Understanding catalysts strain dynamic behaviours is crucial for the development of cost-effective, efficient, stable and long-lasting catalysts. Here, we reveal in situ three-dimensional strain evolution of single gold nanocrystals during a catalytic CO oxidation reaction under operando conditions with coherent X-ray diffractive imaging. We report direct observation of anisotropic strain dynamics at the nanoscale, where identically crystallographically-oriented facets are qualitatively differently affected by strain leading to preferential active sites formation. Interestingly, the single nanoparticle elastic energy landscape, which we map with attojoule precision, depends on heating versus cooling cycles. The hysteresis observed at the single particle level is following the normal/inverse hysteresis loops of the catalytic performances. This approach opens a powerful avenue for studying, at the single particle level, catalytic nanomaterials and deactivation processes under operando conditions that will enable profound insights into nanoscale catalytic mechanisms.

了解催化剂的应变动态行为对于开发具有成本效益、高效、稳定和持久的催化剂至关重要。在这里，我们通过相干 X 射线衍射成像揭示了在操作条件下催化 CO 氧化反应期间单个金纳米晶体的原位三维应变演化。我们报告了在纳米尺度上对各向异性应变动力学的直接观察，其中晶体取向相同的晶面在质量上受到应变的不同影响，导致优先活性位点的形成。有趣的是，我们以 attojoule 精度绘制的单个纳米粒子弹性能量景观取决于加热与冷却循环。在单个粒子水平上观察到的滞后现象遵循催化性能的正常/反向滞后回路。