Nitrogen reduction reaction on small iron clusters supported by N-doped graphene: A theoretical study of the atomically precise active-site mechanism


Nonprecious metal catalysts are known of significance for electrochemical N2 reduction reaction (NRR) of which the mechanism has been illustrated by ongoing investigations of single atom catalysis. However, it remains challenging to fully understand the size-dependent synergistic effect of active sites inherited in substantial nanocatalysts. In this work, four types of small iron clusters Fen (n = 1–4) supported on nitrogen-doped graphene sheets are constructed to figure out the size dependence and synergistic effect of active sites for NRR catalytic activities. It is revealed that Fe3 and Fe4 clusters on N4G supports exhibit higher NRR activity than single-iron atom and iron dimer clusters, showing lowered limiting potential and restricted hydrogen evolution reaction (HER) which is a competitive reaction channel. In particular, the Fe4-N4G displays outstanding NRR performance for “side-on” adsorption of N2 with a small limiting potential (−0.45 V). Besides the specific structure and strong interface interaction within the Fe4-N4G itself, the high NRR activity is associated with the unique bonding/antibonding orbital interactions of N-N and N-Fe for the adsorptive N2 and NNH intermediates, as well as relatively large charge transfer between N2 and the cluster Fe4-N4G.

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  1. [1]

    Guo, C. X.; Ran, J. R.; Vasileff, A.; Qiao, S. Z. Rational design of electrocatalysts and photo(electro)catalysts for nitrogen reduction to ammonia (NH3) under ambient conditions. Energy Environ. Sci.2018, 11, 45–56.

    CAS  Google Scholar 

  2. [2]

    Ashida, Y.; Arashiba, K.; Nakajima, K.; Nishibayashi, Y. Molybdenum-catalysed ammonia production with samarium diiodide and alcohols or water. Nature2019, 568, 536–540.

    CAS  Google Scholar 

  3. [3]

    Nagaoka, K.; Eboshi, T.; Takeishi, Y.; Tasaki, R.; Honda, K.; Imamura, K.; Sato, K. Carbon-free H2 production from ammonia triggered at room temperature with an acidic RuO2/γ-Al2O3 catalyst. Sci. Adv.2017, 3, e1602747.

  4. [4]

    Wang, L.; Xia, M. K.; Wang, H.; Huang, K. F.; Qian, C. X.; Maravelias, C. T.; Ozin, G. A. Greening ammonia toward the solar ammonia refinery. Joule2018, 2, 1055–1074.

    CAS  Google Scholar 

  5. [5]

    Bhutto, S. M.; Holland, P. L. Dinitrogen activation and functionalization using β-diketiminate iron complexes. Eur. J. Inorg. Chem.2019, 2019, 1861–1869.

    CAS  Google Scholar 

  6. [6]

    Gong, Y. T.; Wu, J. Z.; Kitano, M.; Wang, J. J.; Ye, T. N.; Li, J.; Kobayashi, Y.; Kishida, K.; Abe, H.; Niwa, Y. et al. Ternary intermetallic LaCoSi as a catalyst for N2 activation. Nat. Catal.2018, 1, 178–185.

    CAS  Google Scholar 

  7. [7]

    Kobayashi, Y.; Tang, Y.; Kageyama, T.; Yamashita, H.; Masuda, N.; Hosokawa, S.; Kageyama, H. Titanium-based hydrides as heterogeneous catalysts for ammonia synthesis. J. Am. Chem. Soc.2017, 139, 18240–18246.

    CAS  Google Scholar 

  8. [8]

    Jia, H. L.; Du, A. X.; Zhang, H.; Yang, J. H.; Jiang, R. B.; Wang, J. F.; Zhang, C. Y. Site-selective growth of crystalline ceria with oxygen vacancies on gold nanocrystals for near-infrared nitrogen photofixation. J. Am. Chem. Soc.2019, 141, 5083–5086.

    CAS  Google Scholar 

  9. [9]

    Shi, M. M.; Bao, D.; Wulan, B. R.; Li, Y. H.; Zhang, Y. F.; Yan, J. M.; Jiang, Q. Au sub-nanoclusters on TiO2 toward highly efficient and selective electrocatalyst for N2 conversion to NH3 at ambient conditions. Adv. Mater.2017, 29, 1606550.

    Google Scholar 

  10. [10]

    Cui, X. Y.; Tang, C.; Zhang, Q. A review of electrocatalytic reduction of dinitrogen to ammonia under ambient conditions. Adv. Energy Mater.2018, 8, 1800369.

