稀土倍半氧化物表面上无势垒水分解的第一性原理研究
Barrierless Water Dissociation on Rare-Earth Sesquioxide Surfaces from First Principles
查看机构详情
- Idaho National Laboratory（爱达荷国家实验室）
- University of Notre Dame（圣母大学）
机构由 AI 辅助整理，请以论文原文为准。
浏览论文内容
中文总结 AI 辅助
本研究通过第一性原理分子动力学结合机器学习力场，发现稀土倍半氧化物表面存在无势垒的远端水分解路径，归因于固有欠配位位点。
中文摘要 AI 辅助
金属氧化物表面上的水分解是多相催化、光催化和辐射化学中的一个关键基元步骤，然而其在稀土（RE）倍半氧化物上的机理细节仍知之甚少。在此，我们利用结合从头计算与实时机器学习力场加速的分子动力学方法，研究了三种立方方铁锰矿型氧化物Sc$_2$O$_3$、Y$_2$O$_3$和Lu$_2$O$_3$的(110)表面上的水分解过程。通过对每种材料采样25条独立轨迹，我们获得了传统静态计算无法触及的反应景观的无偏图像。我们识别出两种不同的解离路径：一种传统的近端机制，具有约0.1 eV的小但有限的势垒；以及一种先前未报道的远端机制，该机制实际上是无势垒的，并且在吸附和解离阶段均在能量上更有利。低势垒与方铁锰矿晶格中周期性排列的固有欠配位RE$^{3+}$位点一致，表明有序的内在配位缺陷所起的作用类似于传统氧化物中随机氧空位的作用。
英文摘要
Water dissociation on metal oxide surfaces is a key elementary step in heterogeneous catalysis, photocatalysis, and radiation chemistry, yet its mechanistic details on rare-earth (RE) sesquioxides remain poorly understood. Here, we investigate water dissociation on the (110) surfaces of three cubic bixbyite oxides, Sc$_2$O$_3$, Y$_2$O$_3$, and Lu$_2$O$_3$, using molecular dynamics combining ab initio calculations with on-the-fly machine-learning force field acceleration. By sampling 25 independent trajectories per material, we obtain an unbiased picture of the reaction landscape inaccessible to conventional static calculations. Two distinct dissociation pathways are identified: a conventional proximal mechanism with a small but finite barrier of $\sim$0.1 eV, and a previously unreported distal mechanism that is effectively barrierless and energetically preferred at both the adsorption and dissociation stages. The low barriers are consistent with the periodic array of inherently undercoordinated RE$^{3+}$ sites in the bixbyite lattice, suggesting that ordered intrinsic coordination defects play a role analogous to stochastic oxygen vacancies in conventional oxides.
