论文标题
用有机光氧化剂的水氧化和氢进化：理论观点
Water Oxidation and Hydrogen Evolution with Organic Photooxidants: A Theoretical Perspective
论文作者
论文摘要
从这个角度来看，我们讨论了一种新型的水分裂情景，即在氢键键入的发色团 - 水复合物中通过有机光氧化剂对水分子的直接氧化。与基于半导体的水分分裂的既定情况相比，电子传输过程的距离从介质尺度降低到Ångstrøm量表，并且时间尺度从毫秒到femtseconds降低，从而抑制了竞争竞争损失过程。该概念通过己嗪-H2O复合物的计算研究来说明。该复合物的激发状态景观已通过从头算电子结构方法进行了表征，并且已经通过非绝热动力学模拟探索了质子耦合的电子转移动力学。赫普嗪发色团的一个独特特征是存在低洼且异常长的1ππ*状态，其中可以将大量光子能量存储在数百个纳米方面，并用于水分子的氧化。计算表明，可以通过化学替代系统地对己嗪发色团的吸收光谱和光化学功能进行系统量身定制。讨论了收集氢的选择以及OH自由基的高反应性带来的问题。
In this perspective, we discuss a novel water-splitting scenario, namely the direct oxidation of water molecules by organic photooxidants in hydrogen-bonded chromophore-water complexes. In comparison with the established scenario of semiconductor-based water splitting, the distance of electron transfer processes is thereby reduced from mesoscopic scales to the Ångstrøm scale and the time scale is reduced from milliseconds to femtoseconds, which suppresses competing loss processes. The concept is illustrated by computational studies for the heptazine-H2O complex. The excited-state landscape of this complex has been characterized with ab initio electronic-structure methods and the proton-coupled electron-transfer dynamics has been explored with nonadiabatic dynamics simulations. A unique feature of the heptazine chromophore is the existence of a low-lying and exceptionally long-lived 1ππ* state in which a substantial part of the photon energy can be stored for hundreds of nanoseconds and is available for the oxidation of water molecules. The calculations reveal that the absorption spectra and the photochemical functionalities of heptazine chromophores can be systematically tailored by chemical substitution. The options of harvesting hydrogen and the problems posed by the high reactivity of OH radicals are discussed.