    Google Scholar 

  11. [11]

    Xue, X. L.; Chen, R. P.; Yan, C. Z.; Zhao, P. Y.; Hu, Y.; Zhang, W. J.; Yang, S. Y.; Jin, Z. Review on photocatalytic and electrocatalytic artificial nitrogen fixation for ammonia synthesis at mild conditions: Advances, challenges and perspectives. Nano Res.2019, 12, 1229–1249.

    CAS  Google Scholar 

  12. [12]

    Wang, F.; Ma, J. Z.; He, G. Z.; Chen, M.; Zhang, C. B.; He, H. Nanosize effect of Al2O3 in Ag/Al2O3 catalyst for the selective catalytic oxidation of ammonia. ACS Catal.2018, 8, 2670–2682.

    CAS  Google Scholar 

  13. [13]

    Tsuji, Y.; Ogasawara, K.; Kitano, M.; Kishida, K.; Abe, H.; Niwa, Y.; Yokoyama, T.; Hara, M.; Hosono, H. Control of nitrogen activation ability by Co-Mo bimetallic nanoparticle catalysts prepared via sodium naphthalenide-reduction. J. Catal.2018, 364, 31–39.

    CAS  Google Scholar 

  14. [14]

    Wang, A. Q.; Li, J.; Zhang, T. Heterogeneous single-atom catalysis. Nat. Rev. Chem.2018, 2, 65–81.

    CAS  Google Scholar 

  15. [15]

    Zheng, S. S.; Li, S. N.; Mei, Z. W.; Hu, Z. X.; Chu, M. H.; Liu, J. H.; Chen, X.; Pan, F. Electrochemical nitrogen reduction reaction performance of single-boron catalysts tuned by MXene substrates. J. Phys. Chem. Lett.2019, 10, 6984–6989.

    CAS  Google Scholar 

  16. [16]

    Zang, W. J.; Yang, T.; Zou, H. Y.; Xi, S. B.; Zhang, H.; Liu, X. M.; Kou, Z. K.; Du, Y. H.; Feng, Y. P.; Shen, L. et al. Copper single atoms anchored in porous nitrogen-doped carbon as efficient pH-universal catalysts for the nitrogen reduction reaction. ACS Catal.2019, 9, 10166–10173.

    CAS  Google Scholar 

  17. [17]

    He, C.; Wu, Z. Y.; Zhao, L.; Ming, M.; Zhang, Y.; Yi, Y. P.; Hu, J. S. Identification of FeN4 as an efficient active site for electrochemical N2 reduction. ACS Catal.2019, 9, 7311–7317.

    CAS  Google Scholar 

  18. [18]

    Li, X. F.; Li, Q. K.; Cheng, J.; Liu, L. L.; Yan, Q.; Wu, Y. C.; Zhang, X. H.; Wang, Z. Y.; Qiu, Q.; Luo, Y. Conversion of dinitrogen to ammonia by FeN3-embedded graphene. J. Am. Chem. Soc.2016, 138, 8706–8709.

    CAS  Google Scholar 

  19. [19]

    Wang, Y.; Cui, X. Q.; Zhao, J. X.; Jia, G. R.; Gu, L.; Zhang, Q. H.; Meng, L. K.; Shi, Z.; Zheng, L. R.; Wang, C. Y. et al. Rational design of Fe-N/C hybrid for enhanced nitrogen reduction electrocatalysis under ambient conditions in aqueous solution. ACS Catal.2019, 9, 336–344.

    CAS  Google Scholar 

  20. [20]

    Lü, F.; Zhao, S. Z.; Guo, R. J.; He, J.; Peng, X. Y.; Bao, H. H.; Fu, J. T.; Han, L. L.; Qi, G. C.; Luo, J. et al. Nitrogen-coordinated single Fe sites for efficient electrocatalytic N2 fixation in neutral media. Nano Energy2019, 61, 420–427.

    Google Scholar 

  21. [21]

    Guo, X. Y.; Huang, S. P. Tunin g nitrogen reduction reaction activity via controllable Fe magnetic moment: A computational study of single Fe atom supported on defective graphene. Electrochim. Acta2018, 284, 392–399.

    CAS  Google Scholar 

  22. [22]

    Wei, Z. X.; Zhang, Y. F.; Wang, S. Y.; Wang, C. Y.; Ma, J. M. Fe-doped phosphorene for the nitrogen reduction reaction. J. Mater. Chem. A2018, 6, 13790–13796.

