Tailoring local structures of atomically dispersed copper sites for highly selective CO₂ electroreduction

Abstract

Atomically-dispersed copper sites coordinated with nitrogen-doped carbon (Cu–N–C) can provide novel possibilities to enable highly selective and active electrochemical CO₂ reduction reactions. However, the construction of optimal local electronic structures for nitrogen-coordinated Cu sites (Cu–N₄) on carbon remains challenging. Here, we synthesized the Cu–N–C catalysts with atomically-dispersed edge-hosted Cu–N₄ sites (Cu–N₄C₈) located in a micropore between two graphitic sheets via a facile method to control the concentration of metal precursor. Edge-hosted Cu–N₄C₈ catalysts outperformed the previously reported M–N–C catalysts for CO₂-to-CO conversion, achieving a maximum CO Faradaic efficiency (FE_CO) of 96%, a CO current density of –8.97 mA cm^–2 at –0.8 V versus reversible hydrogen electrode (RHE), and over FE_CO of 90% from –0.6 to –1.0 V versus RHE. Computational studies revealed that the micropore of the graphitic layer in edge-hosted Cu–N₄C₈ sites causes the d-orbital energy level of the Cu atom to shift upward, which in return decreases the occupancy of antibonding states in the *COOH binding. This research suggests new insights into tailoring the locally coordinated structure of the electrocatalyst at the atomic scale to achieve highly selective electrocatalytic reactions.

Keywords

atomic local structure / density functional theory / electrochemical CO₂ reduction / metal nitrogen-doped carbon / single-atom catalyst

References

[1] Sanz-Pérez ES, Murdock CR, Didas SA, Jones CW. Direct capture of CO₂ from ambient air. Chem Rev. 2016; 116 (19): 11840- 11876.

[2] Liu H, Zhu Y, Ma J, Zhang Z, Hu W. Recent advances in atomic-level engineering of nanostructured catalysts for electrochemical CO₂ reduction. Adv Funct Mater. 2020; 30 (17): 1910534.

[3] Nielsen DU, Hu X-M, Daasbjerg K, Skrydstrup T. Chemically and electrochemically catalysed conversion of CO₂ to CO with follow-up utilization to value-added chemicals. Nat Catal. 2018; 1 (4): 244- 254.

[4] Long C, Li X, Guo J, et al. Electrochemical reduction of CO₂ over heterogeneous catalysts in aqueous solution: recent progress and perspectives. Small Methods. 2019; 3 (3): 1800369.

[5] Francke R, Schille B, Roemelt M. Homogeneously catalyzed electroreduction of carbon dioxide-methods, mechanisms, and catalysts. Chem Rev. 2018; 118 (9): 4631- 4701.

[6] Cao L, Luo Q, Liu W, et al. Identification of single-atom active sites in carbon-based cobalt catalysts during electrocatalytic hydrogen evolution. Nat Catal. 2019; 2 (2): 134- 141.

[7] Jung E, Shin H, Lee B-H, et al. Atomic-level tuning of Co-N-C catalyst for high-performance electrochemical H₂O₂ production. Nat Mater. 2020; 19 (4): 436- 442.

[8] Wang Y, Cho A, Jia G, et al. Tuning local coordination environments of manganese single-atom nanozymes with multi-enzyme properties for selective colorimetric biosensing. Angew Chem. 2023; 135 (15): e202300119.

[9] Xiao C, Song W, Liang J, et al. P-block tin single atom catalyst for improved electrochemistry in a lithium-sulfur battery: a theoretical and experimental study. J Mater Chem A. 2022; 10 (7): 3667- 3677.

[10] Zhao H, Cao H, Zhang Z, Wang Y-G. Modeling the potentialdependent kinetics of CO₂ electroreduction on single-nickel atom catalysts with explicit solvation. ACS Catal. 2022; 12 (18): 11380- 11390.

[11] Miao Z, Li S, Priest C, Wang T, Wu G, Li Q. Effective approaches for designing stable M-N_x/C oxygen-reduction catalysts for proton-exchange-membrane fuel cells. Adv Mater. 2022; 34 (52): 2200595.

[12] Zhang H, Jin X, Lee J-M, Wang X. Tailoring of active sites from single to dual atom sites for highly efficient electrocatalysis. ACS Nano. 2022; 16 (11): 17572- 17592.

[13] Wang X, Chen Z, Zhao X, et al. Regulation of coordination number over single Co sites: triggering the efficient electroreduction of CO₂. Angew Chem Int Ed. 2018; 57 (7): 1944- 1948.

