Domino electroreduction of CO2 to methanol on a molecular catalyst
Domino electroreduction of CO2 to methanol on a molecular catalyst
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DOI：
10.1038/s41586-019-1760-8
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发表时间：
2019-11-28
期刊：
影响因子：
64.8
通讯作者：
Wang, Hailiang
中科院分区：
文献类型：
--
作者：
Wu, Yueshen;Jiang, Zhan;Wang, Hailiang
电化学二氧化碳(CO2)减排原则上可以利用可再生能源将碳排放转化为燃料和增值化学品，如碳氢化合物和醇，但该过程的效率受到其缓慢动力学的限制(1，2)。分子催化剂具有明确的活性中心和精确可裁剪的结构，允许基于机理的性能优化，过渡金属配合物在这方面已经得到了广泛的探索。然而，这些催化剂通常缺乏在两电子过程之外促进二氧化碳还原以产生更有价值的产品的能力(1，3)。在这里，我们展示了当固定在碳纳米管上时，以前用于将二氧化碳还原为主要是CO催化的六电子二氧化碳还原为甲醇的酞菁钴具有相当的活性和选择性。我们发现，在近中性电解液中，通过一个独特的多米诺骨牌过程进行转化，生成的甲醇相对于可逆氢电极在近中性电解液中具有高于40%的法拉第效率和大于每平方厘米10毫安的部分电流密度。催化剂的催化活性随着时间的推移而降低，这是由于酞菁配体的有害还原，这可以通过在酞菁环上添加给电子的氨基取代来抑制。改进的分子基电催化剂将二氧化碳转化为甲醇，具有相当高的活性和选择性，并且至少在12小时内具有稳定的性能。
Electrochemical carbon dioxide (CO2) reduction can in principle convert carbon emissions to fuels and value-added chemicals, such as hydrocarbons and alcohols, using renewable energy, but the efficiency of the process is limited by its sluggish kinetics(1,2). Molecular catalysts have well defined active sites and accurately tailorable structures that allow mechanism-based performance optimization, and transition-metal complexes have been extensively explored in this regard. However, these catalysts generally lack the ability to promote CO2 reduction beyond the two-electron process to generate more valuable products(1,3). Here we show that when immobilized on carbon nanotubes, cobalt phthalocyanine-used previously to reduce CO2 to primarily CO-catalyses the six-electron reduction of CO2 to methanol with appreciable activity and selectivity. We find that the conversion, which proceeds via a distinct domino process with CO as an intermediate, generates methanol with a Faradaic efficiency higher than 40 per cent and a partial current density greater than 10 milliamperes per square centimetre at -0.94 volts with respect to the reversible hydrogen electrode in a near-neutral electrolyte. The catalytic activity decreases over time owing to the detrimental reduction of the phthalocyanine ligand, which can be suppressed by appending electron-donating amino substituents to the phthalocyanine ring. The improved molecule-based electrocatalyst converts CO2 to methanol with considerable activity and selectivity and with stable performance over at least 12 hours.