Engineering Metal Nanoclusters at the Atomic Level for Effective Electrocatalysis

Abstract

With the advances of nanochemistry in the past several decades, a diverse set of nanomaterials has been developed as electrocatalysts with enhanced activity, selectivity, and durability for electrocatalytic reactions. However, it has remained as a long challenge to systematically understand the mechanism of electrocatalytic reactions, which involves multiple protons-coupled electron transfer processes and varied products at the atomic level, intrinsically because of the complexity and polydispersity of the traditional nanomaterials. By sharp contrast, ligand-protected metal nanoclusters (NCs) possess atomically precise structures and abundant active sites, facilitating their applications as effective model electrocatalysts for revealing the mechanism of electrocatalytic reactions. This review summarizes recent progress in atom-level engineering of metal NCs as model catalysts for electrocatalytic reactions. Specifically, we first discuss the effects of metal composition engineering, including doping and size effects, on the electrocatalytic performance of metal NCs. Then similar electrocatalytic discussion extends to ligand effects of metal NCs, where ligand type and coverage engineering are deciphered. Moreover, we discuss how the overall charge and morphology of NCs modify their electrocatalytic performance. The fundamental and methodological insights summarized in this review should serve as useful references guiding the future development of effective metal electrocatalysts in diverse sectors of industry.

Keywords

electrocatalysis / metal nanoclusters / structure-property relationship / synthesis

References

[1] J. D. Holladay, J. Hu, D. L. King, and Y. Wang, “An Overview of Hydrogen Production Technologies,” Catalysis Today 139, no. 4 (2009): 244–260.

[2] M. Carmo, D. L. Fritz, J. Mergel, and D. Stolten, “A Comprehensive Review on Pem Water Electrolysis,” International Journal of Hydrogen Energy 38, no. 12 (2013): 4901–4934.

[3] R. Subbaraman, D. Tripkovic, D. Strmcnik, et al., “Enhancing Hydrogen Evolution Activity in Water Splitting by Tailoring Li⁺-Ni(OH)₂-Pt Interfaces,” Science 334, no. 6060 (2011): 1256–1260.

[4] H. Liu and D. Liang, “A Review of Clean Energy Innovation and Technology Transfer in China,” Renewable and Sustainable Energy Reviews 18, no. 2 (2013): 486–498.

[5] H. Furukawa and O. M. Yaghi, “Storage of Hydrogen, Methane, and Carbon Dioxide in Highly Porous Covalent Organic Frameworks for Clean Energy Applications,” Journal of the American Chemical Society 131, no. 25 (2009): 8875–8883.

[6] L. Malavasi, C. A. J. Fisher, and M. S. Islam, “Oxide-Ion and Proton Conducting Electrolyte Materials for Clean Energy Applications: Structural and Mechanistic Features,” Chemical Society Reviews 39, no. 11 (2010): 4370–4387.

[7] S. L. Li and Q. Xu, “Metal-Organic Frameworks as Platforms for Clean Energy,” Energy & Environmental Science 6, no. 6 (2013): 1656–1683.

[8] B. Obama, “The Irreversible Momentum of Clean Energy,” Science 355, no. 6321 (2017): 126–129.

[9] Y. Chen, S. Ji, C. Chen, Q. Peng, D. Wang, and Y. Li, “Single-Atom Catalysts: Synthetic Strategies and Electrochemical Applications,” Joule 2, no. 7 (2018): 1242–1264.

[10] H. Jin, C. Guo, X. Liu, et al., “Emerging Two-Dimensional Nanomaterials for Electrocatalysis,” Chemical Reviews 118, no. 13 (2018): 6337–6408.

[11] H. Sun, Z. Yan, F. Liu, W. Xu, F. Cheng, and J. Chen, “Self-Supported Transition-Metal-Based Electrocatalysts for Hydrogen and Oxygen Evolution,” Advanced Materials 32, no. 3 (2020): 1806326.

[12] H. F. Wang, L. Chen, H. Pang, S. Kaskel, and Q. Xu, “MOF-Derived Electrocatalysts for Oxygen Reduction, Oxygen Evolution and Hydrogen Evolution Reactions,” Chemical Society Reviews 49, no. 5 (2020): 1414–1448.

[13] J. Zhu, L. Hu, P. Zhao, L. Y. S. Lee, and K. Y. Wong, “Recent Advances in Electrocatalytic Hydrogen Evolution Using Nanoparticles,” Chemical Reviews 120, no. 2 (2020): 851–918.

[14] Y. Da, R. Jiang, Z. Tian, X. Han, W. Chen, and W. Hu, “The Applications of Single-Atom Alloys in Electrocatalysis: Progress and Challenges,” SmartMat 4, no. 1 (2022): e1136.

