 보았고, 촉매 활성이 합금 원소 구성에 따라 달라짐을 알 수 있었다. 결론적으로 이산화탄소 전기화학반응을 할 수 있는 체계를 구축하였고, 새로운 촉매를 합성하여 그 반응을 볼 수 있었다.
