Advanced searchCitation search
Skip main navigation
Open AccessCCS ChemistryRESEARCH ARTICLES30 May 2025

Atomically Precise Copper Nanoclusters with Cu-N Interfaces Toward Efficient CO2-to-CH4 Electrocatalysis

    https://doi.org/10.31635/ccschem.025.202505606

    Atomic-level active site design and modulation are challenging in catalysis, and atomically precise copper nanoclusters (NCs) present a promising solution due to the well-defined structures and tunable active sites. We report two novel Cu NCs with formamidinate protecting ligands: [Cu33H18(Me-dpf)12](BF4)3 ( Cu33-1, Me-Hdpf = N,N ′-di(5-methyl-2-pyridinyl)formamidine) and [Cu33H16(Me-dpf)12Cl2](BF4)3 ( Cu33-2). In both clusters, all Cu atoms are N-coordinated, forming abundant active Cu-N sites for CO2 reduction reaction (CO2RR). Both Cu33 NCs with highly active Cu+-N sites exhibit remarkable CO2-to-CH4 conversion efficiency. Cu33-1 shows notable CO2-to-CH4 selectivity (57.7%) and stability (FECH4 > 50% after 12 h), achieving a remarkable conversion rate of 0.517 μmol cm−2 s−1 in a flow cell and surpassing all known NC catalysts. Detailed in-situ spectroscopies revealed that these precisely engineered Cu+-N sites stabilize key intermediates *CHO and *OCH2, significantly promoting CH4 formation. This study underscores precise engineering of active sites, providing valuable insights for designing highly efficient NC catalysts for CO2 conversion.

    Introduction

    Atomically precise metal nanoclusters (NCs) have emerged as highly promising materials for catalytic applications, offering unique advantages due to their absolute monodispersity.1–9 This structural precision enables fundamental insights into catalysis, including the precise identification of active sites, the establishment of atomic-level structure–activity relationships, and the elucidation of catalytic mechanisms. Among them, Cu NCs have emerged as cost-effective alternatives to their noble metal counterparts (Au and Ag), showing promise for the electrochemical CO2 reduction reaction (CO2RR), a promising avenue for carbon neutrality.10–16 Yet, only a few Cu NCs, such as Cu32H20L112 (L1 = S2P(OiPr)2),17 Cu8(tBuS)4(L2)4 (L2 = O-ethyl carbonodithiolate),18 Cu6(MBD)6 (MBD = 2-mercaptobenzimidazole),19 Cu4(MMI)4 (MMI = 2-mercapto-1-methylimidazole),20 and Cu38O(TC4A)4(C5H11C≡C)16(OAc)4 (TC4A = Thiacalix[4]arene),21 have been reported for CO2RR, warranting further investigation.

    Among CO2RR products, methane stands out because of its high energy density and well-established storage and transportation infrastructure. However, selective CH4 production on Cu catalysts is hindered by the complex reaction pathways and competing side reaction. The key process in the conversion of CO2-to-CH4 conversion is the protonation of CO* to CHO*, requiring optimal binding strength of CO* intermediate on the surface of catalysts: weak binding results in CO gas desorption, whereas strong binding favors competitive CO* dimerization to C2 products.21–24 Modulating the coordination environment and electronic structure of Cu-based catalytic sites can effectively adjust the adsorption strength of intermediates. Particularly, the N-modified-Cu sites are promising for facilitating electrocatalytic CO2RR toward CH4,19,20 due to the suitable binding of CO* intermediate on the Cu-N sites.

    The active sites in NCs catalysts are abundant and tunable,25–29 providing an effective strategy to engineer N-modified Cu sites. Recent studies have introduced nitrogen donors into thiolate-protected Cu NCs, thus formed Cu+-NS sites increase the CO* binding strength, which favors the formation of high-value products (FECH4 = 42.5% and FEC2H4 = 23%).19 To achieve economically viable CO2-to-CH4 conversion at a large scale, abundant Cu-N sites with medium CO* binding strength is highly desirable. Consequently, Cu+-N sites with homoleptic-nitrogen-donors may stabilize key intermediates *CO and be a promising candidate for high CO2RR selectivity and productivity toward CH4. To this end, our strategy is to employ bis(2-pyridyl)formamidinate (dpf) in the synthesis of Cu NCs. Dpf features two amidinate N and two pyridyl N donors, facilitating the formation of abundant and well-engineered Cu-N sites.