[15] J. Su, Y. Liu, Y. Song, et al., “Recent Development of Nanomaterials for Carbon Dioxide Electroreduction,” SmartMat 3, no. 1 (2022): 35–53.

[16] J. Greeley, T. F. Jaramillo, J. Bonde, I. Chorkendorff, and J. K. Nørskov, “Computational High-Throughput Screening of Electrocatalytic Materials for Hydrogen Evolution,” Nature Materials 5, no. 11 (2006): 909–913.

[17] J. Suntivich, K. J. May, H. A. Gasteiger, J. B. Goodenough, and Y. Shao-Horn, “A Perovskite Oxide Optimized for Oxygen Evolution Catalysis From Molecular Orbital Principles,” Science 334, no. 6061 (2011): 1383–1385.

[18] M. Gong, D. Y. Wang, C. C. Chen, B.-J. Hwang, and H. Dai, “A Mini Review on Nickel-Based Electrocatalysts for Alkaline Hydrogen Evolution Reaction,” Nano Research 9, no. 1 (2016): 28–46.

[19] M. G. Walter, E. L. Warren, J. R. McKone, et al., “Solar Water Splitting Cells,” Chemical Reviews 110, no. 11 (2010): 6446–6473.

[20] Y. Wang, D. Wang, and Y. Li, “A Fundamental Comprehension and Recent Progress in Advanced Pt-Based ORR Nanocatalysts,” SmartMat 2, no. 1 (2021): 56–75.

[21] X. Zhou, H. Liu, B. Y. Xia, K. Ostrikov, Y. Zheng, and S. Z. Qiao, “Customizing the Microenvironment of CO₂ Electrocatalysis via Three-Phase Interface Engineering,” SmartMat 3, no. 1 (2022): 111–129.

[22] N. Markovic, “Surface Science Studies of Model Fuel Cell Electrocatalysts,” Surface Science Reports 45, no. 4–6 (2002): 117–229.

[23] Y. Liu, C. M. Hangarter, U. Bertocci, and T. P. Moffat, “Oxygen Reduction Reaction on Electrodeposited Pt_100–xNi_x: Influence of Alloy Composition and Dealloying,” The Journal of Physical Chemistry C 116, no. 14 (2012): 7848–7862.

[24] M. Lefèvre, E. Proietti, F. Jaouen, and J. P. Dodelet, “Iron-Based Catalysts With Improved Oxygen Reduction Activity in Polymer Electrolyte Fuel Cells,” Science 324, no. 5923 (2009): 71–74.

[25] Y. Zheng, Y. Jiao, J. Chen, et al., “Nanoporous Graphitic-C₃N₄@ Carbon Metal-Free Electrocatalysts for Highly Efficient Oxygen Reduction,” Journal of the American Chemical Society 133, no. 50 (2011): 20116–20119.

[26] Y. Zheng, Y. Jiao, M. Jaroniec, and S. Z. Qiao, “Advancing the Electrochemistry of the Hydrogen-Evolution Reaction Through Combining Experiment and Theory,” Angewandte Chemie International Edition 54, no. 1 (2015): 52–65.

[27] N. Cheng, S. Stambula, D. Wang, et al., “Platinum Single-Atom and Cluster Catalysis of the Hydrogen Evolution Reaction,” Nature Communications 7, no. 1 (2016): 13638.

[28] Y. Li, H. Wang, L. Xie, Y. Liang, G. Hong, and H. Dai, “MoS₂ Nanoparticles Grown on Graphene: An Advanced Catalyst for the Hydrogen Evolution Reaction,” Journal of the American Chemical Society 133, no. 19 (2011): 7296–7299.

[29] Z. W. She, J. Kibsgaard, C. F. Dickens, I. Chorkendorff, J. K. Nørskov, and T. F. Jaramillo, “Combining Theory and Experiment in Electrocatalysis: Insights Into Materials Design,” Science 355, no. 6321 (2017): eaad4998.

[30] X. Zou and Y. Zhang, “Noble Metal-Free Hydrogen Evolution Catalysts for Water Splitting,” Chemical Society Reviews 44, no. 15 (2015): 5148–5180.

[31] A. Grimaud, O. Diaz-Morales, B. Han, et al., “Activating Lattice Oxygen Redox Reactions in Metal Oxides to Catalyse Oxygen Evolution,” Nature Chemistry 9, no. 5 (2017): 457–465.

[32] I. C. Man, H. Y. Su, F. Calle-Vallejo, et al., “Universality in Oxygen Evolution Electrocatalysis on Oxide Surfaces,” ChemCatChem 3, no. 7 (2011): 1159–1165.

[33] C. C. L McCrory, S. Jung, J. C. Peters, and T. F. Jaramillo, “Benchmarking Heterogeneous Electrocatalysts for the Oxygen Evolution Reaction,” Journal of the American Chemical Society 135, no. 45 (2013): 16977–16987.

