In situ observation of nanoparticle exsolution from perovskite oxides; from atomic scale mechanistic insight to new nanostructures

Understanding and controlling the
formation of nanoparticles at the surface of functional oxide supports is
critical for tuning activity and stability for catalytic and energy conversion
applications. Here we use a latest generation environmental transmission
electron microscope to follow the exsolution of individual nanoparticles at the
surface of perovskite oxides, with unprecedented spatial and temporal resolution.
Qualitative and quantitative analysis of the data reveals the atomic scale
processes that underpin the formation of the socketed, strain-inducing
interface that confers exsolved particles their unique stability and
reactivity. This insight also enabled us to discover that the shape of exsolved
particles can be controlled by changing the atmosphere in which exsolution is
carried out and additionally, this could also produce intriguing new
heterostructures consisting of metal-metal oxide coupled nanoparticles. Our
results not only provide insight into the in situ formation of
nanoparticles, but also exemplify new dimensions for tailoring nanostructures
and nano-interfaces.

深入理解和控制功能氧化物支撑表面的纳米颗粒形成对于调节催化和能量转换应用中的活性和稳定性至关重要。本研究采用最新一代的环境透射电子显微镜，以前所未有的空间和时间分辨率追踪了钙钛矿氧化物表面的单个纳米颗粒的析出过程。对数据的定性和定量分析揭示了支撑形成嵌套、应变诱导界面的原子级过程，该界面赋予了析出颗粒独特的稳定性和反应活性。这一洞见还使我们发现，通过改变析出过程中所采用的气氛，可以控制析出颗粒的形状，并且这还可能产生由金属-金属氧化物耦合纳米颗粒组成的新颖异质结构。我们的研究结果不仅揭示了纳米颗粒的原位形成过程，而且展示了定制纳米结构和纳米界面的新维度。