    Herein, we report two novel copper NCs with abundant Cu+-N sites on the cluster surface, namely [Cu33H18(Me-dpf)12](BF4)3 ( Cu33-1, Me-Hdpf = N,N′-di(5-methyl-2-pyridinyl)formamidine) and [Cu33H16(Me-dpf)12Cl2](BF4)3 ( Cu33-2). For the first time, all-nitrogen-donors NCs are used for CO2 electrocatalysis. These two clusters, especially Cu33-1, demonstrate high CO2-to-CH4 Faradaic efficiency. Cu33-1 shows notable CO2-to-CH4 selectivity (57.7%) and stability (FECH4 > 50% after 12 h). Remarkably, near industrial scale jCH4 and CO2-to-CH4 conversion rates were recorded at −398 mA cm−2 and 0.517 μmol cm−2 s−1, respectively. The excellent performance of Cu33-1 surpasses all known NC catalysts in CO2-to-CH4 conversion.

    Experimental Methods

    Synthesis

    Cu33-1 was synthesized by reducing Cu(MeCN)4BF4, Me-Hdpf, and Et3N in toluene/MeOH with tBuNH2·BH3. Using CHCl3/MeOH and NaBH4 yielded Cu33-2. Hexane diffusion into CH2Cl2 solutions provided single crystals for X-ray diffraction. Detailed synthesis procedures can be found in the Supplementary Materials.

    X-ray crystallography

    Crystal data for Cu33-1: C156H174B3Cu33F12N48, monoclinic, P21/c, a = 33.6147(8) Å, b = 17.2194(6) Å, c = 33.2012(14) Å, β = 90.773(3)°, V = 19215.9(11) Å3, Z = 4, T = 173 K, 118172 reflections measured, 18120 unique (Rint = 0.1066), final R1 = 0.0708, wR2 = 0.1989 for 38939 observed reflections [I > 2σ(I)]. CCDC 2381039 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre.

    Crystal data for Cu33-2: C156H172B3Cu33F12N48Cl2, monoclinic, C2/c, a = 29.8125(3) Å, b = 27.9217(3) Å, c = 31.2857(3) Å, β = 110.9080(10)°, V = 24327.9(5) Å3, Z = 4, T = 173 K, 91558 reflections measured, 20910 unique (Rint = 0.0597), final R1 = 0.0554, wR2 = 0.1794 for 24968 observed reflections [I > 2σ(I)]. CCDC 2381040 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre.

    Results and Discussion

    Synthesis and crystal structure

    The preparation of Me-Hdpf ligand followed the literature procedure.30 The synthesis of Cu33-1 involves the direct reduction of a mixture of Cu(MeCN)4BF4, Me-Hdpf, and Et3N in a mixed toluene/MeOH solvent with a mild reducing agent, tBuNH2·BH3. With different reaction solvent (CHCl3/MeOH) and reducing agent (NaBH4), Cu33-2 with a similar kernel was yielded ( Supporting Information Figure S1). Diffusion of hexane into the CH2Cl2 solutions of these Cu NCs gave high-quality single crystals suitable for X-ray diffraction ( Supporting Information Figure S2). The reaction solvent was found to play an important role in the formation of the clusters. The chlorides in Cu33-2 came from CHCl3 through NEt3-mediated C–Cl bond cleavage as reported previously.31 Further attempts to prepare Cu33-2 with the addition of a small amount of chlorides (Ph4PCl, CuCl) were unsuccessful, indicating that the slow release of chlorides in situ is crucial for the formation of Cu33-2.

    Cu33-1 and Cu33-2 crystallized in the monoclinic P21/c and C2/c space group, respectively ( Supporting Information Tables S1, S4, and S5). Cu33-1 consists of a cationic cluster [Cu33(Me-dpf)12H18]3+, while Cu33-2 contains a cation cluster [Cu33(Me-dpf)12H16Cl2]3+ (Figure 1a,b). Both clusters comprise a tightly packed Cu33 kernel of C2 symmetry, which are protected by 12 dpf ligands. The counterions are three BF4– anions. Unlike the various binding motifs in Cu11, Cu20, Ag52, and Ag53 NCs,30,32,33 all the dpf ligands of three NCs adopt the same μ4-bridging mode with one copper atom attached to a N donor, and the Cu–N bond lengths are from 1.946(4) to 2.101(3) Å.

    Figure 1

    Figure 1 | Crystal structures and mass spectra. (a, b) Molecular structure of (a) Cu33-1, and (b) Cu33-2 with hydrogen atoms and BF4− anions omitted for clarity. (c, d) Core–shell structure of the (c) Cu33-1 and (d) Cu33-2. Color code: grey, C; bright green, Cl; dark blue, N; green, purple and orange, Cu. (e, f) Mass spectra of (e) Cu33-1 and (f) Cu33-2, in positive mode. Inset: the experimental isotropic pattern (black) and simulated (red) data.