    CAS  Google Scholar 

  23. [23]

    Choi, C.; Back, S.; Kim, N. Y.; Lim, J.; Kim, Y. H.; Jung, Y. Suppression of hydrogen evolution reaction in electrochemical N2 reduction using single-atom catalysts: A computational guideline. ACS Catal.2018, 8, 7517–7525.

    CAS  Google Scholar 

  24. [24]

    Georgakilas, V.; Tiwari, J. N.; Kemp, K. C.; Perman, J. A.; Bourlinos, A. B.; Kim, K. S.; Zboril, R. Noncovalent functionalization of graphene and graphene oxide for energy materials, biosensing, catalytic, and biomedical applications. Chem. Rev.2016, 116, 5464–5519.

    CAS  Google Scholar 

  25. [25]

    Tyo, E. C.; Vajda, S. Catalysis by clusters with precise numbers of atoms. Nat. Nanotechnol.2015, 10, 577–588.

    CAS  Google Scholar 

  26. [26]

    Cui, C. N.; Luo, Z. X.; Yao, J. N. Enhanced catalysis of Pt3 clusters supported on graphene for N-H bond dissociation. CCS Chem.2019, 1, 215–225.

    CAS  Google Scholar 

  27. [27]

    An, J. H.; Wang, Y. H.; Lu, J. M.; Zhang, J.; Zhang, Z. X.; Xu, S. T.; Liu, X. Y.; Zhang, T.; Gocyla, M.; Heggen, M. et al. Acid-promoter-free ethylene methoxycarbonylation over Ru-clusters/ceria: The catalysis of interfacial lewis acid-base pair. J. Am. Chem. Soc.2018, 140, 4172–4181.

    CAS  Google Scholar 

  28. [28]

    Ren, Y.; Yang, Y.; Zhao, Y. X.; He, S. G. Size-dependent reactivity of rhodium cluster anions toward methane. J. Phys. Chem. C2019, 123, 17035–17042.

    CAS  Google Scholar 

  29. [29]

    Yang, B.; Liu, C.; Halder, A.; Tyo, E. C.; Martinson, A. B. F.; Seifer, S.; Zapol, P.; Curtiss, L. A.; Vajda, S. Copper cluster size effect in methanol synthesis from CO2. J. Phys. Chem. C2017, 121, 10406–10412.

    CAS  Google Scholar 

  30. [30]

    Kong, J. M.; Lim, A.; Yoon, C.; Jang, J. H.; Ham, H. C.; Han, J.; Nam, S.; Kim, D.; Sung, Y. E.; Choi, J. et al. Electrochemical synthesis of NH3 at low temperature and atmospheric pressure using a γ-Fe2O3 catalyst. ACS Sustainable Chem. Eng.2017, 5, 10986–10995.

    CAS  Google Scholar 

  31. [31]

    Manjunatha, R.; Karajić, A.; Goldstein, V.; Schechter, A. Electrochemical ammonia generation directly from nitrogen and air using an iron-oxide/titania-based catalyst at ambient conditions. ACS Appl. Mater. Interfaces2019, 11, 7981–7989.

    CAS  Google Scholar 

  32. [32]

    Xia, L.; Li, B. H.; Zhang, Y.; Zhang, R.; Ji, L.; Chen, H. Y.; Cui, G. W.; Zheng, H. G.; Sun, X. P.; Xie, F. Y. et al. Cr2O3 nanoparticle-reduced graphene oxide hybrid: A highly active electrocatalyst for N2 reduction at ambient conditions. Inorg. Chem.2019, 58, 2257–2260.

    CAS  Google Scholar 

  33. [33]

    Chen, G. F.; Ren, S. Y.; Zhang, L. L.; Cheng, H.; Luo, Y. R.; Zhu, K. H.; Ding, L. X.; Wang, H. H. Advances in electrocatalytic N2 reduction-strategies to tackle the selectivity challenge. Small Methods2019, 3, 1800337.

    Google Scholar 

  34. [34]

    Li, S. J.; Bao, D.; Shi, M. M.; Wulan, B. R.; Yan, J. M.; Jiang, Q. Amorphizing of Au nanoparticles by CeOx-RGO hybrid support towards highly efficient electrocatalyst for N2 reduction under ambient conditions}. Adv. Mater.2017, 29, 1700001.

    Google Scholar 

  35. [35]

    Nazemi, M.; El-Sayed, M. A. Electrochemical synthesis of ammonia from N2 and H2O under ambient conditions using pore-size-controlled hollow gold nanocatalysts with tunable plasmonic properties. J. Phys. Chem. Lett.2018, 9, 5160–5166.