[34] N. T. Suen, S. F. Hung, Q. Quan, N. Zhang, Y. J. Xu, and H. M. Chen, “Electrocatalysis for the Oxygen Evolution Reaction: Recent Development and Future Perspectives,” Chemical Society Reviews 46, no. 2 (2017): 337–365.

[35] L. Trotochaud, S. L. Young, J. K. Ranney, and S. W. Boettcher, “Nickel-Iron Oxyhydroxide Oxygen-Evolution Electrocatalysts: The Role of Intentional and Incidental Iron Incorporation,” Journal of the American Chemical Society 136, no. 18 (2014): 6744–6753.

[36] J. Zhang, Z. Zhao, Z. Xia, and L. Dai, “A Metal-Free Bifunctional Electrocatalyst for Oxygen Reduction and Oxygen Evolution Reactions,” Nature Nanotechnology 10, no. 5 (2015): 444–452.

[37] C. T. Dinh, T. Burdyny, M. G. Kibria, et al., “CO₂ Electroreduction to Ethylene via Hydroxide-Mediated Copper Catalysis at an Abrupt Interface,” Science 360, no. 6390 (2018): 783–787.

[38] K. P. Kuhl, E. R. Cave, D. N. Abram, and T. F. Jaramillo, “New Insights Into the Electrochemical Reduction of Carbon Dioxide on Metallic Copper Surfaces,” Energy & Environmental Science 5, no. 5 (2012): 7050–7059.

[39] X. Nie, M. R. Esopi, M. J. Janik, and A. Asthagiri, “Selectivity of CO₂ Reduction on Copper Electrodes: The Role of the Kinetics of Elementary Steps,” Angewandte Chemie International Edition 52, no. 9 (2013): 2459–2462.

[40] A. A. Peterson, F. Abild-Pedersen, F. Studt, J. Rossmeisl, and J. K. Nørskov, “How Copper Catalyzes the Electroreduction of Carbon Dioxide Into Hydrocarbon Fuels,” Energy & Environmental Science 3, no. 9 (2010): 1311–1315.

[41] R. Reske, H. Mistry, F. Behafarid, B. Roldan Cuenya, and P. Strasser, “Particle Size Effects in the Catalytic Electroreduction of CO₂ on Cu Nanoparticles,” Journal of the American Chemical Society 136, no. 19 (2014): 6978–6986.

[42] R. Jin, C. Zeng, M. Zhou, and Y. Chen, “Atomically Precise Colloidal Metal Nanoclusters and Nanoparticles: Fundamentals and Opportunities,” Chemical Reviews 116, no. 18 (2016): 10346–10413.

[43] R. Jin, “Quantum Sized, Thiolate-Protected Gol. Nanoclusters,” Nanoscale 2, no. 3 (2010): 343–362.

[44] Q. Yao, T. Chen, X. Yuan, and J. Xie, “Toward Total Synthesis of Thiolate-Protected Metal Nanoclusters,” Accounts of Chemical Research 51, no. 6 (2018): 1338–1348.

[45] Y. Cao, T. Chen, Q. Yao, and J. Xie, “Diversification of Metallic Molecules Through Derivatization Chemistry of Au₂₅ Nanoclusters,” Accounts of Chemical Research 54, no. 22 (2021): 4142–4153.

[46] J. Yan, B. K. Teo, and N. Zheng, “Surface Chemistry of Atomically Precise Coinage-Metal Nanoclusters: From Structural Control to Surface Reactivity and Catalysis,” Accounts of Chemical Research 51, no. 12 (2018): 3084–3093.

[47] I. Chakraborty and T. Pradeep, “Atomically Precise Clusters of Noble Metals: Emerging Link Between Atoms and Nanoparticles,” Chemical Reviews 117, no. 12 (2017): 8208–8271.

[48] Z. Lei, X. K. Wan, S. F. Yuan, Z. J. Guan, and Q. M. Wang, “Alkynyl Approach Toward the Protection of Metal Nanoclusters,” Accounts of Chemical Research 51, no. 10 (2018): 2465–2474.

[49] R. Jin, H. Qian, Z. Wu, et al., “Size Focusing: A Methodology for Synthesizing Atomically Precise Gold Nanoclusters,” The Journal of Physical Chemistry Letters 1, no. 19 (2010): 2903–2910.

[50] C. Zeng, Y. Chen, A. Das, and R. Jin, “Transformation Chemistry of Gold Nanoclusters: From One Stable Size to Another,” The Journal of Physical Chemistry Letters 6, no. 15 (2015): 2976–2986.

[51] R. P. Carney, J. Y. Kim, H. Qian, et al., “Determination of Nanoparticle Size Distribution Together With Density or Molecular Weight by 2D Analytical Ultracentrifugation,” Nature Communications 2, no. 1 (2011): 335.