    The 33 copper atoms in Cu33-1 can be dissected into two densely packed layers with linear edges ( Supporting Information Figure S3). The two pyridyl N atoms in the linear dpf ligand are approximately 7.18 Å apart, and the span distances of the four Cu atoms are from 7.25 to 7.69 Å. The Cu⋯Cu distances within the Cu33 skeleton range from 2.4790(20) to 3.0160(17) Å, with an average distance of 2.6675 Å ( Supporting Information Table S1). Alternatively, it can also be viewed as a Cu18 inner core wrapped by a Cu15 loop ( Supporting Information Figure S4 and Figure 1c). In Cu33-2, a pair of diagonal Cu corner atoms is replaced by chlorides, and another pair of Cu corner atoms are introduced in the other diagonal direction. The metal skeleton can be viewed as a core surrounded by a Cu15Cl2 loop (Figure 1d). Similar bond lengths for Cu33-2 closely resemble those in Cu33-1. The multidentate nitrogen-donor-protected Cu NCs provide abundant Cu-N sites, making them promising for CO2RRs to high-energy-density hydrocarbons.19,34,35

    Electrospray ionization mass spectrometry (ESI-MS) in positive mode was employed to determine the composition and the charge state of the three clusters with CH2Cl2 as the solvent. As shown in Figure 1e, two prominent peaks for Cu33-1 were observed at m/z = 1662.7 and 2537.5, corresponding to the molecular ion [Cu33(Me-dpf)12H18(CH2Cl2)2]3+ and [Cu33(Me-dpf)12H18(BF4)(CH2Cl2)2]2+. Similarly, Cu33-2 gave two prominent peaks, corresponding to [Cu33(Me-dpf)12H16Cl2(CH2Cl2)2]3+ (m/z = 1685.3) and [Cu33(Me-dpf)12H16Cl2(BF4)(CH2Cl2)2]2+ (m/z = 2571.5), respectively (Figure 1f). The observed isotopic patterns of these NCs are in perfect agreement with the simulated.

    The X-ray photoelectron spectroscopy (XPS) presents the Cu 2p1/2 and 2p3/2 peaks at 952.5 and 932.7 eV, respectively (Figure 2a and Supporting Information Figure S5). In the Cu L-inner level-M-inner level-M-inner level electron transition (LMM) Auger spectrum, the shoulder peak at 573.2 eV represents the 1S state of L3M45M45 relaxations, where the major component at 570.5 eV is associated with Cu (+1) species (Figure 2b).36,37 In order to verify the exact number of hydrides in Cu33-2, the corresponding deuterated analog was prepared and investigated by ESI-MS. However, we were not able to synthesize Cu33-1-D because deuterated tBuNH2·BH3 is not commercially available. The mass difference of m/z = 5.4 between [Cu33(Me-dpf)12H16Cl2(CH2Cl2)2]3+ and [Cu33(Me-dpf)12D16Cl2(CH2Cl2)2]3+ confirms the incorporation of 16 deuterides in Cu33-2 (Figure 2c,d and Supporting Information Figure S6). Density functional theory (DFT) calculations were applied to determine the positions of hydrides within the framework ( Supporting Information Figure S7). The ESI-MS and X-ray data indicate that the N-modified Cu sites for Cu33 NCs exhibit an oxidation state of +1.

    Figure 2

    Figure 2 | XPS spectroscopy and deuterated mass spectra. XPS spectroscopy of (a, b) Cu33-2. ESI-MS of (c) Cu33-2-D, in positive mode. (d) The experimental (black) and simulated (red) isotropic patterns.

    The parallel arrangement of amidinate ligands is crucial for forming tightly packed and stable Cu clusters. The cluster structure is consolidated by the ligand bridging and interligand interactions. Both Cu33-1 and Cu33-2 have 12 dpf ligands. There are four dpf ligands on the upper and lower layers (gray), respectively. There are π⋯π interactions between these dpf ligands with centroid-to-centroid distances between the neighboring pyridyl groups in the range of 3.368–3.979 Å (Figure 3a,b and Supporting Information Figure S10). These ligands hold copper atoms together with multiple N binding, favoring the formation of compact copper NCs ( Supporting Information Figure S8). Clusters protected by multidentate N ligands exhibit excellent stability ( Supporting Information Figure S9), which is in accordance with previous studies.32,38 Hydrophobic organic ligands on the cluster surfaces may favor the inhibition of competitive hydrogen evolution reactions during CO2RR.

    Figure 3

    Figure 3 | π⋯π interactions and Cu–N sites. π⋯π interactions between the dpf ligands at the surface of (a) Cu33-1 and (b) Cu33-2. The gray pyridine groups participate in the stacking, while the orange ones are not. Surface protection of (c) Cu33-1 and (d) Cu33-2 kernel showing the linear and parallel arrangement of N4 units.

