Senftle Thomas P, Lessio Martina, Carter Emily A
Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544-5263, United States.
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
ACS Cent Sci. 2017 Sep 27;3(9):968-974. doi: 10.1021/acscentsci.7b00233. Epub 2017 Aug 25.
We propose a general reaction mechanism for the pyridine (Py)-catalyzed reduction of CO over GaP(111), CdTe(111), and CuInS(112) photoelectrode surfaces. This mechanism proceeds via formation of a surface-bound dihydropyridine (DHP) analogue, which is a newly postulated intermediate in the Py-catalyzed mechanism. Using density functional theory, we calculate the standard reduction potential related to the formation of the DHP analogue, which demonstrates that it is thermodynamically feasible to form this intermediate on all three investigated electrode surfaces under photoelectrochemical conditions. Hydride transfer barriers from the intermediate to CO demonstrate that the surface-bound DHP analogue is as effective at reducing CO to HCOO as the DHP molecule in solution. This intermediate is predicted to be both stable and active on many varying electrodes, therefore pointing to a mechanism that can be generalized across a variety of semiconductor surfaces, and explains the observed electrode dependence of the photocatalysis. Design principles that emerge are also outlined.
我们提出了一种用于吡啶（Py）催化在GaP(111)、CdTe(111)和CuInS(112)光电极表面还原CO的通用反应机理。该机理通过形成表面结合的二氢吡啶（DHP）类似物进行，这是Py催化机理中一个新提出的中间体。利用密度泛函理论，我们计算了与DHP类似物形成相关的标准还原电位，这表明在光电化学条件下，在所有三个研究的电极表面上形成这种中间体在热力学上是可行的。从中间体到CO的氢化物转移势垒表明，表面结合的DHP类似物在将CO还原为HCOO方面与溶液中的DHP分子一样有效。预计该中间体在许多不同的电极上既稳定又活跃，因此指出了一种可以推广到各种半导体表面的机理，并解释了观察到的光催化对电极的依赖性。还概述了由此产生的设计原则。