[52] A. Ghosh, J. Hassinen, P. Pulkkinen, H. Tenhu, R. H. A. Ras, and T. Pradeep, “Simple and Efficient Separation of Atomically Precise Noble Metal Clusters,” Analytical Chemistry 86, no. 24 (2014): 12185–12190.

[53] Y. Negishi, T. Nakazaki, S. Malola, et al., “A Critical Size for Emergence of Nonbulk Electronic and Geometric Structures in Dodecanethiolate-Protected Au Clusters,” Journal of the American Chemical Society 137, no. 3 (2015): 1206–1212.

[54] T. Chen, Q. Yao, R. R. Nasaruddin, and J. Xie, “Electrospray Ionization Mass Spectrometry: A Powerful Platform for Noble-Metal Nanocluster Analysis,” Angewandte Chemie International Edition 58, no. 35 (2019): 11967–11977.

[55] Q. Yao, X. Yuan, T. Chen, D. T. Leong, and J. Xie, “Engineering Functional Metal Materials at the Atomic Level,” Advanced Materials 30, no. 47 (2018): 1802751.

[56] Q. Yao, Z. Wu, Z. Liu, Y. Lin, X. Yuan, and J. Xie, “Molecular Reactivity of Thiolate-Protected Noble Metal Nanoclusters: Synthesis, Self-Assembly, and Applications,” Chemical Science 12, no. 1 (2021): 99–127.

[57] M. Zhu, C. M. Aikens, F. J. Hollander, G. C. Schatz, and R. Jin, “Correlating the Crystal Structure of a Thiol-Protected Au₂₅ Cluster and Optical Properties,” Journal of the American Chemical Society 130, no. 18 (2008): 5883–5885.

[58] H. Yang, Y. Wang, H. Huang, et al., “All-Thiol-Stabilized Ag₄₄ and Au₁₂Ag₃₂ Nanoparticles With Single-Crystal Structures,” Nature Communications 4, no. 1 (2013): 2422.

[59] S. Hossain, Y. Niihori, L. V. Nair, B. Kumar, W. Kurashige, and Y. Negishi, “Alloy Clusters: Precise Synthesis and Mixing Effects,” Accounts of Chemical Research 51, no. 12 (2018): 3114–3124.

[60] S. Wang, Y. Song, S. Jin, et al., “Metal Exchange Method Using Au₂₅ Nanoclusters as Templates for Alloy Nanoclusters With Atomic Precision,” Journal of the American Chemical Society 137, no. 12 (2015): 4018–4021.

[61] Z. J. Guan, J. J. Li, F. Hu, and Q. M. Wang, “Structural Engineering Toward Gold Nanocluster Catalysis,” Angewandte Chemie 134, no. 51 (2022): e202209725.

[62] X. Kang, Y. Li, M. Zhu, and R. Jin, “Atomically Precise Alloy Nanoclusters: Syntheses, Structures, and Properties,” Chemical Society Reviews 49, no. 17 (2020): 6443–6514.

[63] Y. Li, S. Li, A. V. Nagarajan, et al., “Hydrogen Evolution Electrocatalyst Design: Turning Inert Gold Into Active Catalyst by Atomically Precise Nanochemistry,” Journal of the American Chemical Society 143, no. 29 (2021): 11102–11108.

[64] H. Seong, V. Efremov, G. Park, H. Kim, J. S. Yoo, and D. Lee, “Atomically Precise Gold Nanoclusters as Model Catalysts for Identifying Active Sites for Electroreduction of CO₂,” Angewandte Chemie International Edition 60, no. 26 (2021): 14563–14570.

[65] S. Li, A. V. Nagarajan, D. R. Alfonso, et al., “Boosting CO₂ Electrochemical Reduction With Atomically Precise Surface Modification on Gold Nanoclusters,” Angewandte Chemie International Edition 60, no. 12 (2021): 6351–6356.

[66] K. Kwak and D. Lee, “Electrochemistry of Atomically Precise Metal Nanoclusters,” Accounts of Chemical Research 52, no. 1 (2018): 12–22.

[67] S. Zhuang, D. Chen, L. Liao, et al., “Hard-Sphere Random Close-Packed Au₄₇Cd₂(TBBT)₃₁ Nanoclusters With a Faradaic Efficiency of Up to 96% for Electrocatalytic CO₂ Reduction to CO,” Angewandte Chemie 132, no. 8 (2020): 3097–3101.

[68] Y. Lu, C. Zhang, X. Li, et al., “Significantly Enhanced Electrocatalytic Activity of Au₂₅ Clusters by Single Platinum Atom Doping,” Nano Energy 50, no. 8 (2018): 316–322.

