Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States.
J Am Chem Soc. 2013 Dec 18;135(50):18774-7. doi: 10.1021/ja410685m. Epub 2013 Dec 10.
Titanium dioxide (TiO2) is a prototype, water-splitting (photo)catalyst, but its performance is limited by the large overpotential for the oxygen evolution reaction (OER). We report here a first-principles density functional theory study of the chemical dynamics of the first proton-coupled electron transfer (PCET), which is considered responsible for the large OER overpotential on TiO2. We use a periodic model of the TiO2/water interface that includes a slab of anatase TiO2 and explicit water molecules, sample the solvent configurations by first principles molecular dynamics, and determine the energy profiles of the two electronic states involved in the electron transfer (ET) by hybrid functional calculations. Our results suggest that the first PCET is sequential, with the ET following the proton transfer. The ET occurs via an inner sphere process, which is facilitated by a state in which one electronic hole is shared by the two oxygen ions involved in the transfer.
二氧化钛 (TiO2) 是一种水分解 (光) 催化剂的原型，但它的性能受到析氧反应 (OER) 过电位大的限制。我们在此报告了对第一质子耦合电子转移 (PCET) 的化学动力学的第一性原理密度泛函理论研究，该 PCET 被认为是 TiO2 上大的 OER 过电位的原因。我们使用包括锐钛矿 TiO2 薄片和显式水分子的 TiO2/水界面的周期性模型，通过第一性原理分子动力学对溶剂构型进行采样，并通过混合泛函计算确定电子转移 (ET) 中涉及的两个电子态的能量曲线。我们的结果表明，第一个 PCET 是顺序发生的，电子转移紧随质子转移之后。ET 通过内球过程发生，该过程由一个电子空穴被参与转移的两个氧离子共享的状态促进。
