Mechanistic Insights into Catalyst-Assisted Nonaqueous Oxygen Evolution Reaction in Lithium–Oxygen Batteries

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• 作者：Yu Wang ; Zhuojian Liang ; Qingli Zou ; Guangtao Cong ; Yi-Chun Lu
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：March 31, 2016
• 年：2016
• 卷：120
• 期：12
• 页码：6459-6466
• 全文大小：510K
• ISSN：1932-7455

文摘

Rational catalyst design for oxygen evolution reaction (OER) in nonaqueous lithium–oxygen (Li–O₂) batteries has been hindered due to large discrepancies in the efficacy and working mechanism of solid catalysts in decomposing solid lithium peroxide (Li₂O₂). One school of thought reported pronounced catalyst influence on improving the oxidation kinetics of Li₂O₂. Many of them have attributed the enhancement to the presence of soluble species acting as mass-transport facilitators. Another school of thought reported that applying catalysts leads no improvement in the Li₂O₂ oxidation kinetics due to lacking of soluble species derived from Li₂O₂ oxidation. These discrepancies and open questions preclude rational design of efficient catalysts for nonaqueous OER. In this work, using online electrochemical mass spectrometry, we show that solid catalysts (e.g., ruthenium) effectively promote Li₂O₂ oxidation kinetics to evolve O₂ in a solid-state environment. This unambiguously demonstrates that nonaqueous OER is a catalytic-active process and that catalysts enhance the OER via solid–solid interaction between the catalyst and the discharge products instead of liquid phase mediations. Our findings highlight that the key governing factor for nonaqueous OER activity lies in catalyst’s ability to interact/stabilize the solid reaction intermediates. Our work provides direct evidence of solid–solid OER catalysis and insights into its underlying enhancement mechanism.