[69] K. Kwak, W. Choi, Q. Tang, et al., “A Molecule-Like PtAu₂₄(SC₆H₁₃)₁₈ Nanocluster as an Electrocatalyst for Hydrogen Production,” Nature Communications 8, no. 1 (2017): 14723.

[70] Q. Tang, Y. Lee, D.-Y. Li, et al., “Lattice-Hydride Mechanism in Electrocatalytic CO₂ Reduction by Structurally Precise Copper-Hydride Nanoclusters,” Journal of the American Chemical Society 139, no. 28 (2017): 9728–9736.

[71] X. K. Wan, J. Q. Wang, and Q. M. Wang, “Ligand-Protected Au₅₅ With a Novel Structure and Remarkable CO₂ Electroreduction Performance,” Angewandte Chemie International Edition 60, no. 38 (2021): 20748–20753.

[72] S. F. Yuan, R. L. He, X. S. Han, J. Q. Wang, Z. J. Guan, and Q. M. Wang, “Robust Gold Nanocluster Protected With Amidinates for Electrocatalytic CO₂ Reduction,” Angewandte Chemie International Edition 60, no. 26 (2021): 14345–14349.

[73] S. Li, A. V. Nagarajan, X. Du, et al., “Dissecting Critical Factors for Electrochemical CO₂ Reduction on Atomically Precise Au Nanoclusters,” Angewandte Chemie International Edition 61, no. 47 (2022): e202211771.

[74] J. Wang, F. Xu, Z. Y. Wang, S. Q. Zang, and T. C. W. Mak, “Ligand-Shell Engineering of a Au₂₈ Nanocluster Boosts Electrocatalytic CO₂ Reduction,” Angewandte Chemie International Edition 61, no. 32 (2022): e202207492.

[75] Z. Liu, H. Tan, B. Li, et al., “Ligand Effect on Switching the Rate-Determining Step of Water Oxidation in Atomically Precise Metal Nanoclusters,” Nature Communications 14, no. 1 (2023): 3374.

[76] D. R. Kauffman, D. Alfonso, C. Matranga, et al., “Probing Active Site Chemistry With Differently Charged Au₂₅q Nanoclusters (q = –1, 0, +1),” Chemical Science 5, no. 8 (2014): 3151–3157.

[77] Y. Lu, Y. Jiang, X. Gao, and W. Chen, “Charge State-Dependent Catalytic Activity of [Au₂₅(SC₁₂H₂₅)₁₈] Nanoclusters for the Two-Electron Reduction of Dioxygen to Hydrogen Peroxide,” Chemical Communications 50, no. 62 (2014): 8464–8467.

[78] S. Zhao, N. Austin, M. Li, et al., “Influence of Atomic-Level Morphology on Catalysis: The Case of Sphere and Rod-Like Gold Nanoclusters for Co₂ Electroreduction,” ACS Catalysis 8, no. 6 (2018): 4996–5001.

[79] S. Li, D. Alfonso, A. V. Nagarajan, et al., “Monopalladium Substitution in Gold Nanoclusters Enhances CO₂ Electroreduction Activity and Selectivity,” ACS Catalysis 10, no. 20 (2020): 12011–12016.

[80] X. Liu, E. Wang, M. Zhou, et al., “Asymmetrically Doping a Platinum Atom Into a Au₃₈ Nanocluster for Changing the Electron Configuration and Reactivity in Electrocatalysis,” Angewandte Chemie International Edition 61, no. 31 (2022): e202207685.

[81] H. Seong, M. Choi, S. Park, et al., “Promoting CO₂-to-CO Electroreduction via the Active-Site Engineering of Atomically Precise Silver Nanoclusters,” ACS Energy Letters 7, no. 12 (2022): 4177–4184.

[82] W. Chen and S. Chen, “Oxygen Electroreduction Catalyzed by Gold Nanoclusters: Strong Core Size Effects,” Angewandte Chemie International Edition 48, no. 24 (2009): 4386–4389.

[83] A. Ghosh, O. F. Mohammed, and O. M. Bakr, “Atomic-Level Doping of Metal Clusters,” Accounts of Chemical Research 51, no. 12 (2018): 3094–3103.

[84] J. L. Zeng, Z. J. Guan, Y. Du, Z. A. Nan, Y. M. Lin, and Q. M. Wang, “Chloride-Promoted Formation of a Bimetallic Nanocluster Au₈₀Ag₃₀ and the Total Structure Determination,” Journal of the American Chemical Society 138, no. 25 (2016): 7848–7851.

[85] Q. Yao, Y. Feng, V. Fung, et al., “Precise Control of Alloying Sites of Bimetallic Nanoclusters via Surface Motif Exchange Reaction,” Nature Communications 8, no. 1 (2017): 1555.

[86] K. Zheng and J. Xie, “Composition-Dependent Antimicrobial Ability of Full-Spectrum Au_xAg_25–x Alloy Nanoclusters,” ACS Nano 14, no. 9 (2020): 11533–11541.