    In Cu33-1, eight pyridyl rings from the remaining four dpf ligands do not participate in the stacking, while Cu33-2 includes two additional pyridine groups in the stacking. The multidentate amine ligand has a flexible structure and side-facing dpf ligands of Cu33-2 involved in π⋯π stacking exhibit larger torsion angles compared to those of Cu33-1 ( Supporting Information Figure S11). The torsion affects metal site exposure and accompanied π⋯π interactions may influence catalyst activation and accessibility.30,32,39,40 In both clusters, all Cu atoms are N-coordinated, forming abundant Cu+-N sites (Figure 3c,d). This has been proven effective in stabilizing the key intermediate CO*, indicating the significant potential of these Cu NCs in hydrocarbon production through electrocatalysis.

    Electrocatalytic performance

    The electrochemical performance of Cu33 NCs for CO2RR was investigated in a three-electrode H-cell system with a CO2-saturated aqueous 0.1 M KHCO3 solution as the electrolyte ( Supporting Information Figure S12). Gas chromatography analysis was used to identify the production of H2, CO, CH4, and C2H4 ( Supporting Information Figures S13 and S14), and 1H nuclear magnetic resonance was measured to detect liquid byproducts ( Supporting Information Figures S15 and S16). As shown in Figure 4a and Supporting Information Figure S17, CH4 was identified as the main product of CO2RR with both Cu33 NCs as the catalysts, due to their similar structures and Cu+-N sites ( Supporting Information Figures S18 and S19). The maximum Faradaic efficiency (FE) was 57.74% for Cu33-1 at −1.6 V versus the reversible hydrogen electrode (RHE), corresponding to a partial current density (jCH4) of −5.3 mA cm−2 ( Supporting Information Figure S20). Meanwhile, the FE of liquid and other gas products was significantly suppressed (Figure 4b and Supporting Information Figure S21).

    Figure 4

    Figure 4 | CO2RR performance. FEs of CO2RR (a) gas products and (b) overall at different potentials for Cu33-1 in H-cell. (c) Nyquist plots of Cu NCs. Inset: Equivalent circuit model and Hirshfeld surfaces of Cu33-1. (d) Time-dependent total current density and FECH4 for Cu33-1 recorded at −1.6 V vs RHE in H-cell.

    The similarity in CH4 selectivity between Cu33-1 and Cu33-2 can be attributed to their comparable geometric structures, electronic properties, and the reaction pathway. Cu33-1 exhibits a slightly higher Faradaic efficiency ( Supporting Information Figure S22), probably due to the inhibitory effect of π-conjugated stacking pyridine rings on the accessibility of the reactants in Cu33-2 ( Supporting Information Figure S23).41,42 The electrochemical impedance spectroscopy (Figure 4c, Supporting Information Figure S24 and Table S3) reveals that the Cu33-1 shows a lower charge transfer resistance (Rct), indicating faster charge transfer and reaction kinetics. Consequently, Cu33-1 exhibits a slightly higher productivity for the CO2-to-CH4 electrocatalysis while maintaining satisfactory stability.

    We performed the long-term durability test of Cu33-1 at a constant potential of −1.6 V versus RHE for more than 12 h and found that FECH4 remains above 50% (Figure 4d). This stability is attributed to the π⋯π interaction of the amine ligand on the metal cluster surface, favoring maintenance of the structural integrity (Figure 3a,b). Postelectrolysis durability testing ( Supporting Information Figures S25–S29), including ultraviolet–visible, ESI-MS, and XPS analyses, confirmed that the NCs retained their original structural characteristics. These results underscore the stability and integrity of the Cu NCs under CO2 reduction conditions.

    Flow-cell performance and in-situ spectroscopy

    Furthermore, the electrochemical CO2RR performance was assessed in a 1 M KOH using a flow cell device (Figure 5a and Supporting Information Figure S30). The results indicate that both Cu33 NCs exhibited remarkable CO2-to-CH4 activity. Specifically, the Cu33-1 catalyst achieved the highest Faradaic efficiency for CH4 at 56.1% when operated at −1.6 V versus RHE. Notably, the jCH4 and CO2-to-CH4 conversion rate was recorded at industry-level −398 mA cm−2 and 0.517 μmol cm−2 s−1, respectively (Figure 5b). These values surpass those of the start-of-the-art Cu-based NC catalysts ( Supporting Information Table S2).

    Figure 5

    Figure 5 | Flow-cell performance and in-situ Fourier transform infrared spectra. (a) Scheme of applied flow cell. (b) Partial current density of CH4, C2H4, CO, and H2, along with Faraday efficiency of CH4 at different potential on Cu33-1, in a flow cell device. (c, d) In-situ ATR-SEIRAS spectra of the (c) Cu33-1 and (d) Cu33-2 collected under the potential from −0.4 to −1.3 V vs RHE during CO2RR.

