Theoretical Insights into Electrochemical CO2 Reduction Mechanisms Catalyzed by Surface-Bound Nitrogen Heterocycles
Theoretical Insights into Electrochemical CO2 Reduction Mechanisms Catalyzed by Surface-Bound Nitrogen Heterocycles
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DOI：
10.1021/jz4021519
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发表时间：
2013-12-05
影响因子：
5.7
通讯作者：
Carter, Emily A.
中科院分区：
文献类型：
--
作者：
Keith, John A.;Carter, Emily A.
我们提出了一个新颖而通用的反应机理来解释氮杂环(光)促进的二氧化碳电化学还原反应的独特性能。这一机理是基于最近对吡啶催化的二氧化碳还原的计算和实验研究的观察结果。本文报道了用第一性原理量子化学计算得到的pK(A)、S和吸附在GaP光电极上物种的标准还原电势。我们发现，在间隙表面，质子还原或吡啶还原在能量上是不利的，即使在非常负的电极电位下。然而，在较小的负电位下，将表面结合的吡啶转化为2E(-)还原物种，如二氢吡啶，在热力学上是有利的。有趣的是，这些瞬时的2E(-)还原物种与一些生物氧化还原催化剂(如NADH)具有相似的化学成分，它们的还原电位与将二氧化碳转化为各种产物的热力学氧化还原电位相似。
We propose a novel and general reaction mechanism to explain the unique performance of nitrogen-heterocycle-promoted (photo)electrochemical CO2 reduction reactions. This mechanism is based on observations from recent computational and experimental studies of pyridinium-catalyzed CO2 reduction. Herein we report pK(a)s and standard reduction potentials of species adsorbed on GaP photoelectrodes derived from first-principles quantum chemistry computations. We show that on GaP surfaces, proton reduction or pyridinium reduction is energetically unfavorable even at very negative electrode potentials. However, it is thermodynamically favorable to convert a surface-bound pyridine into a 2e(-) reduced species such as dihydropyridine at less negative applied potentials. Intriguingly, these transient 2e(-) reduced species share a similar chemical moiety as some biological redox catalysts (e.g., NADH), and their reduction potentials are similar to the thermodynamic redox potentials that would convert CO2 to a variety of products.