[87] R. Jin, S. Zhao, C. Liu, et al., “Controlling Ag-Doping in [Ag_xAu_25–x(SC₆H₁₁)₁₈]^– Nanoclusters: Cryogenic Optical, Electronic and Electrocatalytic Properties,” Nanoscale 9, no. 48 (2017): 19183–19190.

[88] B. Kumar, T. Kawawaki, N. Shimizu, et al., “Gold Nanoclusters as Electrocatalysts: Size, Ligands, Heteroatom Doping, and Charge Dependences,” Nanoscale 12, no. 18 (2020): 9969–9979.

[89] S. Zhu, T. Li, W. B. Cai, and M. Shao, “CO₂ Electrochemical Reduction as Probed Through Infrared Spectroscopy,” ACS Energy Letters 4, no. 3 (2019): 682–689.

[90] Y. Nie, L. Li, and Z. Wei, “Recent Advancements in Pt and Pt-Free Catalysts for Oxygen Reduction Reaction,” Chemical Society Reviews 44, no. 8 (2015): 2168–2201.

[91] B. Qiao, A. Wang, X. Yang, et al., “Single-Atom Catalysis of CO Oxidation Using Pt₁/Feo_x,” Nature Chemistry 3, no. 8 (2011): 634–641.

[92] J. Zhang, Y. Zhao, X. Guo, et al., “Single Platinum Atoms Immobilized on an Mxene as an Efficient Catalyst for the Hydrogen Evolution Reaction,” Nature Catalysis 1, no. 12 (2018): 985–992.

[93] B. Lim, M. Jiang, P. H. C. Camargo, et al., “Pd-Pt Bimetallic Nanodendrites With High Activity for Oxygen Reduction,” Science 324, no. 5932 (2009): 1302–1305.

[94] T. W. Lyons and M. S. Sanford, “Palladium-Catalyzed Ligand-Directed C-H Functionalization Reactions,” Chemical Reviews 110, no. 2 (2010): 1147–1169.

[95] V. Muravev, G. Spezzati, Y. Q. Su, et al., “Interface Dynamics of Pd-CeO₂ Single-Atom Catalysts During CO Oxidation,” Nature Catalysis 4, no. 6 (2021): 469–478.

[96] O. Pàmies, J. Margalef, S. Cañellas, et al., “Recent Advances in Enantioselective Pd-Catalyzed Allylic Substitution: From Design to Applications,” Chemical Reviews 121, no. 8 (2021): 4373–4505.

[97] W. Choi, G. Hu, K. Kwak, et al., “Effects of Metal-Doping on Hydrogen Evolution Reaction Catalyzed by Mau₂₄ and M₂Au₃₆ Nanoclusters (M = Pt, Pd),” ACS Applied Materials & Interfaces 10, no. 51 (2018): 44645–44653.

[98] Y. Du, J. Xiang, K. Ni, et al., “Design of Atomically Precise Au₂Pd₆ Nanoclusters for Boosting Electrocatalytic Hydrogen Evolution on MoS₂,” Inorganic Chemistry Frontiers 5, no. 11 (2018): 2948–2954.

[99] K. Kwak, W. Choi, Q. Tang, D. Jiang, and D. Lee, “Rationally Designed Metal Nanocluster for Electrocatalytic Hydrogen Production From Water,” Journal of Materials Chemistry A 6, no. 40 (2018): 19495–19501.

[100] C. Yao, Y. Lin, J. Yuan, et al., “Mono-Cadmium vs Mono-Mercury Doping of Au₂₅ Nanoclusters,” Journal of the American Chemical Society 137, no. 49 (2015): 15350–15353.

[101] Q. Li, K. J. Lambright, M. G. Taylor, et al., “Reconstructing the Surface of Gold Nanoclusters by Cadmium Doping,” Journal of the American Chemical Society 139, no. 49 (2017): 17779–17782.

[102] Y. Li, M. J. Cowan, M. Zhou, et al., “Atom-by-Atom Evolution of the Same Ligand-Protected Au₂₁, Au₂₂, Au₂₂Cd₁, and Au₂₄ Nanocluster Series,” Journal of the American Chemical Society 142, no. 48 (2020): 20426–20433.

[103] H. Yang, Y. Wang, J. Lei, et al., “Ligand-Stabilized Au₁₃Cu_x (_x = 2, 4, 8) Bimetallic Nanoclusters: Ligand Engineering to Control the Exposure of Metal Sites,” Journal of the American Chemical Society 135, no. 26 (2013): 9568–9571.

[104] J. Chai, S. Yang, Y. Lv, H. Chong, H. Yu, and M. Zhu, “Exposing the Delocalized Cu-S π Bonds on the Au₂₄Cu₆(SPhtBu)₂₂ Nanocluster and Its Application in Ring-Opening Reactions,” Angewandte Chemie International Edition 58, no. 44 (2019): 15671–15674.

