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Iridium single-atom catalyst on nitrogen-doped carbon for formic acid oxidation synthesized using a general host–guest strategy


Single-atom catalysts not only maximize metal atom efficiency, they also display properties that are considerably different to their more conventional nanoparticle equivalents, making them a promising family of materials to investigate. Herein we developed a general host–guest strategy to fabricate various metal single-atom catalysts on nitrogen-doped carbon (M1/CN, M = Pt, Ir, Pd, Ru, Mo, Ga, Cu, Ni, Mn). The iridium variant Ir1/CN electrocatalyses the formic acid oxidation reaction with a mass activity of 12.9 \({{{\rm{A}}\,{\rm{mg}}^{-1}_{{\rm{Ir}}}}}\) whereas an Ir/C nanoparticle catalyst is almost inert (~4.8 × 10−3\({{{\rm{A}}\,{\rm{mg}}^{-1}_{{\rm{Ir}}}}}\)). The activity of Ir1/CN is also 16 and 19 times greater than those of Pd/C and Pt/C, respectively. Furthermore, Ir1/CN displays high tolerance to CO poisoning. First-principle density functional theory reveals that the properties of Ir1/CN stem from the spatial isolation of iridium sites and from the modified electronic structure of iridium with respect to a conventional nanoparticle catalyst.

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Fig. 1: Synthesis and structural characterizations of Ir1/CN.
Fig. 2: Characterization of atomically dispersed M1/CN (M = Pt, Pd, Ru, Mo, Ga, Cu, Ni, Mn).
Fig. 3: Electrocatalytic activity of M1/CN for the FAOR.
Fig. 4: Electrocatalytic activity of Ir1/CN, iridium nanoparticles on carbon (Ir/C) and commercial nanocatalysts.
Fig. 5: Electrocatalytic stability of Ir1/CN and its tolerance to CO poisoning compared with commercial nanocatalysts.
Fig. 6: Catalytic mechanism study of Ir1/CN and Ir/C for the FAOR.

Data availability

Full data supporting the findings of this study are available within the article and its Supplementary Information, as well as from the corresponding author on reasonable request.


  1. 1.

    Thomas, J. M. Catalysis: tens of thousands of atoms replaced by one. Nature 525, 325–326 (2015).

    CAS  PubMed  Google Scholar 

  2. 2.

    Qiao, B. et al. Single-atom catalysis of CO oxidation using Pt1/FeOx. Nat. Chem. 3, 634–641 (2011).

    CAS  PubMed  Google Scholar 

  3. 3.

    Yang, X. F. et al. Single-atom catalysts: a new frontier in heterogeneous catalysis. Acc. Chem. Res. 46, 1740–1748 (2013).

    CAS  PubMed  Google Scholar 

  4. 4.

    Yin, P. et al. Single cobalt atoms with precise N-coordination as superior oxygen reduction reaction catalysts. Angew. Chem. Int. Ed. 55, 10800–10805 (2016).

    CAS  Google Scholar 

  5. 5.

    Wei, S. et al. Direct observation of noble metal nanoparticles transforming to thermally stable single atoms. Nat. Nanotechnol. 13, 856–861 (2018).

    CAS  PubMed  Google Scholar 

  6. 6.

    Wang, L. et al. Atomic-level insights in optimizing reaction paths for hydroformylation reaction over Rh/CoO single-atom catalyst. Nat. Commun. 7, 14036 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  7. 7.

    Malta, G. et al. Identification of single-site gold catalysis in acetylene hydrochlorination. Science 355, 1399–1403 (2017).

    CAS  PubMed  Google Scholar 

  8. 8.

    Zhang, J. et al. Cation vacancy stabilization of single-atomic-site Pt1/Ni(OH)x catalyst for diboration of alkynes and alkenes. Nat. Commun. 9, 1002 (2018).

    PubMed  PubMed Central  Google Scholar 

  9. 9.

    Jones, J. et al. Thermally stable single-atom platinum-on-ceria catalysts via atom trapping. Science 353, 150–154 (2016).

    CAS  PubMed  Google Scholar 

  10. 10.

    Yang, S., Kim, J., Tak, Y. J., Soon, A. & Lee, H. Single-atom catalyst of platinum supported on titanium nitride for selective electrochemical reactions. Angew. Chem. Int. Ed. 55, 2058–2062 (2016).

