催化学报 ›› 2023, Vol. 52: 14-31.DOI: 10.1016/S1872-2067(23)64511-5

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酸性条件下二氧化碳高效电还原策略

邹心仪, 顾均*()   

  1. 南方科技大学化学系, 广东深圳 518055
  • 收稿日期:2023-07-11 接受日期:2023-08-28 出版日期:2023-09-18 发布日期:2023-09-25
  • 通讯作者: *电子信箱: guj6@sustech.edu.cn (顾均).
  • 基金资助:
    国家自然科学基金(22272073);深圳市科技计划资助(JCYJ20210324104414039);深圳市科技计划资助(JCYJ20220818100410023);深圳市科技计划资助(KCXST20221021111207017);广东省基金(2021ZT09C064);广东基础与应用基础研究基金(2021A1515110360);广东基础与应用基础研究基金(2022A1515011976)

Strategies for efficient CO2 electroreduction in acidic conditions

Xinyi Zou, Jun Gu*()   

  1. Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
  • Received:2023-07-11 Accepted:2023-08-28 Online:2023-09-18 Published:2023-09-25
  • Contact: *E-mail: guj6@sustech.edu.cn (J. Gu).
  • About author:Jun Gu (Southern University of Science and Technology) received his B.S. degree in 2011 and Ph.D. degree in 2016 from Peking University. His doctoral thesis is about the synthesis and the catalytic applications of rare earth- and noble metal-based nanomaterials. At the end of 2016, he joined Lab of Inorganic Synthesis and Catalysis at École Polytechnique Fédérale de Lausanne (Switzerland) as a postdoctor. His research was focused on non-noble metal-based catalysts for CO2 electroreduction. At the beginning of 2021, he joined Department of Chemistry of Southern University of Science and Technology. Now he is an associate professor and the principal investigator of the group of electrocatalysis. His research interests mainly focus on catalyst designing and mechanism study for electrocatalytic activation of small molecules.
  • Supported by:
    National Natural Science Foundation of China(22272073);Shenzhen Science and Technology Program(JCYJ20210324104414039);Shenzhen Science and Technology Program(JCYJ20220818100410023);Shenzhen Science and Technology Program(KCXST20221021111207017);Guangdong Grants(2021ZT09C064);Guangdong Basic and Applied Basic Research Foundation(2021A1515110360);Guangdong Basic and Applied Basic Research Foundation(2022A1515011976)

摘要:

二氧化碳电还原技术可以将可再生电能与温室气体二氧化碳转化为高价值燃料和化学品. 选择性、能量转化效率、碳利用效率和可持续性是评价二氧化碳电还原技术是否具有工业应用前景的主要指标. 在碱性或中性电解液中进行二氧化碳电还原, 由于部分二氧化碳在阴极转化为碳酸盐, 导致碳利用效率降低. 碱性电解液和中性电解液还分别存在电解液再生过程耗能巨大和溶液电阻较高等问题. 这些因素导致使用碱性和中性电解液的二氧化碳电还原技术能量转化效率低下. 最近, 酸性条件下二氧化碳电还原技术有望提高碳利用效率和能量利用效率, 成为研究热点. 然而, 在酸性条件下提升二氧化碳还原选择性具有挑战. 前期研究已发展了多种策略以抑制酸性条件下的氢离子还原反应并促进二氧化碳还原反应, 但研究者对于酸性条件下的阳离子效应以及局域pH效应等基础科学问题认识尚不一致. 此外, 气体扩散电极内的碳酸氢盐盐析问题仍限制着酸性条件下二氧化碳还原电解系统的可持续性. 因此, 亟需对促进酸性条件下二氧化碳电还原的不同策略及可能机制进行总结, 并探讨进一步提升电解系统可持续性的潜在路径.

本文首先概述了酸性条件下二氧化碳电还原技术的提出及发展历程, 对比了碱性、中性和酸性电解液中进行二氧化碳电还原的优势和劣势. 着重从传质过程和电极反应两方面对已报道的酸性条件下二氧化碳电还原技术进行归纳总结. 探讨了传质过程中二氧化碳还原半反应引起的局域高pH对氢离子还原反应的抑制作用, 碱金属离子对于氢离子电迁移过程的抑制作用, 以及抑制氢离子扩散过程的基本策略. 对于电极反应, 探讨了催化位点本征活性的调控、碱金属离子调控界面电场对于二氧化碳还原动力学的影响, 以及碱金属离子与反应中间体的直接配位作用. 然后, 概述了近期无金属离子酸性电解液中二氧化碳电还原技术的进展, 该技术旨在提升二氧化碳电还原性能的可持续性. 介绍了酸性条件二氧化碳电还原过程的理论模拟方法, 提出了将原子尺度的密度泛函理论模拟与电极微反应动力学模拟及介观、宏观尺度传质过程的有限元分析相结合的研究思路. 最后, 总结了促进酸性条件二氧化碳电还原的不同策略, 展望了电极微环境检测、模拟和调控的可能途径, 以及进一步提升酸性条件二氧化碳电还原稳定性及降低成本的策略.

关键词: 二氧化碳还原, 电催化, 酸性电解液, 传质, 阳离子效应

Abstract:

CO2 electroreduction is a promising technique to convert renewable electricity and CO2 to high-value fuels and chemicals. Selectivity, energy efficiency, carbon efficiency and sustainability are the criteria for CO2 electroreduction techniques suitable for industrial application. With alkaline and neutral electrolytes, carbonate formation from CO2 leads to low carbon efficiency. High energy consumption to regenerate alkaline electrolyte and high resistance of neutral electrolyte cause low energy efficiency. Recently, CO2 reduction with acidic electrolyte becomes a hot topic due to its potential to increase carbon efficiency and energy efficiency. Improving the selectivity towards CO2 reduction is challenging in acidic condition. Diverse approaches were proposed to suppress H+ reduction and promote CO2 reduction. However, fundamental issues about cation effect and local pH effect on CO2 reduction in acidic condition are still under debate. Moreover, bicarbonate precipitation in gas diffusion electrode limits the sustainability with acidic electrolyte. This review tries to rationalize the reported strategies to improve the selectivity towards CO2 reduction in acidic condition from mass transport and electrode reactions. Different approaches, including adding alkali cations, surface decoration, nanostructuring, and electronic structure modulation, are designed based on these two aspects. This review also introduces the recent progress in CO2 electroreduction with metal cation-free acidic electrolyte. This strategy is deemed to improve the sustainability.

Key words: Carbon dioxide reduction, Electrocatalysis, Acidic electrolyte, Mass transport, Cation effect