[105] Y. Song, Y. Li, H. Li, et al., “Atomically Resolved Au₅₂Cu₇₂(SR)₅₅ Nanoalloy Reveals Marks Decahedron Truncation and Penrose Tiling Surface,” Nature Communications 11, no. 1 (2020): 478.

[106] G. Deng, H. Yun, M. S. Bootharaju, et al., “Copper Doping Boosts Electrocatalytic CO₂ Reduction of Atomically Precise Gold Nanoclusters,” Journal of the American Chemical Society 145, no. 50 (2023): 27407–27414.

[107] Y. Tan, G. Sun, T. Jiang, et al., “Symmetry Breaking Enhancing the Activity of Electrocatalytic CO₂ Reduction on an Icosahedron-Kernel Cluster by Cu Atoms Regulation,” Angewandte Chemie International Edition 63, no. 4 (2024): e202317471.

[108] L. Liao, S. Zhou, Y. Dai, et al., “Mono-Mercury Doping of Au₂₅ and the HOMO/LUMO Energies Evaluation Employing Differential Pulse Voltammetry,” Journal of the American Chemical Society 137, no. 30 (2015): 9511–9514.

[109] S. Bhat, A. Baksi, S. K. Mudedla, G. Natarajan, V. Subramanian, and T. Pradeep, “Au₂₂Ir₃ (PET)₁₈: An Unusual Alloy Cluster Through Intercluster Reaction,” The Journal of Physical Chemistry Letters 8, no. 13 (2017): 2787–2793.

[110] L. Wang, Z. Tang, W. Yan, H. Yang, Q. Wang, and S. Chen, “Porous Carbon-Supported Gold Nanoparticles for Oxygen Reduction Reaction: Effects of Nanoparticle Size,” ACS Applied Materials & Interfaces 8, no. 32 (2016): 20635–20641.

[111] T. C. Jones, L. Sumner, G. Ramakrishna, et al., “Bulky t-Butyl Thiolated Gold Nanomolecular Series: Synthesis, Characterization, Optical Properties, and Electrocatalysis,” The Journal of Physical Chemistry C 122, no. 31 (2018): 17726–17737.

[112] D. Yang, W. Pei, S. Zhou, J. Zhao, W. Ding, and Y. Zhu, “Controllable Conversion of CO₂ on Non-Metallic Gold Clusters,” Angewandte Chemie International Edition 59, no. 5 (2020): 1919–1924.

[113] A. V. Nagarajan, R. Juarez-Mosqueda, M. J. Cowan, R. Jin, D. R. Kauffman, and G. Mpourmpakis, “Elucidating the Stability of Ligand-Protected Au Nanoclusters Under Electrochemical Reduction of CO₂,” SN Applied Sciences 2, no. 4 (2020): 680.

[114] N. Austin, S. Zhao, J. R. McKone, R. Jin, and G. Mpourmpakis, “Elucidating the Active Sites for CO₂ Electroreduction on Ligand-Protected Au₂₅ Nanoclusters,” Catalysis Science & Technology 8, no. 15 (2018): 3795–3805.

[115] B. Zhang, J. Chen, Y. Cao, O. J. H. Chai, and J. Xie, “Ligand Design in Ligand-Protected Gold Nanoclusters,” Small 17, no. 27 (2021): 2004381.

[116] F. Sun, C. Deng, S. Tian, and Q. Tang, “Oxygen Electrocatalysis by [Au₂₅(SR)₁₈]: Charge, Doping, and Ligand Removal Effect,” ACS Catalysis 11, no. 13 (2021): 7957–7969.

[117] Y. Wang, X.-K. Wan, L. Ren, et al., “Atomically Precise Alkynyl-Protected Metal Nanoclusters as a Model Catalyst: Observation of Promoting Effect of Surface Ligands on Catalysis by Metal Nanoparticles,” Journal of the American Chemical Society 138, no. 10 (2016): 3278–3281.

[118] M. R. Narouz, K. M. Osten, P. J. Unsworth, et al., “N-Heterocyclic Carbene-Functionalized Magic-Number Gold Nanoclusters,” Nature Chemistry 11, no. 5 (2019): 419–425.

[119] X. K. Wan, J. Q. Wang, Z. A. Nan, and Q. M. Wang, “Ligand Effects in Catalysis by Atomically Precise Gold Nanoclusters,” Science Advances 3, no. 10 (2017): e1701823.

[120] F. Bertorelle, I. Russier-Antoine, C. Comby-Zerbino, et al., “Isomeric Effect of Mercaptobenzoic Acids on the Synthesis, Stability, and Optical Properties of Au₂₅(MBA)₁₈ Nanoclusters,” ACS Omega 3, no. 11 (2018): 15635–15642.

