| 학회 | 한국재료학회 |
| 학술대회 | 2020년 가을 (11/18 ~ 11/20, 휘닉스 제주 섭지코지) |
| 권호 | 26권 1호 |
| 발표분야 | G. 나노/박막 재료 분과 |
| 제목 | Growth Kinetics of Individual Co Particles Ex-solved on SrTi0.75Co0.25O3‑δ Polycrystalline Perovskite Thin Films |
| 초록 | Ex-solution, an in situ growth of metal nanoparticles from parent complex oxide supports has attracted intense attention due to its potential applications in the fields of high temperature catalysis and renewable energy. For the perovskite oxide (ABO3) which has been studied most intensively, transition or precious metals are incorporated into the B site of the perovskite lattice under oxidizing conditions, and they are egressed from the support upon subsequent reduction. A judicious control over the number, size, and distribution of ex-solved metal particles, a prerequisite for further improving the catalytic activity and stability, can only be achieved by understanding the kinetics of individual particle growth at varied parameters of ex-solution. Yet to date, this has not been explored, largely due to the limitations of post-growth analyses. Here, we measure the growth kinetics of individual Co particles ex-solved on SrTi0.75Co0.25O3‑δ polycrystalline thin films under a high vacuum, and at various temperatures and grain sizes using in situ transmission electron microscopy. The ex-solution preferentially occurs at grain boundaries and corners which appear essential for controlling particle density and distribution, and enabling low temperature ex-solution. The particle reaches a saturated size after a few minutes, and the size depends on temperature. Quantitative measurements with a kinetic model determine the rate limiting step, vacancy formation enthalpy, ex-solution enthalpy, and activation energy for particle growth. The ex-solved particles are tightly socketed, preventing interactions among them over 800 °C. Furthermore, we obtain the first direct clarification of the active reaction site for CO oxidation the Co-oxide interface, agreeing well with density functional theory calculations. |
| 저자 | 김봉중, 조용륜 |
| 소속 | 광주과학기술원 신소재공학부 |
| 키워드 | Ex-solution; Co particles; Growth; In situ transmission electron microscopy; Kinetic model |