    CAS  Google Scholar 

  36. [36]

    Chen, S. M.; Perathoner, S.; Ampelli, C.; Mebrahtu, C.; Su, D. S.; Centi, G. Electrocatalytic synthesis of ammonia at room temperature and atmospheric pressure from water and nitrogen on a carbon-nanotube-based electrocatalyst. Angew. Chem., Int. Ed.2017, 56, 2699–2703.

    CAS  Google Scholar 

  37. [37]

    Yao, Y.; Zhu, S. Q.; Wang, H. J.; Li, H.; Shao, M. H. A spectroscopic study on the nitrogen electrochemical reduction reaction on gold and platinum surfaces. J. Am. Chem. Soc.2018, 140, 1496–1501.

    CAS  Google Scholar 

  38. [38]

    Zhao, S. L.; Lu, X. Y.; Wang, L. Z.; Gale, J.; Amal, R. Carbon-based metal-free catalysts for electrocatalytic reduction of nitrogen for synthesis of ammonia at ambient conditions. Adv. Mater.2019, 31, 1805367.

    Google Scholar 

  39. [39]

    Tanaka, H.; Nishibayashi, Y.; Yoshizawa, K. Interplay between theory and experiment for ammonia synthesis catalyzed by transition metal complexes. Acc. Chem. Res.2016, 49, 987–995.

    CAS  Google Scholar 

  40. [40]

    Licht, S.; Cui, B. C.; Wang, B. H.; Li, F. F.; Lau, J.; Liu, S. Z. Ammonia synthesis by N2 and steam electrolysis in molten hydroxide suspensions of nanoscale Fe2O3. Science2014, 345, 637–640.

    CAS  Google Scholar 

  41. [41]

    Kosaka, F.; Nakamura, T.; Oikawa, A.; Otomo, J. Electrochemical acceleration of ammonia synthesis on Fe-based alkali-promoted electrocatalyst with proton conducting solid electrolyte. ACS Sustainable Chem. Eng.2017, 5, 10439–10446.

    CAS  Google Scholar 

  42. [42]

    Hu, L.; Khaniya, A.; Wang, J.; Chen, G.; Kaden, W. E.; Feng, X. F. Ambient electrochemical ammonia synthesis with high selectivity on Fe/Fe oxide catalyst. ACS Catal.2018, 8, 9312–9319.

    CAS  Google Scholar 

  43. [43]

    Qian, J.; An, Q.; Fortunelli, A.; Nielsen, R. J.; Goddard III, W. A. Reaction mechanism and kinetics for ammonia synthesis on the Fe(111) surface. J. Am. Chem. Soc.2018, 140, 6288–6297.

    CAS  Google Scholar 

  44. [44]

    Li, C.; Fu, Y. S.; Wu, Z.; Xia, J. W.; Wang, X. Sandwich-like reduced graphene oxide/yolk-shell-structured Fe@Fe3O4/carbonized paper as an efficient freestanding electrode for electrochemical synthesis of ammonia directly from H2O and nitrogen. Nanoscale2019, 11, 12997–13006.

    CAS  Google Scholar 

  45. [45]

    Maheshwari, S.; Rostamikia, G.; Janik, M. J. Elementary kinetics of nitrogen electroreduction on Fe surfaces. J. Chem. Phys.2019, 150, 041708.

    Google Scholar 

  46. [46]

    Mou, X. L.; Zhang, B. S.; Li, Y.; Yao, L. D.; Wei, X. J.; Su, D. S.; Shen, W. J. Rod-shaped Fe2O3 as an efficient catalyst for the selective reduction of nitrogen oxide by ammonia. Angew. Chem., Int. Ed.2012, 51, 2989–2993.

    CAS  Google Scholar 

  47. [47]

    Zhang, L. F.; Zhao, W. H.; Zhang, W. H.; Chen, J.; Hu, Z. P. gt-C3N4 coordinated single atom as an efficient electrocatalyst for nitrogen reduction reaction. Nano Res.2019, 12, 1181–1186.

    CAS  Google Scholar 

  48. [48]

    Yang, L. M.; Yi, G. P.; Hou, Y. N.; Cheng, H. Y.; Luo, X. B.; Pavlostathis, S. G.; Luo, S. L.; Wang, A. J. Building electrode with three-dimensional macroporous interface from biocompatible polypyrrole and conductive graphene nanosheets to achieve highly efficient microbial electrocatalysis. Biosens. Bioelectron.2019, 141, 111444.