[14] Hu X-M, Hval HH, Bjerglund ET, et al. Selective CO₂ reduction to CO in water using Earth-abundant metal and nitrogen-doped carbon electrocatalysts. ACS Catal. 2018; 8 (7): 6255- 6264.

[15] Wang Y, Park BJ, Paidi VK, et al. Precisely constructing orbital coupling-modulated dual-atom Fe pair sites for synergistic CO₂ electroreduction. ACS Energy Lett. 2022; 7 (2): 640- 649.

[16] Gao D, Liu T, Wang G, Bao X. Structure sensitivity in singleatom catalysis toward CO₂ electroreduction. ACS Energy Lett. 2021; 6 (2): 713- 727.

[17] Wang L, Wang D, Li Y. Single-atom catalysis for carbon neutrality. Carbon Energy. 2022; 4 (6): 1021- 1079.

[18] Ju W, Bagger A, Hao G-P, et al. Understanding activity and selectivity of metal-nitrogen-doped carbon catalysts for electrochemical reduction of CO₂. Nat Commun. 2017; 8: 944.

[19] Ren W, Tan X, Yang W, et al. Isolated diatomic Ni-Fe metal-nitrogen sites for synergistic electroreduction of CO₂. Angew Chem Int Ed. 2019; 58 (21): 6972- 6976.

[20] Möller T, Ju W, Bagger A, et al. Efficient CO₂ to CO electrolysis on solid Ni-N-C catalysts at industrial current densities. Energy Environ Sci. 2019; 12 (2): 640- 647.

[21] Yang J, Qiu Z, Zhao C, et al. In situ thermal atomization to convert supported nickel nanoparticles into surface-bound nickel single-atom. Angew Chem Int Ed. 2018; 57 (43): 14095- 14100.

[22] Ye Y, Cai F, Li H, et al. Surface functionalization of ZIF-8 with ammonium ferric citrate toward high exposure of Fe-N active sites for efficient oxygen and carbon dioxide electroreduction. Nano Energy. 2017; 38: 281- 289.

[23] Huan TN, Ranjbar N, Rousse G, et al. Electrochemical reduction of CO₂ catalyzed by Fe-N-C materials: a structure-selectivity study. ACS Catal. 2017; 7 (3): 1520- 1525.

[24] Cheng Q, Mao K, Ma L, et al. Encapsulation of iron nitride by Fe-N-C shell enabling highly efficient electroreduction of CO₂ to CO. ACS Energy Lett. 2018; 3 (5): 1205- 1211.

[25] Chen S, Li Y, Bu Z, et al. Boosting CO₂-to-CO conversion on a robust single-atom copper decorated carbon catalyst by enhancing intermediate binding strength. J Mater Chem A. 2021; 9 (3): 1705- 1712.

[26] Yang H, Wu Y, Li G, et al. Scalable production of efficient singleatom copper decorated carbon membranes for CO₂ electroreduction to methanol. J Am Chem Soc. 2019; 141 (32): 12717- 12723.

[27] Karapinar D, Huan NT, Ranjbar Sahraie N, et al. Electroreduction of CO₂ on single-site copper-nitrogen-doped carbon material: selective formation of ethanol and reversible restructuration of the metal sites. Angew Chem Int Ed. 2019; 58 (42): 15098- 15103.

[28] Yang F, Mao X, Ma M, et al. Scalable strategy to fabricate single Cu atoms coordinated carbons for efficient electroreduction of CO₂ to CO. Carbon. 2020; 168: 528- 535.

[29] Pan F, Li B, Sarnello E, et al. Pore-edge tailoring of singleatom iron-nitrogen sites on graphene for enhanced CO₂ reduction. ACS Catal. 2020; 10 (19): 10803- 10811.

[30] Yan C, Li H, Ye Y, et al. Coordinatively unsaturated nickel-nitrogen sites towards selective and high-rate CO₂ electroreduction. Energy Environ Sci. 2018; 11 (5): 1204- 1210.

[31] Li F, Han G-F, Bu Y, et al. Unveiling the critical role of active site interaction in single atom catalyst towards hydrogen evolution catalysis. Nano Energy. 2022; 93: 106819.

[32] Wang Y, Cui X, Zhao J, et al. Rational design of Fe-N/C hybrid for enhanced nitrogen reduction electrocatalysis under ambient conditions in aqueous solution. ACS Catal. 2019; 9 (1): 336- 344.