    CAS  Google Scholar 

  11. 11.

    Cheng, N. et al. Platinum single-atom and cluster catalysis of the hydrogen evolution reaction. Nat. Commun. 7, 13638 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  12. 12.

    Zhang, J. et al. Single platinum atoms immobilized on an MXene as an efficient catalyst for the hydrogen evolution reaction. Nat. Catal. 1, 985–992 (2018).

    CAS  Google Scholar 

  13. 13.

    Chen, Y. et al. Discovering partially charged single-atom Pt for enhanced anti-Markovnikov alkene hydrosilylation. J. Am. Chem. Soc. 140, 7407–7410 (2018).

    CAS  PubMed  Google Scholar 

  14. 14.

    Yang, H. B. et al. Atomically dispersed Ni(i) as the active site for electrochemical CO2 reduction. Nat. Energy 3, 140–147 (2018).

    CAS  Google Scholar 

  15. 15.

    Choi, C. H. et al. Tuning selectivity of electrochemical reactions by atomically dispersed platinum catalyst. Nat. Commun. 7, 10922 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  16. 16.

    Guo, X. et al. Direct, nonoxidative conversion of methane to ethylene, aromatics, and hydrogen. Science 344, 616–619 (2014).

    CAS  PubMed  Google Scholar 

  17. 17.

    Siahrostami, S. et al. Enabling direct H2O2 production through rational electrocatalyst design. Nat. Mater. 12, 1137–1143 (2013).

    CAS  PubMed  Google Scholar 

  18. 18.

    Rice, C. et al. Direct formic acid fuel cells. J. Power Sources 111, 83–89 (2002).

    CAS  Google Scholar 

  19. 19.

    Rice, C., Ha, S., Masel, R. I. & Wieckowski, A. Catalysts for direct formic acid fuel cells. J. Power Sources 115, 229–235 (2003).

    CAS  Google Scholar 

  20. 20.

    Ji, X. et al. Nanocrystalline intermetallics on mesoporous carbon for direct formic acid fuel cell anodes. Nat. Chem. 2, 286–293 (2010).

    CAS  PubMed  Google Scholar 

  21. 21.

    Tian, N., Zhou, Z.-Y., Sun, S.-G., Ding, Y. & Wang, Z. L. Synthesis of tetrahexahedral platinum nanocrystals with high-index facets and high electro-oxidation activity. Science 316, 732–735 (2007).

    CAS  PubMed  Google Scholar 

  22. 22.

    Duchesne, P. N. et al. Golden single-atomic-site platinum electrocatalysts. Nat. Mater. 17, 1033–1039 (2018).

    CAS  PubMed  Google Scholar 

  23. 23.

    Liu, J. et al. Microbial synthesis of highly dispersed PdAu alloy for enhanced electrocatalysis. Sci. Adv. 2, e1600858 (2016).

    PubMed  PubMed Central  Google Scholar 

  24. 24.

    Perales-Rondon, J. V., Ferre-Vilaplana, A., Feliu, J. M. & Herrero, E. Oxidation mechanism of formic acid on the bismuth adatom-modified Pt(111) surface. J. Am. Chem. Soc. 136, 13110–13113 (2014).

    CAS  PubMed  Google Scholar 

  25. 25.

    Xi, Z. et al. Stabilizing CuPd nanoparticles via CuPd coupling to WO2.72 nanorods in electrochemical oxidation of formic acid. J. Am. Chem. Soc. 139, 15191–15196 (2017).

    CAS  PubMed  Google Scholar 

  26. 26.

    Chang, J., Feng, L., Liu, C., Xing, W. & Hu, X. An effective Pd-Ni2P/C anode catalyst for direct formic acid fuel cells. Angew. Chem. Int. Ed. 53, 122–126 (2014).

    CAS  Google Scholar 

  27. 27.

    Rong, H. et al. Kinetically controlling surface structure to construct defect-rich intermetallic nanocrystals: effective and stable catalysts. Adv. Mater. 28, 2540–2546 (2016).

    CAS  PubMed  Google Scholar 

  28. 28.

    Niu, Z., Peng, Q., Gong, M., Rong, H. & Li, Y. Oleylamine-mediated shape evolution of palladium nanocrystals. Angew. Chem. Int. Ed. 50, 6315–6319 (2011).