    In-situ electrochemical attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) measurements were conducted to reveal the catalytic mechanism and reaction pathway through tracing reaction intermediates (Figure 5c,d). As the potential becomes more negative, a gradual increase in intensity of the peaks at 1278 and 1406 cm−1, corresponding to the C–O stretch and symmetric vibration of the *COOH intermediate.21 These peaks indicate the activation and reduction of CO2. The *COOH intermediates is a widely recognized as a crucial intermediate for electrochemical CO2 reduction to CO or CH4. In addition, a visible peak represented for H2O at around 1640 cm−1 (bending vibrations of adsorbed water molecules) increased negatively with increasing the applied potential, indicating H2O consumption. We detect peaks at 1578 and 1168 cm−1, associated with the *OCCOH intermediate, which is involved in C–C coupling and C2+ product formation.43

    Importantly, additional peaks at 1033 and 1780 cm−1, corresponding to *CHO and *OCH2 intermediates, become prominent at progressively negative potentials, underscoring their roles in the CH4 production pathway. The robust adsorption of *CO is crucial for its hydrogenation to generate CHO*, which is a key intermediate for CO2-to-CH4 pathway. CO intermediates with π anti-bonding is a soft base, which shows weak CO* adsorption on the relatively hard acid Cun+-N sites (1 < n < 2) in most of Cu-based catalysts. Thus, lower Cu oxidation states exhibit better CO* binding strength. Additionally, ligand environment in our multidentate-amine-protected Cu NCs promotes lower-oxidation-state Cu+-N sites, as supported by single-crystal data, ESI-MS, and XPS characterizations. In-situ infrared spectra further show pronounced *CHO and *OCH2 peaks, indicating that the Cu+-N sites enhance *CO hydrogenation, thereby optimizing selectivity and productivity in CO2-to-CH4 conversion ( Supporting Information Figure S31).

    Based on these observations, we propose that the CO2 reduction pathway on these NCs begins with CO2 adsorption, followed by proton-coupled electron transfer steps that form *COOH. The *COOH species then undergoes proton-coupled electron transfer, releasing H2O to form *CO. Then this intermediate undergoes sequential proton-coupled electron transfer reactions leading to *CHO→*OCH2→*OCH3, ultimately producing CH4.

    Conclusion

    In summary, we have developed an efficient strategy to precisely control Cu-N sites in atomically precise NCs for CO2RR. The homoleptic-nitrogen-donors-protected Cu NCs show remarkable intrinsic activity of CO2RR. Cu33-1 featuring abundant and accessible Cu+-N sites with high structural integrity, facilitates the hydrogenation of *CO to generate CHO*. Thus, the NC demonstrates exceptional CO2-to-CH4 selectivity, surpassing all known NC catalysts. These findings highlight the importance of precise active site engineering, which will trigger more possibilities for developing efficient and durable NC catalysts in CO2 conversion.

    Supporting Information

    Supporting Information is available and includes experimental procedures, DFT calculation results, crystallographic information, and characterizations.

    Conflict of Interest

    There is no conflict of interest to report.

    Funding Information

    This work was supported by the National Key R&D Program of China (grant no. 2022YFA1503900) the National Natural Science Foundation of China (grant nos. 92361301 and 22401114), the Basic Research Program of Jiangsu (grant no. BK20241604), and the Fundamental Research Funds for the Central Universities (grant no. JUSRP202401026).

    Acknowledgments

    The calculations were performed by using supercomputers at Tsinghua National Laboratory for Information Science and Technology. The authors acknowledge the Tsinghua Xuetang Talents Program for providing computational resources. The authors acknowledge Mr. Jiang from Scientific Compass (www.shiyanjia.com) for providing assistance with the XPS analysis.

