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Inhibiting Hydrogen Evolution using a Chloride Adlayer for Efficient Electrochemical CO2 Reduction on Zn Electrodes
Meiming Zhao1, Huang Tang1, Qimeng Yang1
1Jiangsu Key Laboratory of Artificial Functional Materials, Eco-materials and Renewable Energy Research Center (ERERC), National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, College of Engineering and Applied Sciences , Nanjing University , No. 22 Hankou Road , Nanjing , Jiangsu 210093 , P. R. China.
ACS Applied Materials & Interfaces
|January 8, 2020
Summary
Adding chloride ions to zinc electrodes for electrochemical carbon dioxide reduction significantly boosts CO production by blocking hydrogen evolution. This enhances electron transfer, improving efficiency for sustainable chemical synthesis.
Area of Science:
- Electrochemistry
- Materials Science
- Catalysis
Background:
- Electrochemical reduction of carbon dioxide (CO2) is crucial for sustainable energy and chemical production.
- A major challenge is suppressing the competing hydrogen evolution reaction (HER).
Purpose of the Study:
- To investigate the impact of specifically adsorbed chloride ions (Cl-) on HER during CO2 reduction using a bulk zinc (Zn) electrode.
- To elucidate the mechanism by which chloride ions influence CO2 electroreduction.
Main Methods:
- Electrochemical experiments using a bulk Zn electrode in electrolytes with and without chloride ions.
- Analysis of the electrode surface and reaction products to understand the role of chloride.
Main Results:
- Formation of a Zn-Cl adlayer due to direct chemical bonding between weakly solvated Cl- and Zn.
- The Zn-Cl adlayer effectively suppressed HER.
- Facilitated electron transfer to CO2 via Cl, stabilizing the CO2- radical.
- A fourfold increase in CO Faradaic efficiency for CO2 reduction in KCl electrolyte compared to KHCO3 at -1.2 V vs. RHE.
Conclusions:
- Specifically adsorbed chloride ions can selectively inhibit HER on Zn electrodes.
- The Zn-Cl adlayer promotes CO2 reduction to CO by enhancing electron transfer and stabilizing key intermediates.
- Chloride ion addition offers a promising strategy to improve the efficiency of electrochemical CO2 reduction.
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