    CAS  Google Scholar 

  49. [49]

    Luo, Z. X.; Castleman, A. W. Jr.; Khanna, S. N. Reactivity of metal clusters. Chem. Rev.2016, 116, 14456–14492.

    CAS  Google Scholar 

  50. [50]

    Luo, Z. X.; Castleman, A. W. Special and general superatoms. Acc. Chem. Res.2014, 47, 2931–2940.

    CAS  Google Scholar 

  51. [51]

    Kresse, G.; Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B1996, 54, 11169–11186.

    CAS  Google Scholar 

  52. [52]

    Wang, R. B.; Hellman, A. Hybrid functional study of the electro-oxidation of water on pristine and defective hematite (0001). J. Phys. Chem. C2019, 123, 2820–2827.

    CAS  Google Scholar 

  53. [53]

    Rohling, R. Y.; Tranca, I. C.; Hensen, E. J. M.; Pidko, E. A. Correlations between density-based bond orders and orbital-based bond energies for chemical bonding analysis. J. Phys. Chem. C2019, 123, 2843–2854.

    CAS  Google Scholar 

  54. [54]

    Maintz, S.; Deringer, V. L.; Tchougreeff, A. L.; Dronskowski, R. LOBSTER: A tool to extract chemical bonding from plane-wave based DFT. J. Comput. Chem.2016, 37, 1030–1035.

    CAS  Google Scholar 

  55. [55]

    Maintz, S.; Deringer, V. L.; Tchougréeff, A. L.; Dronskowski, R. Analytic projection from plane-wave and PAW wavefunctions and application to chemical-bonding analysis in solids. J. Comput. Chem.2013, 34, 2557–2567.

    CAS  Google Scholar 

  56. [56]

    Malko, D.; Kucernak, A.; Lopes, T. In situ electrochemical quantification of active sites in Fe-N/C non-precious metal catalysts. Nat. Commun.2016, 7, 13285.

    CAS  Google Scholar 

  57. [57]

    Nørskov, J. K.; Rossmeisl, J.; Logadottir, A.; Lindqvist, L.; Kitchin, J. R.; Bligaard, T.; Jónsson, H. Origin of the overpotential for oxygen reduction at a fuel-cell cathode. J. Phys. Chem. B2004, 108, 17886–17892.

    Google Scholar 

  58. [58]

    Cui, C. N.; Han, J. Y.; Zhu, X. L.; Liu, X.; Wang, H.; Mei, D. H.; Ge, Q. F. Promotional effect of surface hydroxyls on electrochemical reduction of CO2 over SnOx/Sn electrode. J. Catal.2016, 343, 257–265.

    CAS  Google Scholar 

  59. [59]

    Psofogiannakis, G.; St-Amant, A.; Ternan, M. Methane oxidation mechanism on Pt(111): A cluster model DFT study. J. Phys. Chem. B2006, 110, 24593–24605.

    CAS  Google Scholar 

  60. [60]

    Montoya, J. H.; Tsai, C.; Vojvodic, A.; Nørskov, J. K. The challenge of electrochemical ammonia synthesis: A new perspective on the role of nitrogen scaling relations. ChemSusChem2015, 8, 2180–2186.

    CAS  Google Scholar 

  61. [61]

    Liu, J. C.; Ma, X. L.; Li, Y.; Wang, Y. G.; Xiao, H.; Li, J. Heterogeneous Fe3 single-cluster catalyst for ammonia synthesis via an associative mechanism. Nat. Commun.2018, 9, 1610.

    Google Scholar 

  62. [62]

    McWilliams, S. F.; Holland, P. L. Dinitrogen binding and cleavage by multinuclear iron complexes. Acc. Chem. Res.2015, 48, 2059–2065.

    CAS  Google Scholar 

  63. [63]

    Hoffman, B. M.; Lukoyanov, D.; Yang, Z. Y.; Dean, D. R.; Seefeldt, L. C. Mechanism of nitrogen fixation by nitrogenase: The next stage. Chem. Rev.2014, 114, 4041–4062.

    CAS  Google Scholar 

  64. [64]

    Liu, C. W.; Li, Q. Y.; Wu, C. Z.; Zhang, J.; Jin, Y. G.; MacFarlane, D. R.; Sun, C. H. Single-boron catalysts for nitrogen reduction reaction. J. Am. Chem. Soc.2019, 141, 2884–2888.

