Journal
ACS ENERGY LETTERS
Volume 7, Issue 12, Pages 4224-4231Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsenergylett.2c02292
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Funding
- National Natural Science Foundation of China [U2002213, 52161160331, 22179088]
- Science and Technology Development Fund Macau SAR [0077/2021/A2]
- Natural Science Foundation of Jiangsu Province of China [BK20220027, BK20210699]
- Program for Jiangsu Specially-Appointed Professors
- Collaborative Innovation Center of Suzhou Nano Science and Technology
- 111 Project
- Joint International Research Laboratory of Carbon-Based Functional Materials and Devices
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In this study, an acid-fed membrane electrode assembly (MEA) for CO2 electroreduction was demonstrated, achieving high CO Faradaic efficiencies and activities under acidic conditions. The balance between H+ and Cs+ concentrations was found to play a significant role in determining the selectivity and activity. Additionally, the acid-fed MEA exhibited a remarkable long-term stability.
The formation of (bi)carbonates is a pressing issue for CO2 electroreduction in neutral or alkaline solutions. It adversely causes low single-pass conversion efficiency as a result of (bi)carbonate crossover, as well as limited device lifetimes as a result of (bi)carbonate precipitation at the cathode. One emerging solution to circumvent this challenge is conducting the reaction in acids. To this end, we here demonstrate an acid-fed membrane electrode assembly (MEA) for CO2 electroreduction to CO. A diluted electrolyte with an H+ to Cs+ ratio of 1:1 and a relatively low current density are optimal conditions to achieve high CO Faradaic efficiencies. A relatively high H+ versus Cs+ ratio offers high electrocatalytic activities. By systematically evaluating the impact of H+ and Cs+ concentration on the electrochemical performance, we uncover the essential role of the balance between the rates of (bi)carbonate formation and H+ diffusion in determining the selectivity and activity. As a result, we report a CO partial current density of similar to 105 mA cm(-2) at an similar to 4 V cell voltage, a near-doubled activity toward CO compared to a neutral MEA at a similar voltage. Under the optimal conditions for long-term operation, our acid-fed membrane electrode assembly is capable of delivering a CO Faradaic efficiency of similar to 80%, an extraordinary single-pass conversion efficiency of similar to 90% (about twice that of neutral MEA), and a 50 h long-term stability notably superior to those in previous reports.
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