[33] Guda SA, Guda AA, Soldatov MA, et al. Optimized finite difference method for the full-potential XANES simulations: application to molecular adsorption geometries in MOFs and metal-ligand intersystem crossing transients. J Chem Theory Comput. 2015; 11 (9): 4512- 4521.

[34] Bunău O, Joly Y. Self-consistent aspects of X-ray absorption calculations. J Phys Condens Matter. 2009; 21 (34): 345501.

[35] Kresse G, Hafner J. Ab initio molecular dynamics for liquid metals. Phys Rev B. 1993; 47 (1): 558- 561.

[36] Kresse G, Furthmüller J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys Rev B. 1996; 54 (16): 11169- 11186.

[37] Blöchl PE. Projector augmented-wave method. Phys Rev B. 1994; 50 (24): 17953- 17979.

[38] Kresse G, Joubert D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys Rev B. 1999; 59 (3): 1758- 1775.

[39] Monkhorst HJ, Pack JD. Special points for Brillouin-zone integrations. Phys Rev B. 1976; 13 (12): 5188- 5192.

[40] Nørskov JK, Rossmeisl J, Logadottir A, et al. Origin of the overpotential for oxygen reduction at a fuel-cell cathode. J Phys Chem B. 2004; 108 (46): 17886- 17892.

[41] Rossmeisl J, Qu ZW, Zhu H, Kroes GJ, Nørskov JK. Electrolysis of water on oxide surfaces. J Electroanal Chem. 2007; 607 (1-2): 83- 89.

[42] Peterson AA, Abild-Pedersen F, Studt F, Rossmeisl J, Nørskov JK. How copper catalyzes the electroreduction of carbon dioxide into hydrocarbon fuels. Energy Environ Sci. 2010; 3 (9): 1311- 1315.

[43] Deringer VL, Tchougréeff AL, Dronskowski R. Crystal orbital Hamilton population (COHP) analysis as projected from plane-wave basis sets. J Phys Chem A. 2011; 115 (21): 5461- 5466.

[44] Dronskowski R, Bloechl PE. Crystal orbital Hamilton populations (COHP): energy-resolved visualization of chemical bonding in solids based on density-functional calculations. J Phys Chem. 1993; 97 (33): 8617- 8624.

[45] Maintz S, Deringer VL, Tchougréeff AL, Dronskowski R. LOBSTER: a tool to extract chemical bonding from planewave based DFT. J Comput Chem. 2016; 37 (11): 1030- 1035.

[46] Yin P, Yao T, Wu Y, et al. Single cobalt atoms with precise Ncoordination as superior oxygen reduction reaction catalysts. Angew Chem Int Ed. 2016; 55 (36): 10800- 10805.

[47] Zhang Y, Jiao L, Yang W, Xie C, Jiang H-L. Rational fabrication of low-coordinate single-atom Ni electrocatalysts by MOFs for highly selective CO₂ reduction. Angew Chem Int Ed. 2021; 60 (14): 7607- 7611.

[48] Wang Y, Zhang Z, Jia G, Zheng L, Zhao J, Cui X. Elucidating the mechanism of the structure-dependent enzymatic activity of Fe-N/C oxidase mimics. Chem Commun. 2019; 55 (36): 5271- 5274.

[49] Wang D, Chen Y, Wang H, et al. N-doped porous carbon anchoring on carbon nanotubes derived from ZIF-8/polypyrrole nanotubes for superior supercapacitor electrodes. Appl Surf Sci. 2018; 457: 1018- 1024.

[50] Wan L, Shamsaei E, Easton CD, et al. ZIF-8 derived nitrogendoped porous carbon/carbon nanotube composite for highperformance supercapacitor. Carbon. 2017; 121: 330- 336.

[51] Palaniselvam T, Aiyappa HB, Kurungot S. An efficient oxygen reduction electrocatalyst from graphene by simultaneously generating pores and nitrogen doped active sites. J Mater Chem. 2012; 22 (45): 23799- 23805.

[52] Jiang Z, Sun W, Shang H, et al. Atomic interface effect of a single atom copper catalyst for enhanced oxygen reduction reactions. Energy Environ Sci. 2019; 12 (12): 3508- 3514.

[53] Chen X, Ma D-D, Chen B, et al. Metal-organic frameworkderived mesoporous carbon nanoframes embedded with atomically dispersed Fe-N active sites for efficient bifunctional oxygen and carbon dioxide electroreduction. Appl Catal B. 2020; 267: 118720.

