Catalyzing Electrochemical CO2 REduction to Methanol

Our society is currently facing critical challenges regarding CO₂ emissions and drastic changes in the way we produce energy, chemicals and materials are required in order to tackle global warming. The electrochemical reduction of CO₂ is a key reaction in order to reduce our carbon footprint and a great scientific effort is being made to improve our knowledge and understanding about this complicated process. Recently, cobalt phthalocyanine (CoPc) has drawn tremendous attention due to its capability to electrochemically reduce CO₂and CO to methanol (1-6), a key molecule in the chemical manufacturing industry. Because of its well-defined structure, CoPc provides a model platform to understand reaction mechanism and rationally improve the catalytic activity and stability. In our recent work, through kinetic isotope effect studies and electrokinetic analyses, we identified the protonation of adsorbed CHO as the rate determining step (RDS) for CO₂-to-methanol conversion and we showed that the hydration shell of more acidic alkali cations can enhance CO₂-to-methanon kinetics via faster proton-coupled electron transfer (in the order Li⁺ &gt; Na⁺ &gt; K⁺ &gt; Cs⁺). This conclusion was supported by density functional theory calculations and molecular dynamics simulations. In this contribution, the reaction mechanism of CO₂-to-methanol electroreduction will be discussed, with a particular focus on how proton-coupled electron transfer kinetics and the stability of reaction intermediates can be tuned in order to maximize the faradaic efficiency for methanol production. Moreover, we will discuss the impact of different reaction conditions on the stability of the CoPc catalyst and possible mitigation strategies will be proposed.<br/>References:<br/>Y. Wu, Z. Jiang, X. Lu, Y. Liang and H. Wang, <i>Nature</i>, <b>575</b>, 639 (2019).<br/>C. L. Rooney, M. Lyons, Y. Wu, G. Hu, M. Wang, C. Choi, Y. Gao, C.-W. Chang, G. W. Brudvig, Z. Feng and H. Wang, <i>Angewandte Chemie International Edition</i>, <b>63</b>, e202310623 (2024).<br/>J. Li, B. Shang, Y. Gao, S. Cheon, C. L. Rooney and H. Wang, <i>Nature Synthesis</i>, <b>2</b>, 1194 (2023).<br/>J. Su, C. B. Musgrave, Y. Song, L. Huang, Y. Liu, G. Li, Y. Xin, P. Xiong, M. M.-J. Li, H. Wu, M. Zhu, H. M. Chen, J. Zhang, H. Shen, B. Z. Tang, M. Robert, W. A. Goddard and R. Ye, <i>Nature Catalysis</i>, <b>6</b>, 818 (2023).<br/>E. Boutin, M. Wang, J. C. Lin, M. Mesnage, D. Mendoza, B. Lassalle-Kaiser, C. Hahn, T. F. Jaramillo and M. Robert, <i>Angewandte Chemie International Edition</i>, <b>58</b>, 16172 (2019).<br/>L. Yao, K. E. Rivera-Cruz, P. M. Zimmerman, N. Singh and C. C. L. McCrory, <i>ACS Catalysis</i>, <b>14</b>, 366 (2024).