    CAS  Google Scholar 

  29. 29.

    Huang, X. et al. Freestanding palladium nanosheets with plasmonic and catalytic properties. Nat. Nanotechnol. 6, 28–32 (2011).

    CAS  PubMed  Google Scholar 

  30. 30.

    Tianou, H. et al. Inflating hollow nanocrystals through a repeated kirkendall cavitation process. Nat. Commun. 8, 1261 (2017).

    PubMed  PubMed Central  Google Scholar 

  31. 31.

    Zitolo, A. et al. Identification of catalytic sites for oxygen reduction in iron- and nitrogen-doped graphene materials. Nat. Mater. 14, 937–942 (2015).

    CAS  PubMed  Google Scholar 

  32. 32.

    Jasinski, R. A new fuel cell cathode catalyst. Nature 201, 1212–1213 (1964).

    CAS  Google Scholar 

  33. 33.

    Bashyam, R. & Zelenay, P. A class of non-precious metal composite catalysts for fuel cells. Nature 443, 63–66 (2006).

    CAS  PubMed  Google Scholar 

  34. 34.

    Chen, Y. et al. Isolated single iron atoms anchored on N-doped porous carbon as an efficient electrocatalyst for the oxygen reduction reaction. Angew. Chem. Int. Ed. 56, 6937–6941 (2017).

    CAS  Google Scholar 

  35. 35.

    Wang, X., Tang, Y., Gao, Y. & Lu, T. Carbon-supported Pd–Ir catalyst as anodic catalyst in direct formic acid fuel cell. J. Power Sources 175, 784–788 (2008).

    CAS  Google Scholar 

  36. 36.

    Taylor, A. K. et al. Block copolymer templated synthesis of PtIr bimetallic nanocatalysts for the formic acid oxidation reaction. J. Mater. Chem. A 5, 21514–21527 (2017).

    CAS  Google Scholar 

  37. 37.

    Al-Akraa, I. M., Mohammad, A. M., El-Deab, M. S. & El-Anadouli, B. E. Advances in direct formic acid fuel cells: fabrication of efficient Ir/Pd nanocatalysts for formic acid electro-oxidation. Int. J. Electrochem. Sci. 10, 3282–3290 (2015).

    CAS  Google Scholar 

  38. 38.

    Hoene, J. V., Charles, R. G. & Hickam, W. M. Thermal decomposition of metal acetylacetonates: mass spectrometer studies. J. Phys. Chem. 62, 1098–1101 (2002).

    Google Scholar 

  39. 39.

    Jiang, H. L. et al. From metal–organic framework to nanoporous carbon: toward a very high surface area and hydrogen uptake. J. Am. Chem. Soc. 133, 11854–11857 (2011).

    CAS  PubMed  Google Scholar 

  40. 40.

    Proietti, E. et al. Iron-based cathode catalyst with enhanced power density in polymer electrolyte membrane fuel cells. Nat. Commun. 2, 416 (2011).

    PubMed  Google Scholar 

  41. 41.

    Zheng, Y. et al. MOF-derived nitrogen-doped nanoporous carbon for electroreduction of CO2 to CO: the calcining temperature effect and the mechanism. Nanoscale 11, 4911–4917 (2019).

    CAS  PubMed  Google Scholar 

  42. 42.

    Shimizu, K.-i. et al. Quantitative determination of average rhodium oxidation state by a simple XANES analysis. Appl. Catal. B 111, 509–514 (2012).

    Google Scholar 

  43. 43.

    Yoshida, D. H., Nonoyama, S. & Hattori, Y. Y. T. Quantitative determination of platinum oxidation state by XANES analysis. Phys. Scr. 2005, 813 (2005).

    Google Scholar 

  44. 44.

    Chen, L.-F. et al. Synthesis of nitrogen-doped porous carbon nanofibers as an efficient electrode material for supercapacitors. ACS Nano 6, 7092–7102 (2012).

    CAS  PubMed  Google Scholar 

  45. 45.

    Lovic, J. D. et al. Kinetic study of formic acid oxidation on carbon-supported platinum electrocatalyst. J. Electroanal. Chem. 581, 294–302 (2005).

    CAS  Google Scholar 

  46. 46.