[121] C. Comby-Zerbino, F. Bertorelle, P. Dugourd, R. Antoine, and F. Chirot, “Structure and Charge Heterogeneity in Isomeric Au₂₅(MBA)₁₈ Nanoclusters-Insights From Ion Mobility and Mass Spectrometry,” The Journal of Physical Chemistry A 124, no. 28 (2020): 5840–5848.

[122] Y. Du, H. Sheng, D. Astruc, and M. Zhu, “Atomically Precise Noble Metal Nanoclusters as Efficient Catalysts: A Bridge Between Structure and Properties,” Chemical Reviews 120, no. 2 (2020): 526–622.

[123] Y. Liu, H. Tsunoyama, T. Akita, and T. Tsukuda, “Efficient and Selective Epoxidation of Styrene With TBHP Catalyzed by Au₂₅ Clusters on Hydroxyapatite,” Chemical Communications 46, no. 4 (2010): 550–552.

[124] G. Ma, A. Binder, M. Chi, et al., “Stabilizing Gold Clusters by Heterostructured Transition-Metal Oxide-Mesoporous Silica Supports for Enhanced Catalytic Activities for CO Oxidation,” Chemical Communications 48, no. 93 (2012): 11413–11415.

[125] T. Yoskamtorn, S. Yamazoe, R. Takahata, et al., “Thiolate-Mediated Selectivity Control in Aerobic Alcohol Oxidation by Porous Carbon-Supported Au₂₅ Clusters,” ACS Catalysis 4, no. 10 (2014): 3696–3700.

[126] X. Gao and W. Chen, “Highly Stable and Efficient Pd₆(SR)₁₂ Cluster Catalysts for the Hydrogen and Oxygen Evolution Reactions,” Chemical Communications 53, no. 70 (2017): 9733–9736.

[127] K. Sakamoto, S. Masuda, S. Takano, and T. Tsukuda, “Partially Thiolated Au₂₅ Cluster Anchored on Carbon Support via Noncovalent Ligand-Support Interactions: Active and Robust Catalyst for Aerobic Oxidation of Alcohols,” ACS Catalysis 13, no. 5 (2023): 3263–3271.

[128] S. Chen, M. Li, S. Yu, et al., “Ligand Removal of Au₂₅ Nanoclusters by Thermal and Electrochemical Treatments for Selective CO₂ Electroreduction to CO,” The Journal of Chemical Physics 155, no. 5 (2021): 051101.

[129] L. J. Liu, Z. Y. Wang, Z. Y. Wang, R. Wang, S. Q. Zang, and T. C. W. Mak, “Mediating CO₂ Electroreduction Activity and Selectivity over Atomically Precise Copper Clusters,” Angewandte Chemie International Edition 61, no. 35 (2022): e202205626.

[130] S. Li, A. V. Nagarajan, Y. Li, D. R. Kauffman, G. Mpourmpakis, and R. Jin, “The Role of Ligands in Atomically Precise Nanocluster-Catalyzed CO₂ Electrochemical Reduction,” Nanoscale 13, no. 4 (2021): 2333–2337.

[131] D. R. Alfonso, D. Kauffman, and C. Matranga, “Active Sites of Ligand-Protected Au₂₅ Nanoparticle Catalysts for CO₂ Electroreduction to CO,” The Journal of Chemical Physics 144, no. 18 (2016): 184705.

[132] D. Kim, S. Yu, F. Zheng, et al., “Selective CO₂ Electrocatalysis at the Pseudocapacitive Nanoparticle/Ordered-Ligand Interlayer,” Nature Energy 5, no. 12 (2020): 1032–1042.

[133] K. P. Kuhl, T. Hatsukade, E. R. Cave, D. N. Abram, J. Kibsgaard, and T. F. Jaramillo, “Electrocatalytic Conversion of Carbon Dioxide to Methane and Methanol on Transition Metal Surfaces,” Journal of the American Chemical Society 136, no. 40 (2014): 14107–14113.

[134] J. Chen and L. Wang, “Effects of the Catalyst Dynamic Changes and Influence of the Reaction Environment on the Performance of Electrochemical CO₂ Reduction,” Advanced Materials 34, no. 25 (2022): 2103900.

[135] H. Shan, J. Shi, T. Chen, et al., “Modulating Catalytic Activity and Stability of Atomically Precise Gold Nanoclusters as Peroxidase Mimics via Ligand Engineering,” ACS Nano 17, no. 3 (2023): 2368–2377.

[136] Z. Liu, J. Chen, B. Li, et al., “Enzyme-Inspired Ligand Engineering of Gold Nanoclusters for Electrocatalytic Microenvironment Manipulation,” Journal of the American Chemical Society 146, no. 17 (2024): 11773–11781.

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