Chinese Journal of Catalysis ›› 2021, Vol. 42 ›› Issue (9): 1439-1444.DOI: 10.1016/S1872-2067(20)63762-7

• Communications • Previous Articles     Next Articles

Alkali metal cation effects on electrocatalytic CO2 reduction with iron porphyrins

Kai Guoa, Haitao Leia, Xialiang Lia, Zongyao Zhangb, Yabo Wanga, Hongbo Guoa, Wei Zhanga, Rui Caoa,*()   

  1. aKey Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, Shaanxi, China
    bChemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
  • Received:2020-12-19 Accepted:2021-01-11 Online:2021-09-18 Published:2021-05-16
  • Contact: Rui Cao
  • About author:* Tel: +86-29-81530726; Fax: +86-29-81530727; E-mail: ruicao@snnu.edu.cn
    Rui Cao (College of Chemistry and Chemical Engineering, Shaanxi Normal University) received the SPP/JPP Young Investigator Awards from International Society of Porphyrins and Phthalocyanines in 2020. Professor Rui Cao received his B.S. degree (2003) in chemistry from Peking University in Beijing, China and his Ph.D. degree (2008) from Emory University in Atlanta, Georgia, USA with Professor Craig L. Hill. He worked as a Postdoctoral Fellow (2008-2009) at Emory University and as the Dreyfus Postdoctoral Fellow (2009-2011) at Massachusetts Institute of Technology with Professor Stephen J. Lippard. In 2011, he became a professor at Renmin University of China, and transferred to Shaanxi Normal University in 2014. His main research interests include bioinorganic chemistry and molecular electrocatalysis for energy-related small molecule activation reactions. Some of his recent progresses using metal porphyrins as catalysts include: (1) demonstrating and controlling homolytic versus heterolytic hydrogen evolution reaction through steric effects, (2) developing porphyrin-appended water-soluble polymers as bioinspired catalysts for both electro- and photocatalytic hydrogen evolution reactions, (3) achieving low overpotential water oxidation at neutral pH and controlling water oxidation selectivity to either O2 or H2O2 with a copper porphyrin, (4) developing an asymmetrical dinuclear cobalt porphyrin for highly efficient and selective oxygen reduction, and (5) engineering carbon materials and metal oxides with molecular catalysts for efficient molecular electrocatalysis. Since 2011 when starting his independent research, Professor Cao has published more than 100 peer-reviewed papers. He joined the editorial Board of Chin. J. Catal. since 2020, Chem. Soc. Rev. since 2019, and Chin. Chem. Lett. since 2017.
  • Supported by:
    Fok Ying-Tong Education Foundation for Outstanding Young Teachers in University;National Natural Science Foundation of China(21573139);National Natural Science Foundation of China(21773146);Fundamental Research Funds for the Central Universities;Research Funds of Shaanxi Normal University

Abstract:

The electrocatalytic CO2 reduction reaction (CO2RR) has attracted increasing attention in recent years. Practical electrocatalysis of CO2RR must be carried out in aqueous solutions containing electrolytes of alkali metal cations such as sodium and potassium. Although considerable efforts have been made to design efficient electrocatalysts for CO2RR and to investigate the structure-activity relationships using molecular model complexes, only a few studies have been investigated the effect of alkali metal cations on electrocatalytic CO2RR. In this study, we report the effect of alkali metal cations (Na+ and K+) on electrocatalytic CO2RR with Fe porphyrins. By running CO2RR electrocatalysis in dimethylformamide (DMF), we found that the addition of Na+ or K+ considerably improves the catalytic activity of Fe chloride tetrakis(3,4,5-trimethoxyphenyl)porphyrin (FeP). Based on this result, we synthesized an Fe porphyrin N18C6-FeP bearing a tethered 1-aza-18-crown-6-ether (N18C6) group at the second coordination sphere of the Fe site. We showed that with the tethered N18C6 to bind Na+ or K+, N18C6-FeP is more active than FeP for electrocatalytic CO2RR. This work demonstrates the positive effect of alkali metal cations to improve CO2RR electrocatalysis, which is valuable for the rational design of new efficient catalysts.

Key words: CO2 reduction, Molecular electrocatalysis, Alkali metal cation effect, Iron porphyrin, Structure-activity relationship