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Sun H, Liu X, Li Y, Zhang F, Huang X, Sun C, Huang F. Mechanistic insights of electrocatalytic CO 2 reduction by Mn complexes: synergistic effects of the ligands. Dalton Trans 2024; 53:1663-1672. [PMID: 38168800 DOI: 10.1039/d3dt03453d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
The electrocatalytic mechanisms of CO2 reduction catalyzed by pyridine-oxazoline (pyrox)-based Mn catalysts were investigated by DFT calculations. In-depth comparative analyses of pyrox-based and bipyridine-based Mn complexes were carried out. C-OH cleavage is the rate-determining step for both the protonation-first path and the reduction-first path. The free energy of CO2 activation (ΔG1) and the electrons donated by CO ligands in this step are effective descriptors in regulating the C-OH cleavage barrier. The reduction of carboxylate complex 6 (E6) is the potential-determining step for the reduction-first path. Meanwhile, for the protonation-first path, the initial generation (E2) or the regeneration (E8) of active catalyst might be potential-determining. Hirshfeld charge and orbital contribution analysis indicate that E6 is definitely based on the heterocyclic ligand and E2 is related to both the heterocyclic ligand and three CO ligands. Therefore, replacement of the CO ligand by a stronger electron donating ligand can effectively boost the catalytic activity of CO2 reduction without increasing the overpotential in the reduction-first path. This hypothesis is supported by the mechanism calculations of the Mn complex in which the axial CO ligand is replaced by a pyridine or PMe3.
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Affiliation(s)
- Haitao Sun
- Department of Assets and Laboratory Management, College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, P. R. China.
| | - Xueqing Liu
- Department of Assets and Laboratory Management, College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, P. R. China.
| | - Yafeng Li
- Department of Assets and Laboratory Management, College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, P. R. China.
| | - Fang Zhang
- Department of Assets and Laboratory Management, College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, P. R. China.
| | - Xiuxiu Huang
- Department of Assets and Laboratory Management, College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, P. R. China.
| | - Chuanzhi Sun
- Department of Assets and Laboratory Management, College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, P. R. China.
| | - Fang Huang
- Department of Assets and Laboratory Management, College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, P. R. China.
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Qing Y, Wu Q, He S, Zhang P, Xiong Y, Zhang Y, Huang F, Li F, Chen L. Effects of proton tunneling distance on CO 2 reduction by Mn terpyridine species. Dalton Trans 2023; 52:14309-14313. [PMID: 37779480 DOI: 10.1039/d3dt02081a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Herein, we report two manganese terpyridine dicarbonyl complexes, covalently attached to a proximal (1) or distal (2) amide moiety at the ortho position of the pendent phenyl ring as a proton relay. The isomer 1 achieves a turnover frequency (TOF) of 325 s-1 with a minor overpotential of ca. 200 mV. The performance ranks it among the most efficient molecular catalysts for CO2-to-CO conversion, and it is ca.2 orders faster than isomer 2.
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Affiliation(s)
- Yuhang Qing
- State Key Laboratory of Environment-Friendly Energy Materials, School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, P. R. China.
| | - Qianqian Wu
- State Key Laboratory of Environment-Friendly Energy Materials, School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, P. R. China.
| | - Shuanglin He
- State Key Laboratory of Environment-Friendly Energy Materials, School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, P. R. China.
| | - Ping Zhang
- State Key Laboratory of Environment-Friendly Energy Materials, School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, P. R. China.
| | - Ying Xiong
- State Key Laboratory of Environment-Friendly Energy Materials, School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, P. R. China.
| | - Yaping Zhang
- State Key Laboratory of Environment-Friendly Energy Materials, School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, P. R. China.
| | - Fang Huang
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, P. R. China
| | - Fei Li
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, P. R. China
| | - Lin Chen
- State Key Laboratory of Environment-Friendly Energy Materials, School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, P. R. China.
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Hong W, Luthra M, Jakobsen JB, Madsen MR, Castro AC, Hammershøj HCD, Pedersen SU, Balcells D, Skrydstrup T, Daasbjerg K, Nova A. Exploring the Parameters Controlling Product Selectivity in Electrochemical CO 2 Reduction in Competition with Hydrogen Evolution Employing Manganese Bipyridine Complexes. ACS Catal 2023; 13:3109-3119. [PMID: 36910875 PMCID: PMC9990071 DOI: 10.1021/acscatal.2c05951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/30/2023] [Indexed: 02/18/2023]
Abstract
Selective reduction of CO2 is an efficient solution for producing nonfossil-based chemical feedstocks and simultaneously alleviating the increasing atmospheric concentration of this greenhouse gas. With this aim, molecular electrocatalysts are being extensively studied, although selectivity remains an issue. In this work, a combined experimental-computational study explores how the molecular structure of Mn-based complexes determines the dominant product in the reduction of CO2 to HCOOH, CO, and H2. In contrast to previous Mn(bpy-R)(CO)3Br catalysts containing alkyl amines in the vicinity of the Br ligand, here, we report that bpy-based macrocycles locking these amines at the side opposite to the Br ligand change the product selectivity from HCOOH to H2. Ab initio molecular dynamics simulations of the active species showed that free rotation of the Mn(CO)3 moiety allows for the approach of the protonated amine to the reactive center yielding a Mn-hydride intermediate, which is the key in the formation of H2 and HCOOH. Additional studies with DFT methods showed that the macrocyclic moiety hinders the insertion of CO2 to the metal hydride favoring the formation of H2 over HCOOH. Further, our results suggest that the minor CO product observed experimentally is formed when CO2 adds to Mn on the side opposite to the amine ligand before protonation. These results show how product selectivity can be modulated by ligand design in Mn-based catalysts, providing atomistic details that can be leveraged in the development of a fully selective system.
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Affiliation(s)
- Wanwan Hong
- Carbon Dioxide Activation Center (CADIAC), Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Mahika Luthra
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, 0315 Oslo, Norway
| | - Joakim B Jakobsen
- Carbon Dioxide Activation Center (CADIAC), Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Monica R Madsen
- Carbon Dioxide Activation Center (CADIAC), Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Abril C Castro
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, 0315 Oslo, Norway
| | - Hans Christian D Hammershøj
- Carbon Dioxide Activation Center (CADIAC), Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Steen U Pedersen
- Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - David Balcells
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, 0315 Oslo, Norway
| | - Troels Skrydstrup
- Carbon Dioxide Activation Center (CADIAC), Novo Nordisk Foundation (NNF) CO2 Research Center, Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Kim Daasbjerg
- Novo Nordisk Foundation (NNF) CO2 Research Center, Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Ainara Nova
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, 0315 Oslo, Norway.,Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, 0315 Oslo, Norway
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