High-temperature solid oxide cells (SOCs) offer one of the most efficient and versatile routes for producing electric power and H2. However, the practical use of nanomaterials in SOCs has been limited by their lack of thermal stability. In this study, we present an infiltration technique that enables the in situ synthesis of extremely small, thermally stable perovskite (Sm0.5Sr0.5)CoO3 nanocatalysts on the inner surface of porous SOC electrodes. We identified certain impurity phases, such as SrCO3, that cause fatal degradation and eliminated them using a rational complexation strategy optimized for individual constituent cations. Consequently, we fabricated ∼ 20 nm diameter, highly pure, single-phase nanocatalysts that achieved more than double the performance of a cell with standard (La,Sr)(Co,Fe)O3– and (La,Sr)CoO3-based air electrode. The cells stably operated during long-term tests in both the power generation and H2 production modes, with negligible degradation. Furthermore, we successfully scaled up this process to fabricate large-scale commercial cells using a fully automated process. The key findings of this study will resolve critical barriers with high-temperature nanomaterials and accelerate the commercialization of SOC technology.

Atomically dispersed catalysts provide excellent catalytic properties and atom utilization efficiency, but their high-temperature application has been limited by their low thermal stability. Herein, we report atomically dispersed Pt catalysts that are both highly active and thermally stable in fuel cells and electrolyzers operating above 600 °C. We developed a urea-based chemical synthetic method that strongly anchors atomic-scale Pt species on the surface of ceria nanoparticles and prevents their agglomeration at high temperatures. Doping the ceria with gadolinia further enhances their catalytic properties by increasing the oxygen vacancy concentration and promoting the oxygen exchange kinetics. This process enables in situ synthesis within the porous electrode of realistic solid oxide cells and significantly improves the power output and H2 production rate in fuel cell and electrolysis modes, respectively. Furthermore, this electrode stably operated without noticeable degradation during a long-term evaluation, thus proving the excellent thermal stability of atomically dispersed Pt/ceria catalysts.

- Green ammonia is a carbon-free energy carrier and storage medium synthesized using green hydrogen and an active catalyst. 

- The catalytic activity of ammonia synthesis can be improved by controlling the geometry and electronic structure of the active species through an exsolution process.

- Ru nanoparticles exsolved on a BaCe0.9Y0.1O3-δ support exhibit high activity and uniform size distribution, and are well-anchored to the support with in-plane epitaxy. The electronic structure of Ru is modified by in situ Ba promoter accumulation.

(Note that this is a summary of the abstract using chatGPT)

암모니아(NH3) 에너지 밀도가 높고 연소시 이산화탄소 배출이 없어 각광받는 수소 (혹은 에너지) 운반체이다. 암모니아를 연료로 사용하여 전기 에너지를 생산할 수 있는 기술 중 고체산화물 연료전지 (SOFC) 가 있다. SOFC는 니켈이 풍부한 연료극 구조와 높은 작동 온도를 가지고 있어 암모니아 연료를 셀에 직접 주입하여 사용할 수 있다. 750도 이상의 높은 작동온도를 가지는 기존의 SOFC는 별도의 셀구조 변화 없이 직접 암모니아 운전이 가능하다. 작동 온도를 낮추면 암모니아 연료 SOFC의 응용 분야가 다양해질 수 있어 그에 대한 연구를 진행하였다. 본 연구에서는 500~650°C 온도에서 두 가지 유형의 박막형 SOFC(TF-SOFC)를 사용하여 직접 암모니아 작동을 테스트하고 이를 상용 SOFC와 비교하였다. NiO-GDC 연료극을 가진 TF-SOFC는 650도에서 1330mW cm-2의 최대 전력 밀도를 보였고 이는 현재까지 보고된 최고수준의 암모니아 연료 SOFC 성능이다. 그러나 NH3 운전시의 성능은 동일한 셀을 이용한 H2 운전시의 성능과 큰 차이가 존재했다. 전기화학 임피던스 분석, 암모니아 전환율 분석 및 2D multiphysics 모델링을 통해 저온에서 낮은 암모니아 전환율이 성능 격차의 주요 원인임을 확인하였다. 따라서 암모니아 전환율을 높일 수 있는 암모니아 분해 촉매를 도입하면 저온형 직접 암모니아 SOFC의 성능을 개선시킬 수 있으리라 기대된다. 

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