Probing the Reaction Mechanism of CO2 Electroreduction over Ag Films via Operando Infrared Spectroscopy
Probing the Reaction Mechanism of CO2 Electroreduction over Ag Films via Operando Infrared Spectroscopy
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DOI：
10.1021/acscatal.6b02382
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发表时间：
2017-01-01
期刊：
影响因子：
12.9
通讯作者：
Smith, Wilson A.
中科院分区：
文献类型：
--
作者：
Firet, Nienke J.;Smith, Wilson A.
近年来，电催化还原CO2为化学燃料引起了极大的关注。在过渡金属中，银显示出作为主要反应产物的CO形成的最高法拉第效率之一;然而，这种转化的确切机制尚未完全理解。本文利用原位衰减全反射傅里叶变换红外光谱（ATR-FTIR）研究了银作为CO2还原催化剂在电化学循环过程中的反应机理。使用ATR-FTIR，可以观察到在CO2电还原反应过程中形成的Ag薄膜表面的反应中间体。在中等过电位下，质子耦合电子转移反应机制被证实是主要的CO2还原途径。然而，在一个更负的应用电位，COO-和COOH的中间体检测使用ATR-FTIR，这表明，个别质子和电子转移步骤发生，提供了一个不同的途径比在较低的电位。这些结果表明，CO2还原反应机制可能是潜在的依赖性，并不总是涉及一个协调的质子耦合电子转移，打开替代途径，以优化有效的和选择性的催化剂所需的产品形成。
The electrocatalytic reduction of CO2 to chemical fuels has attracted significant attention in recent years. Among transition metals, silver shows one of the highest faradaic efficiencies for CO formation as the main reaction product; however, the exact mechanism for this conversion is not fully understood. In this work, we study the reaction mechanism of silver as a CO2 reduction catalyst using in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) during electrochemical cycling. Using ATR-FTIR, it is possible to observe the reaction intermediates on the surface of Ag thin films formed during the CO2 electroreduction reaction. At a moderate overpotential, a proton coupled electron transfer reaction mechanism is confirmed to be the dominant CO2 reduction pathway. However, at a more negative applied potential, both the COO- and the COOH intermediates are detected using ATR-FTIR, which indicates that individual proton and electron transfer steps occur, offering a different pathway than at lower potentials. These results indicate that the CO2 reduction reaction mechanism can be potential dependent and not always involving a concerted proton coupled electron transfer, opening alternative pathways to optimize efficient and selective catalysts for desired product formation.