在稀释合金催化剂中的金属杂化通过降低表面流动性来促进烧结阻力
Jordan Finzel1, Audrey Dannar2, Shoutian Sun3
1Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA, USA.
将1%的 (Pt) 原子添加到铜 (Cu) 纳米粒子中,即使在高温下,也会显著减少它们的烧结. 这一发现为创造更稳定,更耐用的纳米粒子催化剂提供了一种新方法.
科学领域:
- 材料科学 材料科学 材料科学
- 催化剂是一种催化剂.
- 纳米技术纳米技术
背景情况:
- 稀释金属合金可以提高催化性能.
- 非常低度的合金元素可能会减少纳米粒子烧结,但这种现象缺乏严格的评估和机械理解.
- 对于烧结阻力的现有解释依赖于散装特性,而这些特性对于纳米粒子来说是不够的.
研究的目的:
- 研究稀 (Pt) 兴奋剂对铜 (Cu) 纳米颗粒烧结速率的影响.
- 阐明稀释合金元素影响纳米粒子稳定性的机制.
- 确定用于制造耐烧结纳米催化剂的设计原则.
主要方法:
- 在SiO2.2的支持下合成和表征1个原子%的Pt-化Cu纳米粒子 (~1-2nm直径).
- 在H2中进行高温老化研究,以评估烧结阻力.
- 扫描道显微镜 (STM) 用Pt合的Cu(110) 表面来研究原子脱离.
- 密度函数理论 (DFT) 计算以建模合金稳定性和预测耐烧结系统.
主要成果:
- 1原子% Pt添加到Cu纳米粒子 (Pt1Cu100) 显著降低了烧结速度,与Cu纳米粒子烧结为500°C相比,观察到的烧结速度最少达700°C.
- STM实验表明,在Cu{110) 表面上的稀释Pt降低了协调不足的原子的脱离率,这表明对烧结启动有局部影响.
- DFT计算证实了合金稳定性,并预测了其他耐烧结的稀释合金,确定了d状态混合化作为与表面流动性降低相关的关键因素.
结论:
- 稀释剂可以通过抑制表面原子脱离,显著降低支金属纳米颗粒的烧结速率.
- 主体-辅助剂d-状态杂交的程度是设计耐烧结合金纳米颗粒的关键描述因素.
- 这项工作为通过稀释合金开发高度稳定的纳米催化剂提供了机制框架.
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