Transmission Mode 2D-IR Spectroelectrochemistry of In Situ Electrocatalytic Intermediates
Transmission Mode 2D-IR Spectroelectrochemistry of In Situ Electrocatalytic Intermediates
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DOI：
10.1021/acs.jpclett.1c00504
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发表时间：
2021-04-09
影响因子：
5.7
通讯作者：
Kubarych, Kevin J.
中科院分区：
文献类型：
--
作者：
Kiefer, Laura M.;Michocki, Lindsay B.;Kubarych, Kevin J.
解开电催化机理，以及中间体的基本结构动力学，需要具有高时间和频率分辨率的光谱，能够解释电化学固有的非平衡原位浓度变化。二维红外光谱(2D-IR)是一种理想的候选方法，但一些技术挑战阻碍了这一强大的光谱电化学(SEC)工具的发展。我们展示了一种适用于2D-IR-SEC的透射式光学透明薄层电化学(OTTLE)池，用于监测重要的Re(Bpy)(CO)(3)ClCO2-还原电催化剂。2D-IR-SEC表明，单一还原催化剂[Re(Bpy)(CO)(3)Cl](中心圆点-)与起始催化剂Re(Bpy)(CO)(3)Cl在光谱扩散时间和光谱不均匀性方面均有显著差异。在电化学反应过程中，分辨良好的对称振动和拥挤的低频带之间的交叉峰可以直接指定所有不同的物种。有了这些信息，2D-IR-SEC提供了关于非生产性、催化剂降解的二聚反应的新的机械见解。2D-IR-SEC为未来能源转化和温室气体减排的电催化基础开辟了新的实验窗口。
Unraveling electrocatalytic mechanisms, as well as fundamental structural dynamics of intermediates, requires spectroscopy with high time and frequency resolution that can account for nonequilibrium in situ concentration changes inherent to electrochemistry. Two-dimensional infrared (2D-IR) spectroscopy is an ideal candidate, but several technical challenges have hindered development of this powerful tool for spectroelectrochemistry (SEC). We demonstrate a transmission-mode, optically transparent thin-layer electrochemical (OTTLE) cell adapted to 2D-IR-SEC to monitor the important Re(bpy)(CO)(3)Cl CO2-reduction electrocatalyst. 2D-IR-SEC reveals pronounced differences in both spectral diffusion time scales and spectral inhomogeneity in the singly reduced catalyst, [Re(bpy)(CO)(3)Cl](center dot-), relative to the starting Re(bpy)(CO)(3)Cl. Cross-peaks between well-resolved symmetric vibrations and congested low-frequency bands enable direct assignment of all distinct species during the electrochemical reaction. With this information, 2D-IR-SEC provides new mechanistic insights regarding unproductive, catalyst-degrading dimerization. 2D-IR-SEC opens new experimental windows into the electrocatalysis foundation of future energy conversion and greenhouse gas reduction.