Visible-Light Photoredox Catalysis: Selective Reduction of Carbon Dioxide to Carbon Monoxide by a Nickel N-Heterocyclic Carbene-Isoquinoline Complex
Visible-Light Photoredox Catalysis: Selective Reduction of Carbon Dioxide to Carbon Monoxide by a Nickel N-Heterocyclic Carbene-Isoquinoline Complex
复制标题
DOI：
10.1021/ja4074003
复制
发表时间：
2013-09-25
影响因子：
15
通讯作者：
Chang, Christopher J.
中科院分区：
文献类型：
--
作者：
Thoi, V. Sara;Kornienko, Nikolay;Chang, Christopher J.
利用太阳能将二氧化碳还原为具有附加值的化学燃料是催化、能源科学和绿色化学领域的一个长期挑战。为了开发有效的CO2固定，必须平衡几个关键考虑因素，包括（1）促进CO2还原的催化剂选择性超过质子还原的竞争性氢气生成，（2）与太阳光谱匹配的可见光收集，以及（3）使用廉价和地球丰富的催化组分。本文报道了一类新的以N-杂环卡宾胺为配体的稀土镍配合物的合成和表征，该配合物对CO2的电催化和光催化转化具有高的选择性和活性。研究了配体中卡宾和胺给体的系统变化，[Ni（（Pr）bimiq 1）]（2+）（1c，其中（Pr）bimiq 1 =双（3-（咪唑基）异喹啉基）丙烷）作为具有最低阴极起始电位（E-cat = -1.2 V vs SCE）的CO2电化学还原催化剂出现。利用这种地球资源丰富的催化剂与Ir（ppy）（3）（其中ppy = 2-苯基吡啶）和电子供体，我们开发了一种用于催化转化CO2为CO的可见光光氧化还原体系，该体系具有高选择性和活性，并且实现了分别达到98，000和3.9 s（-1）的转换数和转换频率。进一步的研究表明，这种太阳能-燃料循环的整体效率可能受到活性镍催化剂的形成和/或在还原镍中心将CO2化学还原为CO的限制，并为改进光氧化还原系统以实现可持续的碳中性能量转换提供了起点。
The solar-driven reduction of carbon dioxide to value-added chemical fuels is a longstanding challenge in the fields of catalysis, energy science, and green chemistry. In order to develop effective CO2 fixation, several key considerations must be balanced, including (1) catalyst selectivity for promoting CO2 reduction over competing hydrogen generation from proton reduction, (2) visible-light harvesting that matches the solar spectrum, and (3) the use of cheap and earth-abundant catalytic components. In this report, we present the synthesis and characterization of a new family of earth-abundant nickel complexes supported by N-heterocyclic carbene-amine ligands that exhibit high selectivity and activity for the electrocatalytic and photocatalytic conversion of CO2 to CO. Systematic changes in the carbene and amine donors of the ligand have been surveyed, and [Ni((Pr)bimiq1)](2+) (1c, where (Pr)bimiq1 = bis(3-(imidazolyl)isoquinolinyl)propane) emerges as a catalyst for electrochemical reduction of CO2 with the lowest cathodic onset potential (E-cat = -1.2 V vs SCE). Using this earth-abundant catalyst with Ir(ppy)(3) (where ppy = 2-phenylpyridine) and an electron donor, we have developed a visible-light photoredox system for the catalytic conversion of CO2 to CO that proceeds with high selectivity and activity and achieves turnover numbers and turnover frequencies reaching 98,000 and 3.9 s(-1), respectively. Further studies reveal that the overall efficiency of this solar-to-fuel cycle may be limited by the formation of the active Ni catalyst and/or the chemical reduction of CO2 to CO at the reduced nickel center and provide a starting point for improved photoredox systems for sustainable carbon-neutral energy conversion.