    References

    • 1. Wan X.-K.; Wang J.-Q.; Nan Z.-A.; Wang Q.-M.Ligand Effects in Catalysis by Atomically Precise Gold Nanoclusters.Sci. Adv.2017, 3, e1701823. Google Scholar
    • 2. Shi W.-Q.; Zeng L.; He R.-L.; Han X.-S.; Guan Z.-J.; Zhou M.; Wang Q.-M.Near-Unity NIR Phosphorescent Quantum Yield from a Room-Temperature Solvated Metal Nanocluster.Science2024, 383, 326–330. Google Scholar
    • 3. Wang J.-Q.; He R.-L.; Liu W.-D.; Feng Q.-Y.; Zhang Y.-E.; Liu C.-Y.; Ge J.-X.; Wang Q.-M.Integration of Metal Catalysis and Organocatalysis in a Metal Nanocluster with Anchored Proline.J. Am. Chem. Soc.2023, 145, 12255–12263. Google Scholar
    • 4. Jin R.; Li G.; Sharma S.; Li Y.; Du X.Toward Active-Site Tailoring in Heterogeneous Catalysis by Atomically Precise Metal Nanoclusters with Crystallographic Structures.Chem. Rev.2021, 121, 567–648. Google Scholar
    • 5. Du Y.; Sheng H.; Astruc D.; Zhu M.Atomically Precise Noble Metal Nanoclusters as Efficient Catalysts: A Bridge Between Structure and Properties.Chem. Rev.2020, 120, 526–622. Google Scholar
    • 6. Kwak K.; Lee D.Electrochemistry of Atomically Precise Metal Nanoclusters.Acc. Chem. Res.2019, 52, 12–22. Google Scholar
    • 7. Gupta R. K.; Wang Z.; Mohan B.; Tung C.-H.; Sun D.Advancements in Atomically Precise Nanocluster Protected by Thiacalix[4]arene.Adv. Mater.2024, 36, 2410054. Google Scholar
    • 8. Wang X.; Yin B.; Jiang L.; Yang C.; Liu Y.; Zou G.; Chen S.; Zhu M.Ligand-Protected Metal Nanoclusters as Low-Loss, Highly Polarized Emitters for Optical Waveguides.Science2023, 381, 784–790. Google Scholar
    • 9. Tang Q.; Hu G.; Fung V.; Jiang D.-E.Insights into Interfaces, Stability, Electronic Properties, and Catalytic Activities of Atomically Precise Metal Nanoclusters from First Principles.Acc. Chem. Res.2018, 51, 2793–2802. Google Scholar
    • 10. Wan X. K.; Wang J. Q.; Wang Q. M.Ligand-Protected Au55 with a Novel Structure and Remarkable CO2 Electroreduction Performance.Angew. Chem. Int. Ed.2021, 60, 20748–20753. Google Scholar
    • 11. Seong H.; Efremov V.; Park G.; Kim H.; Yoo J. S.; Lee D.Atomically Precise Gold Nanoclusters as Model Catalysts for Identifying Active Sites for Electroreduction of CO2.Angew. Chem. Int. Ed.2021, 60, 14563–14570. Google Scholar
    • 12. Qin L.; Sun F.; Ma X.; Ma G.; Tang Y.; Wang L.; Tang Q.; Jin R.; Tang Z.Homoleptic Alkynyl-Protected Ag15 Nanocluster with Atomic Precision: Structural Analysis and Electrocatalytic Performance Toward CO2 Reduction.Angew. Chem. Int. Ed.2021, 60, 26136–26141. Google Scholar
    • 13. Kulkarni V. K.; Khiarak B. N.; Takano S.; Malola S.; Albright E. L.; Levchenko T. I.; Aloisio M. D.; Dinh C. T.; Tsukuda T.; Hakkinen H.; Crudden C. M.N-Heterocyclic Carbene-Stabilized Hydrido Au24 Nanoclusters: Synthesis, Structure, and Electrocatalytic Reduction of CO2.J. Am. Chem. Soc.2022, 144, 9000–9006. Google Scholar
    • 14. Narouz M. R.; Osten K. M.; Unsworth P. J.; Man R. W. Y.; Salorinne K.; Takano S.; Tomihara R.; Kaappa S.; Malola S.; Dinh C. T.; Padmos J. D.; Ayoo K.; Garrett P. J.; Nambo M.; Horton J. H.; Sargent E. H.; Hakkinen H.; Tsukuda T.; Crudden C. M.N-Heterocyclic Carbene-Functionalized Magic-Number Gold Nanoclusters.Nat. Chem.2019, 11, 419–425. Google Scholar
    • 15. Sun Y.; Liu X.; Xiao K.; Zhu Y.; Chen M.Active-Site Tailoring of Gold Cluster Catalysts for Electrochemical CO2 Reduction.ACS Catal.2021, 11, 11551–11560. Google Scholar
