Department of Chemistry, University of Rochester, Rochester, New York 14627, United States.
J Am Chem Soc. 2022 Mar 23;144(11):5029-5041. doi: 10.1021/jacs.1c13432. Epub 2022 Mar 11.
The uptake of hydrogen atoms (H-atoms) into reducible metal oxides has implications in catalysis and energy storage. However, outside of computational modeling, it is difficult to obtain insight into the physicochemical factors that govern H-atom uptake at the atomic level. Here, we describe oxygen-atom vacancy formation in a series of hexavanadate assemblies via proton-coupled electron transfer, presenting a novel pathway for the formation of defect sites at the surface of redox-active metal oxides. Kinetic investigations reveal that H-atom transfer to the metal oxide surface occurs through concerted proton-electron transfer, resulting in the formation of a transient V-OH moiety that, upon displacement of the water ligand with an acetonitrile molecule, forms the oxygen-deficient polyoxovanadate-alkoxide cluster. Oxidation state distribution of the cluster core dictates the affinity of surface oxido ligands for H-atoms, mirroring the behavior of reducible metal oxide nanocrystals. Ultimately, atomistic insights from this work provide new design criteria for predictive proton-coupled electron-transfer reactivity of terminal M═O moieties at the surface of nanoscopic metal oxides.
氢原子（H-atoms）在可还原金属氧化物中的吸收在催化和储能方面具有重要意义。然而，除了计算模型之外，很难深入了解原子水平上控制 H 原子吸收的物理化学因素。在这里，我们通过质子耦合电子转移描述了一系列六钒酸盐组装体中氧原子空位的形成，为氧化还原活性金属氧化物表面缺陷位点的形成提供了一种新途径。动力学研究表明，H 原子通过协同质子-电子转移转移到金属氧化物表面，形成瞬态 V-OH 部分，当水配体被乙腈分子取代时，形成缺氧多钒酸盐-烷氧基簇。簇核的氧化态分布决定了表面氧代配体对 H 原子的亲和力，反映了可还原金属氧化物纳米晶体的行为。最终，这项工作的原子见解为纳米尺度金属氧化物表面末端 M═O 部分的预测质子耦合电子转移反应性提供了新的设计标准。
