General Efficacy of Atomically Dispersed Pt Catalysts for the Chlorine Evolution Reaction: Potential-Dependent Switching of the Kinetics and Mechanism,ACS Catalysis

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General Efficacy of Atomically Dispersed Pt Catalysts for the Chlorine Evolution Reaction: Potential-Dependent Switching of the Kinetics and Mechanism
ACS Catalysis ( IF 11.3 ) Pub Date : 2021-09-17 , DOI: 10.1021/acscatal.1c03893
Taejung Lim ₁ , Jae Hyung Kim ₁ , Jinjong Kim ₂ , Du San Baek ₁ , Tae Joo Shin ₃ , Hu Young Jeong ₃ , Kug-Seung Lee ₄ , Kai S. Exner _{5,

6,

7} , Sang Hoon Joo ₂

Affiliation

The electrochemical chlorine evolution reaction (CER) is a key anodic reaction in the chlor-alkali process for Cl₂ production, on-site generation of ClO^–, and Cl₂-mediated electrosynthesis. Although Ru-based mixed metal oxides have long been used as CER catalysts, they suffer from a selectivity problem due to the competing oxygen evolution reaction. To overcome this shortcoming, we have developed a new CER catalyst composed of atomically dispersed Pt–N₄ sites on carbon nanotubes (Pt₁/CNT). In this study, we demonstrate that the catalytically active Pt–N₄ sites can be constructed from H₂PtCl₆·6H₂O and an ionic liquid via a bottom-up approach and a Pt-porphyrin-driven top-down method. Both catalysts exhibit excellent CER activity and remarkable selectivity, demonstrating the general efficacy of Pt₁/CNT for the CER. The electrochemical and in situ X-ray absorption spectroscopy analyses reveal that Pt₁/CNT catalysts show a reaction order of ∼1.8 in the low overpotential regime, where the Volmer step is reconciled with the rate-determining step (RDS). Interestingly, in the high overpotential region, the CER over Pt₁/CNT proceeds with a lower reaction order and the RDS switches to the Heyrovský step. These unprecedented kinetic insights are clearly distinguished from the oxide-based CER catalysts with the opposite sequence of the RDS.

中文翻译：

用于氯演化反应的原子分散 Pt 催化剂的一般功效：动力学和机制的电位相关转换

电化学析氯反应 (CER) 是氯碱工艺中用于生产Cl ₂、现场生成 ClO ^–和 Cl ₂介导的电合成的关键阳极反应。尽管基于 Ru 的混合金属氧化物长期以来一直被用作 CER 催化剂，但由于竞争性析氧反应，它们存在选择性问题。为了克服这个缺点，我们开发了一种新的 CER 催化剂，它由碳纳米管上原子分散的 Pt-N ₄位点（Pt ₁ /CNT）组成。在这项研究中，我们证明了催化活性 Pt-N ₄位点可以由 H ₂ PtCl ₆ ·6H ₂构建O 和离子液体通过自下而上的方法和 Pt-卟啉驱动的自上而下的方法。两种催化剂都表现出优异的 CER 活性和显着的选择性，证明了 Pt ₁ /CNT 对 CER的一般功效。电化学和原位 X 射线吸收光谱分析表明，Pt ₁ /CNT 催化剂在低过电位状态下显示出约 1.8 的反应级数，其中 Volmer 步骤与速率决定步骤（RDS）相协调。有趣的是，在高过电位区域，Pt ₁ /CNT 上的 CER以较低的反应顺序进行，RDS 切换到 Heyrovský 步骤。这些前所未有的动力学见解与具有相反顺序的 RDS 的氧化物基 CER 催化剂明显不同。

更新日期：2021-10-01

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