    Wang, J.-Y., Zhang, H.-X., Jiang, K. & Cai, W.-B. From HCOOH to CO at Pd electrodes: a surface-enhanced infrared spectroscopy study. J. Am. Chem. Soc. 133, 14876–14879 (2011).

    CAS  PubMed  Google Scholar 

  47. 47.

    Zhou, Y. et al. Poisoning and regeneration of Pd catalyst in direct formic acid fuel cell. Electrochim. Acta 55, 5024–5027 (2010).

    CAS  Google Scholar 

  48. 48.

    Yeung, S. K. & Chan, K. S. Selective oxidation of (porphyrinato)iridium(iii) arylethyls by nitroxide: evidence for stabilization of carbon-centered Ir–CH2–CHR radicals by iridium. Organometallics 24, 6426–6430 (2005).

    CAS  Google Scholar 

  49. 49.

    Zhang, T. et al. Iridium ultrasmall nanoparticles, worm-like chain nanowires, and porous nanodendrites: one-pot solvothermal synthesis and catalytic CO oxidation activity. Surf. Sci. 648, 319–327 (2016).

    CAS  Google Scholar 

  50. 50.

    Li, D. et al. Surfactant removal for colloidal nanoparticles from solution synthesis: the effect on catalytic performance. ACS Catal. 2, 1358–1362 (2012).

    CAS  Google Scholar 

  51. 51.

    Ziaei-Azad, H. & Semagina, N. Bimetallic catalysts: requirements for stabilizing PVP removal depend on the surface composition. Appl. Catal. A 482, 327–335 (2014).

    CAS  Google Scholar 

  52. 52.

    Ravel, B. & Newville, M. ATHENA and ARTEMIS: interactive graphical data analysis using IFEFFIT. Phys. Scr. 115, 1007–1010 (2005).

    Google Scholar 

  53. 53.

    Joly, Y. X-ray absorption near-edge structure calculations beyond the muffin-tin approximation. Phys. Rev. B 63, 125120 (2001).

    Google Scholar 

  54. 54.

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

    PubMed  Google Scholar 

  55. 55.

    Kresse, G. & Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comp. Mater. Sci. 6, 15–50 (1996).

    CAS  Google Scholar 

  56. 56.

    Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996).

    CAS  Google Scholar 

  57. 57.

    Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758–1775 (1999).

    CAS  Google Scholar 

  58. 58.

    Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).

    CAS  Google Scholar 

  59. 59.

    Bader, R. F. A quantum theory of molecular structure and its applications. Chem. Rev. 91, 893–928 (1991).

    CAS  Google Scholar 

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The authors thank M.F. Li (University of California at Los Angeles) who provided insight and expertise that greatly assisted the research. This work was supported by the National Key R&D Program of China (grant no. 2018YFA0702003), the National Natural Science Foundation of China (grant nos. 21890383, 21671117, 21871159) and the Beijing Municipal Science & Technology Commission (grant no. Z191100007219003).

Author information




D.W. and Y.L. conceived the idea, designed the study, planned synthesis and wrote the paper. Z.L., Y.C. and S.J. performed most of the reactions, collected and analysed the data, and wrote the paper. L.G., Y.G. and J. Luo performed electron-microscopy characterizations. W.C., Y.W., L.Z., J.D., T.Y., W.L. and S. W. carried out the X-ray absorption fine structure characterizations. Y.T., J. Li, C.P. and P.H. finished the DFT calculations. A.L. performed the in situ ETEM characterizations. J. Zhao helped to synthesize and characterize the iridium homogeneous compound. W.Z., Z.Z. and W.X. helped with electrochemical measurements and the analysis of electrocatalytic results. W.-C.C helped with the analysis of electron-microscopy characterizations. C.-T.H., Y.X., Q.L., M.Z., Z.C., N.F., X.G., J.W. and J. Zhang performed some of the synthesis experiments. Y.W., C.C., Q.P., X.D., Y.H. and X.-M.C. provided valuable suggestions and helped revise the manuscript.

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Correspondence to Dingsheng Wang or Yadong Li.

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Li, Z., Chen, Y., Ji, S. et al. Iridium single-atom catalyst on nitrogen-doped carbon for formic acid oxidation synthesized using a general host–guest strategy. Nat. Chem. 12, 764–772 (2020).

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