[54] Jeong H-Y, Balamurugan M, Choutipalli VSK, et al. Achieving highly efficient CO₂ to CO electroreduction exceeding 300 mA cm^-2 with single-atom nickel electrocatalysts. J Mater Chem A. 2019; 7 (17): 10651- 10661.

[55] Zhao C, Dai X, Yao T, et al. Ionic exchange of metal-organic frameworks to access single nickel sites for efficient electroreduction of CO₂. J Am Chem Soc. 2017; 139 (24): 8078- 8081.

[56] Fei H, Dong J, Arellano-Jiménez MJ, et al. Atomic cobalt on nitrogen-doped graphene for hydrogen generation. Nat Commun. 2015; 6: 8668.

[57] Jiao L, Wan G, Zhang R, Zhou H, Yu SH, Jiang HL. From metal-organic frameworks to single-atom Fe implanted N-doped porous carbons: efficient oxygen reduction in both alkaline and acidic media. Angew Chem Int Ed. 2018; 57 (28): 8525- 8529.

[58] Zhang H, Hwang S, Wang M, et al. Single atomic iron catalysts for oxygen reduction in acidic media: particle size control and thermal activation. J AmChem Soc. 2017; 139 (40): 14143- 14149.

[59] Yuan K, Lützenkirchen-Hecht D, Li L, et al. Boosting oxygen reduction of single iron active sites via geometric and electronic engineering: nitrogen and phosphorus dual coordination. J Am Chem Soc. 2020; 142 (5): 2404- 2412.

[60] Lai Q, Zheng L, Liang Y, He J, Zhao J, Chen J. Metal-organicframework-derived Fe-N/C electrocatalyst with fivecoordinated Fe-N_x sites for advanced oxygen reduction in acid media. ACS Catal. 2017; 7 (3): 1655- 1663.

[61] Lai Q, Zhu J, Zhao Y, Liang Y, He J, Chen J. MOF-based metal-doping-induced synthesis of hierarchical porous Cu-N/C oxygen reduction electrocatalysts for Zn-air batteries. Small. 2017; 13 (30): 1700740.

[62] Stoupin S, Rivera H, Li Z, et al. Structural analysis of sonochemically prepared PtRu versus Johnson Matthey PtRu in operating direct methanol fuel cells. Phys Chem Chem Phys. 2008; 10 (42): 6430- 6437.

[63] Lais T, Lukashuk L, van de Water L, Hyde TI, Aramini M, Sankar G. Elucidation of copper environment in a Cu-Cr-Fe oxide catalyst through in situ high-resolution XANES investigation. Phys Chem Chem Phys. 2021; 23 (10): 5888- 5896.

[64] Scherdel C, Reichenauer G, Wiener M. Relationship between pore volumes and surface areas derived from the evaluation of N₂-sorption data by DR-, BET- and t-plot. Microporous Mesoporous Mater. 2010; 132 (3): 572- 575.

[65] Boningari T, Inturi SNR, Manousiouthakis VI, Smirniotis PG. Facile synthesis of flame spray pyrolysis-derived magnesium oxide nanoparticles for CO₂ sorption: effect of precursors, morphology, and structural properties. Ind Eng Chem Res. 2018; 57 (28): 9054- 9061.

[66] Pan F, Deng W, Justiniano C, Li Y. Identification of champion transition metals centers in metal and nitrogen-codoped carbon catalysts for CO₂ reduction. Appl Catal B. 2018; 226: 463- 472.

[67] Varela AS, Ranjbar Sahraie N, Steinberg J, Ju W, Oh HS, Strasser P. Metal-doped nitrogenated carbon as an efficient catalyst for direct CO₂ electroreduction to CO and hydrocarbons. Angew Chem Int Ed. 2015; 54 (37): 10758- 10762.

[68] Pan F, Zhang H, Liu K, et al. Unveiling active sites of CO₂ reduction on nitrogen-coordinated and atomically dispersed iron and cobalt catalysts. ACS Catal. 2018; 8 (4): 3116- 3122.

[69] Chan K, Tsai C, Hansen HA, Nørskov JK. Molybdenum sulfides and selenides as possible electrocatalysts for CO₂ reduction. ChemCatChem. 2014; 6 (7): 1899- 1905.

[70] Shi C, Hansen HA, Lausche AC, Nørskov JK. Trends in electrochemical CO₂ reduction activity for open and close-packed metal surfaces. Phys Chem Chem Phys. 2014; 16 (10): 4720- 4727.

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