Chu Weibin, Zheng Qijing, Prezhdo Oleg V, Zhao Jin
ICQD/Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China.
Department of Chemistry and Department of Physics and Astronomy , University of Southern California , Los Angeles , California 90089 , United States.
J Am Chem Soc. 2020 Feb 12;142(6):3214-3221. doi: 10.1021/jacs.9b13280. Epub 2020 Jan 30.
The most critical bottleneck in CO photoreduction lies in the activation of CO to form an anion radical, CO, or other intermediates by the photoexcited electrons, because CO has a high-energy lowest unoccupied molecular orbital (LUMO). Taking rutile TiO(110) as a prototypical surface, we use time-dependent nonadiabatic molecular dynamics simulations to reveal that the excitation of bending and antisymmetric stretching vibrations of CO can sufficiently stabilize the CO LUMO below the conduction band minimum, allowing it to trap photoexcited hot electrons and get reduced. Such vibrational excitations occur by formation of a transient CO adsorbed in an oxygen vacancy. CO can trap the hot electrons for nearly 100 fs and dissociate to form CO within 30-40 fs after the trapping. We propose that the activation of the CO bending and antisymmetric stretching vibrations driven by hot electrons applies to other CO reduction photocatalysts and can be realized by different techniques and material design.
CO光还原过程中最关键的瓶颈在于通过光激发电子将CO激活以形成阴离子自由基、CO或其他中间体，因为CO具有高能的最低未占据分子轨道（LUMO）。以金红石TiO(110)作为典型表面，我们采用含时非绝热分子动力学模拟来揭示，CO弯曲振动和反对称伸缩振动的激发能够充分将CO的LUMO稳定在导带最小值以下，使其能够捕获光激发的热电子并被还原。这种振动激发通过形成吸附在氧空位中的瞬态CO而发生。CO能够捕获热电子近100飞秒，并在捕获后30 - 40飞秒内解离形成CO。我们提出，由热电子驱动的CO弯曲振动和反对称伸缩振动的激活适用于其他CO还原光催化剂，并且可以通过不同的技术和材料设计来实现。