    • 16. Liu X.; Wang E.; Zhou M.; Wan Y.; Zhang Y.; Liu H.; Zhao Y.; Li J.; Gao Y.; Zhu Y.Asymmetrically Doping a Platinum Atom into a Au38 Nanocluster for Changing the Electron Configuration and Reactivity in Electrocatalysis.Angew. Chem. Int. Ed.2022, 61, e202207685. Google Scholar
    • 17. Tang Q.; Lee Y.; Li D. Y.; Choi W.; Liu C. W.; Lee D.; Jiang D. E.Lattice-Hydride Mechanism in Electrocatalytic CO2 Reduction by Structurally Precise Copper-Hydride Nanoclusters.J. Am. Chem. Soc.2017, 139, 9728–9736. Google Scholar
    • 18. Liu L. J.; Wang Z. Y.; Wang Z. Y.; Wang R.; Zang S. Q.; Mak T. C. W.Mediating CO2 Electroreduction Activity and Selectivity over Atomically Precise Copper Clusters.Angew. Chem. Int. Ed.2022, 61, e202205626. Google Scholar
    • 19. Wu Q.-J.; Si D.-H.; Sun P.-P.; Dong Y.-L.; Zheng S.; Chen Q.; Ye S.-H.; Sun D.; Cao R.; Huang Y.-B.Atomically Precise Copper Nanoclusters for Highly Efficient Electroreduction of CO2 Towards Hydrocarbons via Breaking the Coordination Symmetry of Cu Site.Angew. Chem. Int. Ed.2023, 62, e202306822. Google Scholar
    • 20. Li J.-K.; Dong J.-P.; Liu S.-S.; Hua Y.; Zhao X.-L.; Li Z.; Zhao S.-N.; Zang S.-Q.; Wang R.Promoting CO2 Electroreduction to Hydrocarbon Products via Sulfur-Enhanced Proton Feeding in Atomically Precise Thiolate-Protected Cu Clusters.Angew. Chem. Int. Ed.2024, 63, e202412144. Google Scholar
    • 21. Mu W.-L.; Li L.; Cong X.-Z.; Chen X.; Xia P.; Liu Q.; Wang L.; Yan J.; Liu C.Hierarchical Assembly of High-Nuclearity Copper(I) Alkynide Nanoclusters: Highly Effective CO2 Electroreduction Catalyst Toward Hydrocarbons.J. Am. Chem. Soc.2024, 146, 28131–28140. Google Scholar
    • 22. Chen L.; Wang L.; Shen Q.; Liu Y.; Tang Z.All-Alkynyl-Protected Coinage Metal Nanoclusters: From Synthesis to Electrocatalytic CO2 Reduction Applications.Mater. Chem. Front.2023, 7, 1482–1495. Google Scholar
    • 23. Yang D.; Wang J.; Wang Q.; Yuan Z.; Dai Y.; Zhou C.; Wan X.; Zhang Q.; Yang Y.Electrocatalytic CO2 Reduction over Atomically Precise Metal Nanoclusters Protected by Organic Ligands.ACS Nano2022, 16, 15681–15704. Crossref, Google Scholar
    • 24. Cai X.; Li G.; Hu W.; Zhu Y.Catalytic Conversion of CO2 over Atomically Precise Gold-Based Cluster Catalysts.ACS Catal.2022, 12, 10638–10653. Crossref, Google Scholar
    • 25. Bodiuzzaman M.; Murugesan K.; Yuan P.; Maity B.; Sagadevan A.; Malenahalli H. N.; Wang S.; Maity P.; Alotaibi M. F.; Jiang D.-E.; Abulikemu M.; Mohammed O. F.; Cavallo L.; Rueping M.; Bakr O. M.Modulating Decarboxylative Oxidation Photocatalysis by Ligand Engineering of Atomically Precise Copper Nanoclusters.J. Am. Chem. Soc.2024, 146, 26994–27005. Google Scholar
    • 26. Wang W.; Chen D.; Fung V.; Zhuang S.; Zhou Y.; Wang C.; Bian G.; Zhao Y.; Xia N.; Li J.; Deng H.; Liao L.; Yang J.; Jiang D.-E.; Wu Z.Gapped and Rotated Grain Boundary Revealed in Ultra-Small Au Nanoparticles for Enhancing Electrochemical CO2 Reduction.Angew. Chem. Int. Ed.2025, 64, e202410109. Google Scholar
    • 27. Luo G.-G.; Pan Z.-H.; Han B.-L.; Dong G.-L.; Deng C.-L.; Azam M.; Tao Y.-W.; He J.; Sun C.-F.; Sun D.Total Structure, Electronic Structure and Catalytic Hydrogenation Activity of Metal-Deficient Chiral Polyhydride Cu57 Nanoclusters.Angew. Chem. Int. Ed.2023, 62, e202306849. Google Scholar
    • 28. Albright E. L.; Levchenko T. I.; Kulkarni V. K.; Sullivan A. I.; DeJesus J. F.; Malola S.; Takano S.; Nambo M.; Stamplecoskie K.; Häkkinen H.; Tsukuda T.; Crudden C. M.N-Heterocyclic Carbene-Stabilized Atomically Precise Metal Nanoclusters.J. Am. Chem. Soc.2024, 146, 5759–5780. Google Scholar
