Effect of Electrolyte Composition and Concentration on Pulsed Potential Electrochemical CO2 Reduction
Effect of Electrolyte Composition and Concentration on Pulsed Potential Electrochemical CO2 Reduction
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DOI：
10.1002/celc.202001445
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发表时间：
2021-01-25
期刊：
影响因子：
4
通讯作者：
Hanrath, Tobias
中科院分区：
文献类型：
--
作者：
Casebolt, Rileigh;Kimura, Kevin W.;Hanrath, Tobias
随着CO2排放量的增加和人们对CO2价值的关注，电化学CO2还原（eCO（2）R）技术在碳回收和化学储能方面具有广阔的前景。然而，产品选择性和电催化剂寿命仍然是广泛实施eCO（2）R的障碍。改善这一挑战的一种可能的解决方案是脉冲施加的电势。然而，目前尚不清楚从更传统的恒定电位eCO（2）R获得的趋势和经验教训是否以及如何转化为脉冲电位eCO（2）R。在本工作中，我们报道了脉冲电位eCO（2）R与恒电位eCO（2）R的电解质浓度/组成与产物分布之间的关系。在恒电位eCO（2）R的情况下，增加KHCO 3浓度有利于H2-和CH 4的生成。相比之下，对于脉冲电位eCO（2）R，由于表面质子的周期性解吸，H-2的形成被抑制，而CH 4仍然是有利的。在KCl的情况下，在恒定电位eCO（2）R期间增加浓度不影响产物分布，主要产生H-2和CO。然而，在脉冲电位eCO（2）R期间增加KCl浓度持续抑制H-2形成并极大地有利于C-2产物，达到71%法拉第效率。总的来说，这些结果提供了新的机制的见解脉冲eCO（2）R机制的质子供体能力和离子电导率的背景下。
With rising CO2 emissions and growing interests towards CO2 valorization, electrochemical CO2 reduction (eCO(2)R) has emerged as a promising prospect for carbon recycling and chemical energy storage. Yet, product selectivity and electrocatalyst longevity persist as obstacles to the broad implementation of eCO(2)R. A possible solution to ameliorate this challenge is to pulse the applied potential. However, it is currently unclear whether and how the trends and lessons obtained from the more conventional constant potential eCO(2)R translate to pulsed potential eCO(2)R. In this work, we report that the relationship between electrolyte concentration/composition and product distribution for pulsed potential eCO(2)R is different from constant potential eCO(2)R. In the case of constant potential eCO(2)R, increasing KHCO3 concentration favors the formation of H-2 and CH4. In contrast, for pulsed potential eCO(2)R, H-2 formation is suppressed due to the periodic desorption of surface protons, while CH4 is still favored. In the case of KCl, increasing the concentration during constant potential eCO(2)R does not affect product distribution, mainly producing H-2 and CO. However, increasing KCl concentration during pulsed potential eCO(2)R persistently suppresses H-2 formation and greatly favors C-2 products, reaching 71 % Faradaic efficiency. Collectively, these results provide new mechanistic insights into the pulsed eCO(2)R mechanism within the context of proton-donator ability and ionic conductivity.