Unraveling the rate-limiting step of two-electron transfer electrochemical reduction of carbon dioxide.
Unraveling the rate-limiting step of two-electron transfer electrochemical reduction of carbon dioxide.
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解开二氧化碳双电子转移电化学还原的限速步骤
DOI：
10.1038/s41467-022-28436-z
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发表时间：
2022-02-10
影响因子：
16.6
通讯作者：
Gong J
中科院分区：
文献类型：
--
作者：
Deng W;Zhang P;Seger B;Gong J
二氧化碳的电化学还原(CO2ER)因其具有可持续生产有价值的燃料和化学品的潜力而受到广泛关注。然而，其反应机理仍不是很清楚。一个关键的争论是，限速步骤(RLS)是由质子的可用性、水分子的转化还是二氧化碳的吸附决定的。本文通过研究pH依赖性和动力学同位素效应对CO2ER速率表达的影响，描述了对RLS模型的洞察。针对两电子转移反应的电催化剂，我们发现在Au、Ag、Sn和In上，CO和甲酸盐的生成速率不随电解液的pH值或氢化程度而变化。我们解释了双电子转移CO_2ER的RLS是CO_2在电催化剂表面的吸附。我们希望这一发现将为提高CO2ER的活性提供指导，通过对催化剂进行表面修饰以及仔细控制反应器内的压力和界面电场等策略来增强CO2的吸附过程。CO_2的电还原研究很多，但其反应机理还有待进一步探讨。在这里，作者研究了与二氧化碳电还原速率表达有关的pH依赖性和动力学同位素效应，以进一步了解限速步骤。
Electrochemical reduction of CO2 (CO2ER) has received significant attention due to its potential to sustainably produce valuable fuels and chemicals. However, the reaction mechanism is still not well understood. One vital debate is whether the rate-limiting step (RLS) is dominated by the availability of protons, the conversion of water molecules, or the adsorption of CO2. This paper describes insights into the RLS by investigating pH dependency and kinetic isotope effect with respect to the rate expression of CO2ER. Focusing on electrocatalysts geared towards two-electron transfer reactions, we find the generation rates of CO and formate to be invariant with either pH or deuteration of the electrolyte over Au, Ag, Sn, and In. We elucidate the RLS of two-electron transfer CO2ER to be the adsorption of CO2 onto the surface of electrocatalysts. We expect this finding to provide guidance for improving CO2ER activity through the enhancement of the CO2 adsorption processes by strategies such as surface modification of catalysts as well as careful control of pressure and interfacial electric field within reactors. Electroreduction of CO2 is heavily investigated but its reaction mechanism needs to be further explored. Here, the authors investigate pH dependency and kinetic isotope effect with respect to the rate expression of CO2 electroreduction to gain further insights into the rate-limiting step.
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