    • 29. Wang J.; Cai J.; Ren K.-X.; Liu L.; Zheng S.-J.; Wang Z.-Y.; Zang S.-Q.Stepwise Structural Evolution Toward Robust Carboranealkynyl-Protected Copper Nanocluster Catalysts for Nitrate Electroreduction.Sci. Adv.2024, 10, eadn7556. Google Scholar
    • 30. Hu F.; Luyang H.-W.; He R.-L.; Guan Z.-J.; Yuan S.-F.; Wang Q.-M.Face-Centered Cubic Silver Nanoclusters Consolidated with Tetradentate Formamidinate Ligands.J. Am. Chem. Soc.2022, 144, 19365–19371. Google Scholar
    • 31. Hu F.; Li J.-J.; Guan Z.-J.; Yuan S.-F.; Wang Q.-M.Formation of an Alkynyl-Protected Ag112 Silver Nanocluster as Promoted by Chloride Released In Situ from CH2Cl2.Angew. Chem. Int. Ed.2020, 59, 5312–5315. Google Scholar
    • 32. Liu C.-Y.; Yuan S.-F.; Wang S.; Guan Z.-J.; Jiang D.-E.; Wang Q.-M.Structural Transformation and Catalytic Hydrogenation Activity of Amidinate-Protected Copper Hydride Clusters.Nat. Commun.2022, 13, 2082. Google Scholar
    • 33. Liu C.-Y.; Liu T.-Y.; Guan Z.-J.; Wang S.; Dong Y.-Y.; Hu F.; Jiang D.-E.; Wang Q.-M.Dramatic Difference Between Cu20H8 and Cu20H9 Clusters in Catalysis.CCS Chem.2024, 6, 1581–1590. Link, Google Scholar
    • 34. Jia J.; Wang Z.; Liu Y.; Li F.; Shang Y.; Liu Y.; Cai Q.; Zhao J.A Metallic Cu2N Monolayer with Planar Tetracoordinated Nitrogen as a Promising Catalyst for CO2 Electroreduction.J. Mater. Chem. A2022, 10, 1560–1568. Google Scholar
    • 35. Pan F.; Fang L.; Li B.; Yang X.; O’Carroll T.; Li H.; Li T.; Wang G.; Chen K.-J.; Wu G.N and OH-Immobilized Cu3 Clusters in Situ Reconstructed from Single-Metal Sites for Efficient CO2 Electromethanation in Bicontinuous Mesochannels.J. Am. Chem. Soc.2024, 146, 1423–1434. Google Scholar
    • 36. Qu M.; Zhang F.-Q.; Wang D.-H.; Li H.; Hou J.-J.; Zhang X.-M.Observation of Non-FCC Copper in Alkynyl-Protected Cu53 Nanoclusters.Angew. Chem. Int. Ed.2020, 59, 6507–6512. Google Scholar
    • 37. Dubot P.; Jousset D.; Pinet V.; Pellerin F.; Langeron J. P.Simulation of the LMM Auger Spectra of Copper.Surf. Interface Anal.1988, 12, 99–104. Google Scholar
    • 38. Yuan S.-F.; He R.-L.; Han X.-S.; Wang J.-Q.; Guan Z.-J.; Wang Q.-M.Robust Gold Nanocluster Protected with Amidinates for Electrocatalytic CO2 Reduction.Angew. Chem. Int. Ed.2021, 60, 14345–14349. Google Scholar
    • 39. Yuan S.-F.; Xu C.-Q.; Liu W.-D.; Zhang J.-X.; Li J.; Wang Q.-M.Rod-Shaped Silver Supercluster Unveiling Strong Electron Coupling Between Substituent Icosahedral Units.J. Am. Chem. Soc.2021, 143, 12261–12267. Google Scholar
    • 40. Yuan S.-F.; Guan Z.-J.; Liu W.-D.; Wang Q.-M.Solvent-Triggered Reversible Interconversion of All-Nitrogen-Donor-Protected Silver Nanoclusters and Their Responsive Optical Properties.Nat. Commun.2019, 10, 4032. Google Scholar
    • 41. Lu T.A Comprehensive Electron Wavefunction Analysis Toolbox for Chemists, Multiwfn.J. Chem. Phys.2024, 161, 082503. Google Scholar
    • 42. Lu T.; Chen F.Multiwfn: A Multifunctional Wavefunction Analyzer.J. Comput. Chem.2012, 33, 580–592. Google Scholar
    • 43. Ma F.; Zhang P.; Zheng X.; Chen L.; Li Y.; Zhuang Z.; Fan Y.; Jiang P.; Zhao H.; Zhang J.; Dong Y.; Zhu Y.; Wang D.; Wang Y.Steering the Site Distance of Atomic Cu–Cu Pairs by First-Shell Halogen Coordination Boosts CO2-to-C2 Selectivity.Angew. Chem. Int. Ed.2024, 63, e202412785. Google Scholar
    Previous article
    Next article