Schwarzer Michael, Borodin Dmitriy, Wang Yingqi, Fingerhut Jan, Kitsopoulos Theofanis N, Auerbach Daniel J, Guo Hua, Wodtke Alec M
Institute for Physical Chemistry, University of Göttingen, 37077 Göttingen, Germany.
Department of Dynamics at Surfaces, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany.
Science. 2024 Nov;386(6721):511-516. doi: 10.1126/science.adk1334. Epub 2024 Oct 31.
Atomic-scale structures that account for the acceleration of reactivity by heterogeneous catalysts often form only under reaction conditions of high temperatures and pressures, making them impossible to observe with low-temperature, ultra-high-vacuum methods. We present velocity-resolved kinetics measurements for catalytic hydrogen oxidation on palladium over a wide range of surface concentrations and at high temperatures. The rates exhibit a complex dependence on oxygen coverage and step density, which can be quantitatively explained by a density functional and transition-state theory-based kinetic model involving a cooperatively stabilized configuration of at least three oxygen atoms at steps. Here, two oxygen atoms recruit a third oxygen atom to a nearby binding site to produce an active configuration that is far more reactive than isolated oxygen atoms. Thus, hydrogen oxidation on palladium provides a clear example of how reactivity can be enhanced on a working catalyst.
那些解释非均相催化剂如何加速反应活性的原子尺度结构通常仅在高温高压的反应条件下形成，这使得用低温、超高真空方法无法对其进行观测。我们展示了在广泛的表面浓度范围和高温下，钯上催化氢氧化反应的速度分辨动力学测量结果。反应速率对氧覆盖率和台阶密度呈现出复杂的依赖性，这可以通过基于密度泛函和过渡态理论的动力学模型进行定量解释，该模型涉及台阶处至少三个氧原子的协同稳定构型。在此，两个氧原子将第三个氧原子吸引到附近的结合位点，从而产生一种活性构型，其反应活性远高于孤立的氧原子。因此，钯上的氢氧化反应为工作催化剂上反应活性如何增强提供了一个清晰的例子。