    CAS  Google Scholar 

  65. [65]

    Lu, Z. Y.; Chen, G. X.; Siahrostami, S.; Chen, Z. H.; Liu, K.; Xie, J.; Liao, L.; Wu, T.; Lin, D. C.; Liu, Y. Y. et al. High-efficiency oxygen reduction to hydrogen peroxide catalysed by oxidized carbon materials. Nat. Catal.2018, 1, 156–162.

    CAS  Google Scholar 

  66. [66]

    Liu, H. N.; Li, W.; Liu, F.; Pei, Z. Z.; Shi, J.; Wang, Z. J.; He, D. H.; Chen, Y. Homogeneous, heterogeneous, and biological catalysts for electrochemical N2 reduction toward NH3 under ambient conditions. ACS Catal.2019, 9, 5245–5267.

    CAS  Google Scholar 

  67. [67]

    Van Der Ham, C. J. M.; Koper, M. T.; Hetterscheid, D. G. H. Challenges in reduction of dinitrogen by proton and electron transfer. Chem. Soc. Rev.2014, 43, 5183–5191.

    CAS  Google Scholar 

  68. [68]

    Skúlason, E.; Bligaard, T.; Gudmundsdóttir, S.; Studt, F.; Rossmeisl, J.; Abild-Pedersen, F.; Vegge, T.; Jónsson, H.; Nørskov, J. K. A theoretical evaluation of possible transition metal electro-catalysts for N2 reduction. Phys. Chem. Chem. Phys.2012, 14, 1235–1245.

    Google Scholar 

  69. [69]

    Wang, H. W.; Gu, X. K.; Zheng, X. S.; Pan, H. B.; Zhu, J. F.; Chen, S.; Cao, L. N.; Li, W. X.; Lu, J. L. Disentangling the size-dependent geometric and electronic effects of palladium nanocatalysts beyond selectivity. Sci. Adv.2019, 5, eaat6413.

    Google Scholar 

  70. [70]

    Ma, X. L.; Liu, J. C.; Xiao, H.; Li, J. Surface single-cluster catalyst for N2-to-NH3 thermal conversion. J. Am. Chem. Soc.2018, 140, 46–49.

    CAS  Google Scholar 

  71. [71]

    Ling, C. Y.; Bai, X. W.; Ouyang, Y. X.; Du, A. J.; Wang, J. L. Single molybdenum atom anchored on N-doped carbon as a promising electrocatalyst for nitrogen reduction into ammonia at ambient conditions. J. Phys. Chem. C2018, 122, 16842–16847.

    CAS  Google Scholar 

  72. [72]

    Deringer, V. L.; Tchougreeff, A. L.; Dronskowski, R. Crystal orbital Hamilton population (COHP) analysis as projected from plane-wave basis sets. J. Phys. Chem. A2011, 115, 5461–5466.

    CAS  Google Scholar 

  73. [73]

    Dronskowski, R.; Bloechl, P. E. Crystal orbital Hamilton populations (COHP): Energy-resolved visualization of chemical bonding in solids based on density-functional calculations. J. Phys. Chem.1993, 97, 8617–8624.

    CAS  Google Scholar 

  74. [74]

    Hao, Y. C.; Guo, Y.; Chen, L. W.; Shu, M.; Wang, X. Y.; Bu, T. A.; Gao, W. Y.; Zhang, N.; Su, X.; Feng, X. et al. Promoting nitrogen electro-reduction to ammonia with bismuth nanocrystals and potassium cations in water. Nat. Catal.2019, 2, 448–456.

    CAS  Google Scholar 

  75. [75]

    Bickelhaupt, F. M.; Nagle, J. K.; Klemm, W. L. Role of s-p orbital mixing in the bonding and properties of second-period diatomic molecules. J. Phys. Chem. A2008, 112, 2437–2446.

    CAS  Google Scholar 

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This work was financially supported by the National Natural Science Foundation of China (Nos. 21802146 and 21722308), CAS Key Research Project of Frontier Science (No. QYZDB-SSW-SLH024), and Frontier Cross Project of National Laboratory for Molecular Sciences (No. 051Z011BZ3).

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Cui, C., Zhang, H. & Luo, Z. Nitrogen reduction reaction on small iron clusters supported by N-doped graphene: A theoretical study of the atomically precise active-site mechanism. Nano Res. 13, 2280–2288 (2020).

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  • N2 reduction reaction (NRR)
  • iron clusters
  • cluster catalysis
  • active-site mechanism
  • density functional theory (DFT)